WO2025172336A1

WO2025172336A1 - Breast implant

Info

Publication number: WO2025172336A1
Application number: PCT/EP2025/053674
Authority: WO
Inventors: Peter Forsell
Original assignee: Implantica Patent Ltd
Current assignee: Implantica Patent Ltd
Priority date: 2024-02-16
Filing date: 2025-02-12
Publication date: 2025-08-21
Anticipated expiration: 2026-08-16

Abstract

A breast implant system comprising a plurality of chambers including a first fluid chamber (1) and a second fluid chamber (2), said first and second fluid chambers (1, 2) being adapted for implantation in a human body with the first fluid chamber (1) forming part of a breast implant (10), said first and second fluid chambers (1, 2) being interconnected when implanted for fluid to be transferred between the first and second fluid chambers (1, 2) so as to change their respective fluid content.

Description

BREAST IMPLANT BACKGROUND OF THE INVENTION _{[001] The present invention relates to a breast implant and breast implant system which allows the shape of a breast implant to be varied} after its implantation in the patient’s body. _{[002] Breast implants are typically used to either replace a natural breast that has been removed, e.g. due to cancer, or to increase the} _{size of a natural breast when the natural size is considered unsatisfactory. In general, people who desire to change the overall size and shape} _{of their breast implants after implantation have to undergo major surgery. It would be desirable that the patient can adjust the size and/or} _{shape of the breast implant easily, depending on current needs. For instance, as time goes by, the patient might no longer be happy with the} _{size or shape of the artificial breast. Or, the patient might want to change the size or shape only temporarily. For instance, one might wish to} _{reduce the volume of the breast implant during sports activities or one might wish to enlarge the size for a particular event, such as a party} or the like. _{[003] US 6,875,233 B1 discloses a breast implant that allows the overall size and shape thereof to be changed once it has been surgically} implanted. Such breast implant includes an exterior shell and an inner bladder. The exterior shell is typically a bellows having a plurality of _{pleats, so that the outer size of the implant is variable. As the bladder is filled, the exterior shell expands in a manner that creates a lifting} effect and a ballooning effect. A valve connected to both the exterior shell and the inner bladder can be used to fill the bladder external to _{the patient, without the need for further surgery after the implant has been implanted in the patient. The bladder may be filled with a liquid,} _{a gas, or a solid, and such filler can be added and removed through the valve as needed. The valve either remains external, so that it can be} used without any further surgery, or it can be located under the patient's skin, in which case minor surgery must be performed to access the valve. However, the options for changing the shape of this prior art breast implant are limited. In addition, it is inconvenient for the patient that the valve for accessing the inner bladder of the breast implant permanently penetrates the patient's skin, or, where it is implanted subcutaneously, requires minor surgery to be accessed. _{[004] US 2003/0074084 A1 discloses a breast implant with a plurality of chambers. The chambers are differently pressurized in order} to control the shape of the breast implant upon inflation thereof. Each chamber may be provided with a pair of conduits for alternatively delivering fluid to, and removing fluid from, the chamber. Terminal connectors of such conduits can be easily located by medical practitioners for delivery of fluid to, or removal of fluid from, a desired chamber either manually or assisted by machinery. Alternatively, fluid can be supplied or removed by inserting a hollow needle directly into the chambers of the breast implants. While the options of changing the shape of this prior art breast implant are improved over the breast implant disclosed in US 6,875,233 B1, a medical practitioner is still needed to achieve different sizes and shapes of the breast implant after its implantation. _{[005] In a simpler embodiment described in WO 2009/095259 A1, one-way valves are each disposed between two adjacent chambers,} for enabling a transfer of fluid from a first to a second of the adjacent chambers, upon application of an external compressive force to the first chamber. This way, the valves enable reshaping of the breast implant merely through manipulation. It is even suggested to automatically _{open and close the valves by wireless remote control. While this embodiment would allow the shape of the breast implant to be changed non-} invasively merely through manipulation, the size of the breast, i.e., the volume of the breast implant, would not be affected thereby. _{[006] WO 2009/095259 A1 further discloses breast implant systems comprising a plurality of chambers which are interconnected when} implanted, such that fluid can be exchanged between them to change their respective fluid content. Various embodiments are disclosed for _{(a) changing the shape, but not the volume, (b) for changing the shape and also the volume without a change of the breast implant's mass} (this being achieved by causing a gas-filled chamber to be compressed when liquid is exchanged between chambers of the breast implant), _{and (c) for changing the shape and also the volume of the breast implant, which involves a change of the breast implant's mass. It is further} described that fluid exchange between the chambers can be achieved by manually compressing the one or the other fluid chamber, preferred embodiments include a fluid reservoir implanted remote from the breast implant in the patient's abdominal cavity or inside the patient's chest _{area, such as outside the thorax under the minor pectoralis muscle, or between the major and the minor pectoralis muscles. A pump may be} provided for pumping the fluid between the chambers of the breast implant and/or between one or more chambers and the remotely implanted _{reservoir. The pump may be manually driven, for which purpose it is advantageously implanted subcutaneously. Alternatively, the pump may} _{be driven by a motor, which may likewise be implanted. Pump and/or motor may be driven by energy wirelessly transmitted from outside the} patient's body. A control unit for controlling the entire process, in particular wirelessly, may be further provided. The breast implant may further have a rigid back plate, to which at least one chamber is fixedly connected, to provide stiffness giving the breast implant a basic _{contour which is maintained throughout any shape changes of the breast implant. Furthermore, in order to improve the overall appearance} of the breast implant, the part of the breast implant's outer wall facing away from the patient's chest may comprise a compartment filled with _{a soft material, such as silicone. Thus, the breast implant system disclosed in WO 2009/095259 A1 offers already a great variety of options} _{for changing the shape and the size of a breast implant after its implantation. The changes can be easily carried out and controlled by the} patient, without any medical practitioner being involved. _{[007] Further improvements of these breast implant systems are disclosed in WO 2011/006901 A1. According to one aspect, at least one} _{element and preferably two or more elements are displaceably arranged in a fluid chamber within the breast implant, i.e. they can be moved} _{relative to the fluid chamber and/or relative to each other between different spots within the fluid chamber so as to change the outer shape} _{of the breast implant. According to another aspect, a reservoir comprising a lubricating fluid., such as a liquid or gel, is connected to the fluid} _{chamber so as to allow the lubricating fluid to be supplied to the fluid chamber when the elements are supposed to be relocated within the} _{fluid chamber in order to reshape the breast implant. The lubricating fluid reduces surface friction, thereby facilitating the process of} relocating the elements within the fluid chamber. After the breast implant has been successfully reshaped, the lubricating fluid is removed _{from the fluid chamber back to the reservoir which is implanted remote from the breast implant, e.g. subcutaneously for manual compression.} _{[008] However, there is still room for improvement of those breast implant systems, such as in regards of} _{- facilitating the use of the system by the patient,} _{- facilitating implantation of the breast implant system in the patient’s body,} _{- reducing the complexity of the breast implant system,} _{- facilitating the reshaping process for the patient and} _{- making the breast implant system safer for the patient.} SUMMARY OF THE INVENTION _{[009] Thus, the present invention starts out from the disclosure of WO 2009/095259 A1 and, in particular, WO 2011/006901 A1 and seeks} to address the afore-mentioned issues. _{480SE - FIRST ASPECT: THROTTLED REFLOW (AUTOMATIC REFLOW)} _{[010] According to a first aspect of the present disclosure, the breast implant system comprises a plurality of chambers including a first} fluid chamber and a second fluid chamber. This includes the possibility that there is more than one first fluid chamber and/or more than one second fluid chamber. In the following, for sake of simplification, the mentioning of a first or a second fluid chamber is to be understood as also encompassing the situation where there is more than one first and/or more than one second fluid chamber. Said first and second fluid _{chambers are adapted for implantation in a human body with the first fluid chamber forming part of a breast implant. Furthermore, the first} and second fluid chambers are interconnected when implanted for fluid to be transferred between the first and second fluid chambers so as to change their respective fluid content. A fluid in the sense of the present disclosure encompasses any flowable material that can be exchanged between the first and second fluid chambers, in particular a gas, a liquid, a gel, a flowable foam or any combination thereof. The _{breast implant system further includes an energy storage. The energy storage is configured to store energy when fluid is transferred between} the first and second fluid chambers and is further configured to release the stored energy in a manner so as to re-transfer the transferred fluid between the first and second fluid chambers. Even further, the breast implant system comprises a flow control device which is configured to control fluid transfer between the first and second fluid chambers. Such flow control device, according to this first aspect of the present disclosure, comprises one of _{- a throttle which is configured to permit throttled re-transfer of the transferred fluid between the first and second fluid chambers} automatically over time, and _{- a piston configured such that fluid transfer between the first and second fluid chambers is realized by means of movement of the} piston, wherein friction acting on the piston counteracts the release of the stored energy and is adjusted or adjustable such that re- transfer of the transferred fluid between the first and second fluid chambers occurs automatically over time. _{[011] Thus, in both cases is the reflow of the fluid from the first fluid chamber or chambers contained in the breast implant to the second} fluid chamber or chambers, which may also be contained in the breast implant or may be arranged remote from the breast implant, automatic and occurs slowly over time. The advantage of the automatic reflow is that the patient does not need to take any action in order to bring the breast implant back to its “regular” shape, which facilitates the use of the system by the patient. _{[012] For example, where the first fluid chamber in the breast implant was inflated by means of fluid transferred to the first fluid chamber} _{from a – e.g. remotely implanted – second fluid chamber, the first fluid chamber will subsequently deflate automatically due to the release of} _{the stored energy from the energy storage, and such deflation will be slow due to the throttle in the flow path which throttles the reflow from} the first fluid chamber back to the second fluid chamber. The throttle may be chosen such that the time span from a maximum filling of the first fluid chamber to the minimum filling is one or more than one hour. The minimum filling may be reached when the energy stored in the energy storage is released completely or when the second fluid chamber cannot take up any further fluid. Similarly, when the second fluid chamber is contained in the breast implant along with the first fluid chamber, rather than being remotely implanted, and transfer of fluid from the second to the first fluid chamber changes the shape of the breast implant, e.g. from flat to high, then the shape of the breast implant will automatically return to the original shape, i.e. back to its flat shape, slowly over time. Of course, the situation may be exactly the opposite, i.e. such that the fluid is automatically re-transferred from the second fluid chamber to the first fluid chamber, so that the first fluid chamber automatically returns from an inflated state to a non-inflated or less-inflated state and, thus, the shape of the breast implant changes from flat to high. _{[013] In a more advanced embodiment, the throttle may be adjustable, e.g. by remote control or manually, so as to adjust the time span} _{within which the fluid re-transfers between the first and second chambers.} _{[014] Certainly, if the patient wishes to keep the breast implant in the changed shape for a longer time, he needs to pump the fluid again} between the first and second chambers. _{[015] The situation is basically the same in the case where the fluid transfer between the first and second fluid chambers is realized by} _{movement of a piston, the movement of which is restricted due to friction acting on the piston. The frictional force on the piston is – slightly} _{– lower than the force generated by the stored energy which is released from the energy storage so that the piston moves slowly under the} _{action of the released energy. Again, the frictional force acting on the piston and counteracting the release of the stored energy is preferably} _{adjusted so that the re-transfer of the transferred fluid from a maximum filling to the “regular” filling takes an hour or longer. In an advanced} embodiment, the frictional force acting on the piston may be adjustable, e.g. by remote control or by manual control. _{[016] The piston may be arranged in a cylinder which is arranged between the first and second fluid chambers, and the piston is movably} _{arranged in the cylinder such that the fluid transfer between the first and second fluid chambers is realized by means of movement of the} _{piston in the cylinder, thereby causing a fluid transfer from the first to the third and from the third to the second fluid chambers, and vice} versa. Such an arrangement is particularly suitable in the case where the piston is contained in the breast implant, such as in a rigid back _{wall of the breast implant. Preferably, also a motor for driving the piston may be contained therein, as will be explained in more detail further} below. _{[017] In the embodiment where the flow control device comprises the throttle, rather than the piston, a check valve may be provided} _{which is configured to permit free transfer of fluid between the first and second fluid chambers and prevent re-transfer of the transferred} _{fluid through the check valve. Thus, the patient may easily pump fluid between the first and second fluid chambers, e.g. from a remotely} implanted second fluid chamber to the first fluid chamber in the breast implant, whereas, once such fluid transfer is terminated, the check _{valve closes and automatic reflow of the fluid occurs only through the throttle.} _{[018] In all embodiments according to this and the flowing aspects of the present disclosure, the second fluid chamber may be implanted} in the breast implant along with the first fluid chamber or, alternatively, the second fluid chamber may be implanted remotely from the breast implant, e.g. underneath the patient’s minor pectoralis muscle next to the patient’s thorax or between the patient’s minor and major pectoralis _{muscles, in the patient’s abdominal cavity, or in the chest area, preferably outside the patient’s thorax.} _{481SE - SECOND ASPECT: REFLOW SWITCH (AUTOMATIC REFLOW)} _{[019] According to a second aspect of the present disclosure, again, the breast implant system comprises a plurality of chambers} including a first fluid chamber and a second fluid chamber, which includes the possibility that there is more than one first fluid chamber and/or more than one second fluid chamber. Said first and second fluid chambers are adapted for implantation in a human body with the first fluid chamber forming part of a breast implant, and the first and second fluid chambers are interconnected when implanted for fluid to be transferred between the first and second fluid chambers so as to change their respective fluid content. Also the breast implant system _{according to this second aspect includes an energy storage which is configured to store energy when fluid is transferred between the first} and second fluid chambers and which is further configured to release the stored energy in a manner so as to re-transfer the transferred fluid between the first and second fluid chambers. Even further, the breast implant system according to this second aspect also comprises a flow control device which is configured to control fluid transfer between the first and second fluid chambers. However, according to this second aspect of the present disclosure, the flow control device comprises a switch which is operable so as to switch the flow control device between a first state, in which the flow control device is configured to permit free transfer of fluid between the first and second fluid chambers in a first direction while preventing transfer of fluid in a second direction opposite to the first direction, and a second state, in which the flow _{control device is configured to permit re-transfer of the transferred fluid between the first and second fluid chambers in the second direction.} _{[020] The breast implant system according to the second aspect substantially facilitates the use of the system by the patient. With the} switch in the first state, transfer between the first and second chambers is easily possible, whereas backflow is prevented. For instance, a check valve may be provided in the flow control device in order to provide such function. As an example, the patient may inflate the first chamber in the breast implant with fluid from a remotely implanted second fluid chamber. If the patient wishes that the breast implant returns _{to its original state, the patient simply needs to actuate the switch such that it assumes its second state so that the fluid flows back between} the first and second fluid chambers in the second direction due to the release of the energy previously stored in the energy storage device when the fluid was transferred in the first direction. Accordingly, a single action of the patient is sufficient to switch the flow control device _{to its second state, the release state. The flow control device remains in this state without any further action so that the fluid can flow back} until either all of the energy stored in the energy storage is released or until the respective fluid chamber receiving the re-transferred fluid takes no further fluid. _{[021] The switch may be pressure operable in the opposite direction, i.e. from the second state, in which the fluid is permitted to flow in} _{the second direction (release), to the first state, in which the fluid is free to flow in the first direction and prevented from flowing backward.} For instance, when a pressure is built up in order to pump fluid between the first and second chambers in said first direction, such pressure _{is applied to the pressure operable switch so as to switch the flow control device into the first state in which the fluid can freely flow in the} first direction but is prevented from reflowing in the opposite, second direction. _{[022] According to a preferred embodiment, the flow control device is configured to permit unthrottled re-transfer of the transferred} _{fluid in the second direction, i.e. when the flow control device is in the second state. This way, the reshaping of the breast implant to its regular} shape occurs relatively quickly. _{[023] Further, in some situations it may be more pleasant for the patient if the automatic reflow occurs slowly over time, e.g. in situations} _{where such reflow causes stretching of the patient’s skin above the implant and where the skin needs time to adapt to such stretching.} Therefore, according to another preferred embodiment, the flow control device may comprise a throttle which is configured to permit throttled re-transfer of the transferred fluid between the first and second fluid chambers, i.e. in the second direction, automatically over time. _{[024] An actuator of the switch may be mounted subcutaneously so as to be operable manually. Such an actuator may be easy to use for} _{the patient and allows the entire system to be made purely mechanical if, e.g., pumping of the fluid in the opposite, first direction is also} manual. Thus, the switch is preferably a purely mechanical switch. More preferably, the mechanical switch is a hydraulic switch because hydraulic pressure can be easily transferred through corresponding pressure lines over longer distances, such as from a subcutaneously implanted compressible fluid chamber to the flow control device. _{[025] In an alternative preferred embodiment, the switch may comprise an electric switch, i.e. a switch which is electrically actuated.} This may be more convenient for the patient, in particular if such actuation is initiated from outside the patient’s body by wireless remote control. _{[026] There are various ways of how the energy storage may be configured to store energy in an energy storage when fluid is transferred} between the first and second fluid chambers. According to a first embodiment, the energy storage comprises an elastic wall which surrounds one of the first and second fluid chambers at least partly. The elastic wall is configured to expand when fluid is transferred from the respective other one of the first and second fluid chambers into said one of the first and second fluid chambers. For instance, the fluid chamber with the _{elastic wall may be of balloon-type. Accordingly, the wall stores the energy which, due to the elastic properties of the wall, causes a reaction} force on the fluid transferred into the fluid chamber so as to urge the fluid to flow back to the respective other fluid chamber. _{[027] In another embodiment, the energy storage, which is configured to store the energy when fluid is transferred between the first} _{and second fluid chambers, may comprise a resilient element, and the resilient element may be configured to expand one of the first and} second fluid chambers. For instance, the resilient element may be a spring, such as a coil spring. This way, the fluid chamber containing the resilient element automatically expands and, thereby, draws fluid from the respective other fluid chamber. Of course, the respective other fluid chamber may be surrounded at least partly by an elastic wall, as explained above, so that the force generated by the elastic wall, on the _{one hand, and the force generated by the resilient element add up. In this case, the resilient element may be correspondingly down-sized.} _{[028] Preferably, the resilient element may be configured to expand the second fluid chamber, i.e. the fluid chamber which may be} _{arranged remotely from the breast implant, so that the breast implant in its “regular” state is relaxed.} _{[029] As mentioned above, one or more elements may be displaceably arranged in the first fluid chamber, which is the fluid chamber} contained in the breast implant. In this situation, the second fluid chamber may comprise a lubricating fluid so as to allow lubricating fluid to be supplied from the second fluid chamber to the first fluid chamber in order to reduce surface friction between an outer surface of the one _{or more elements and surfaces contacting the outer surface of the one or more elements. That is, it is advantageous also for a breast implant} _{system of such lubricating type to provide the automatic reflow function described above, i.e. with or without the switch, throttled or} unthrottled. For instance, the lubricating fluid may be actively pumped from a remotely implanted reservoir formed by the second fluid chamber into the first fluid chamber of the breast implant, whereas the lubricating fluid may automatically return into the reservoir after the reshaping of the breast implant has been completed. _{[030] However, as mentioned above, the second fluid chamber does not need to be implanted separate from the breast implant. Instead,} _{the first and second fluid chambers may each be contained in the breast implant, which means that the exchange of fluid between the first} _{and second fluid chambers results in a change of the shape of the breast implant, but not necessarily in a change of the size of the breast} implant. _{[031] Furthermore, the automatic reflow function may likewise be implemented in those implants which have a variable shape and a} (slightly) variable volume, but a constant mass, which type of breast implant is likewise described in WO 2011/006901 A1. In this type of implant, the first and second fluid chambers form part of the breast implant and each comprise an incompressible fluid, wherein a third fluid chamber _{also forming part of the breast implant comprises a compressible fluid. Due to the specific configuration of the first and second fluid chambers,} _{an exchange of the incompressible fluid between the first and second fluid chambers results in an increase of pressure of the compressible} fluid within the third fluid chamber so that the shape and volume of the overall breast implant changes while its mass remains constant. In this type of breast implant, the increase of pressure within the first fluid chamber constitutes the energy storage which drives the automatic _{reflow function. Again, a switch for activating the reflow function may or may not be provided, and the automatic reflow may be throttled or} unthrottled. _{[032] Furthermore, the automatic reflow function may be combined with a servo system, which is generally described in WO 2011/006901} _{A1. In this case, a third fluid chamber cooperates with the first and second fluid chambers such that when fluid is exchanged between the first} and second fluid chambers, the fluid in the third fluid chamber is caused to move, wherein the amount of fluid moved in the third fluid chamber is different to the amount of fluid exchange between the first and second fluid chambers. _{[033] According to one preferred embodiment of such servo system, the third fluid chamber comprises sub-chambers which are} interconnected. At least one of the first and second fluid chambers is operatively connected to at least one of the sub-chambers and is adapted to expand this sub-chamber when fluid is exchanged between the first and second fluid chambers. Fluid will then flow between the sub-chambers into the expanded sub-chamber, and the amount of fluid flow can be substantially different to the amount of fluid exchange between the first and second fluid chambers. There are various alternative ways of realizing such servo system in the breast implant system. In this context, it is preferable to provide a spring or other kind of resilient element to urge the third fluid chamber or at least one of the sub- _{chambers thereof into a state of minimum or maximum volume, i.e. into a normally small or a normally large state. Such spring or resilient} element constitutes the energy storage for the automatic reflow function described above. Energy is then only needed to exchange fluid between the first and second fluid chambers in one direction, whereas the necessary force required to exchange the fluid in the opposite _{direction is provided by the resilient force, which force can be released e.g. by actuation of a switch and/or in a throttled manner, as likewise} described above. _{[034] The servo system can be designed as a reverse servo system to the extent that only a little amount of fluid needs to be exchanged} between the sub-chambers of the third fluid chamber in order to achieve a relatively large amount of fluid exchange between the first and second chambers. This means that a relatively large force but small stroke is needed to achieve the relatively large amount of fluid exchange between the first and second fluid chambers. This is particularly convenient where one of the sub-chambers of the third fluid chamber is provided for subcutaneous implantation so as to be manually compressible by the patient from the outside of the patient’s body. Thus, the subcutaneously arranged compressible sub-chamber may have a relatively small volume and will therefore not adversely affect the patient’s visual appearance, with the negative side effect that the patient will have to apply a relatively large force on the relatively small subcutaneous sub-chamber in order to achieve the desired, relatively large volume change in the breast implant. _{[035] In cases where the breast implant system does not include a servo system or, thus, any sub-chambers of any third fluid chamber,} the remotely implantable second sub-chamber may itself be arranged for subcutaneous implantation so as to be operable by the patient from outside the patient’s body. _{483SE - THIRD ASPECT: MOTOR/PUMP IN BREAST IMPLANT + ENERGY RECEIVER IN STERNUM} _{[036] According to a third aspect of the present disclosure, again, the breast implant system comprises a plurality of chambers including} a first fluid chamber and a second fluid chamber, which includes the possibility that there is more than one first fluid chamber and/or more than one second fluid chamber. Said first and second fluid chambers are adapted for implantation in a human body with the first fluid chamber forming part of a breast implant, and the first and second fluid chambers are interconnected when implanted for fluid to be transferred between the first and second fluid chambers so as to change their respective fluid content. According to this third aspect of the present disclosure, there is provided an energy source for supplying energy to at least one energy consuming part of the breast implant system, such as to a pump or to a motor, which may be a motor for driving a pump. The energy source comprises a wireless energy transmitter configured to wirelessly transmit energy from outside the patient’s body and one or more than one energy receiver configured to receive the wirelessly transmitted energy from the wireless energy transmitter. The one or more than one energy receiver is configured for implantation within the patient’s body above the patient’s sternum. _{483SE - METHOD OF IMPLANTATION (THIRD ASPECT)} _{[037] Accordingly, a corresponding surgical method of implanting a breast implant system in a patient’s body comprises the following} steps: _{- cutting an opening in the skin in the breast area,} _{- dissecting the area,} _{- placing at least a part of the breast implant system in the dissected area, wherein the breast implant system comprises:} _{- a plurality of chambers including a first fluid chamber and a second fluid chamber, said first and second fluid chambers being} _{adapted for implantation in a human body with the first fluid chamber forming part of a breast implant, said first and second fluid} _{chambers being interconnected when implanted for fluid to be transferred between the first and second fluid chambers so as to change} their respective fluid content, -_{at least one energy consuming part which forms part of the breast implant and} _{- an energy source for supplying energy to the at least one energy consuming part, wherein the energy source comprises a wireless} _{energy transmitter configured to wirelessly transmit energy from outside the patient’s body and an energy receiver configured to} receive the wirelessly transmitted energy from the wireless energy transmitter, -_{placing the energy receiver above the patient’s sternum and} _{- suturing the skin.} _{[038] A surgical method of laparoscopic implantation of a breast implant system in a patient’s body comprises the steps of:} _{- inserting a needle like tube into the breast area of the patient’s body,} _{- using the needle like tube to fill the breast area with gas thereby expanding a cavity,} _{- advancing at least two laparoscopic trocars in the patient’s body,} _{- inserting a camera through one of the trocars,} _{- inserting at least one dissecting tool through another one of the trocars and dissecting an area of at least one portion of the breast} area of the patient, and _{- placing at least a part of a breast implant system in the dissected area, wherein the breast implant system comprises:} _{- a plurality of chambers including a first fluid chamber and a second fluid chamber, said first and second fluid chambers being} adapted for implantation in a human body with the first fluid chamber forming part of a breast implant, said first and second fluid c_{hambers being interconnected when implanted for fluid to be transferred between the first and second fluid chambers so as to change} their respective fluid content, -_{at least one energy consuming part which forms part of the breast implant and} _{- an energy source for supplying energy to the at least one energy consuming part, wherein the energy source comprises a wireless} energy transmitter configured to wirelessly transmit energy from outside the patient’s body and an energy receiver configured to receive the wirelessly transmitted energy from the wireless energy transmitter, and _{- placing the energy receiver above the patient’s sternum.} _{[039] Placing the energy receiver above the patient’s sternum provides certain advantages. The patient’s skin does not move much in} the region of the sternum so that the danger of possible damage of the receiver is accordingly reduced. Further, the sternum provides a strong support to the receiver which facilitates the use of the system when the patient presses the transmitter against the skin above the _{receiver. Finally, the sternum is near the breast so that distances between the receiver and the breast implant are short. The amount of} surgery needed to install the breast implant system in the patient is accordingly reduced. _{[040] There may be provided a separate energy receiver for the one or the other or for each of the energy consuming parts. These} separate energy receivers may be activated individually by the patient, depending on the functionality of the breast implant which the patient wishes to activate, e.g. inflating, deflating, etc. _{[041] In order to reduce the complexity even further, it is preferred to provide the energy consuming part or parts of the system in the} _{breast implant. More preferably, the breast implant is provided with a rigid back wall which is configured for being placed adjacent the patient’s} _{thorax, and the energy consuming part is contained in or on the back wall. The energy consuming part may be an electrically driven pump or} an electrically driven motor, such as an electric motor for driving a mechanical pump. Of particular advantage in this context are piezoelectric pumps and motors because of their relatively small size which makes them particularly suitable for arranging them on or, in particular, in the rigid back wall of the breast implant. With the energy consuming part forming part of the breast implant, it may be possible to implant the breast implant system as two pieces, namely the breast implant with the energy consuming part, on the one hand, and the receiver, on the other hand, the receiver preferably being conductively connected to the energy consuming part. _{[042] The energy source may further comprise an energy storage, such as a battery or an accumulator, connected to the energy} _{consuming part for storing the wirelessly transmitted energy. Preferably, this energy storage is likewise contained on or, more preferably,} _{in the back wall of the breast implant.} _{[043] Alternatively, the energy source may comprise an implantable energy transforming device for transforming the wirelessly} transmitted energy into electric energy for direct use by the energy consuming part. For instance, the receiver may be configured as a _{transceiver. Thus, when the patient holds the energy transmitter above the energy receiver or transceiver, such energy is transformed and} _{directly consumed by the motor or pump so as to correspondingly change the shape and/or volume of the breast implant immediately without} the need for the patient to do anything further. Reshaping of the breast implant may, again, occur automatically by actuating the above- mentioned switch and/or through a throttle. _{[044] Furthermore, a control unit may be provided for directly or indirectly controlling one or more elements of the breast implant} system, preferably by wireless remote control. The control unit may be adapted to control the exchange of fluid between the first and second _{fluid chambers. This may include the operation of a flow control device so as to switch the flow control device to an automatic reflow mode,} as discussed above. _{484SE - FOURTH ASPECT: VISCOPLASTIC OR VISCOELASTIC FILLING} _{[045] According to a fourth aspect of the present disclosure, there is provided a breast implant for implantation in a patient’s body, which} _{comprises at least one fluid chamber with a flexible outer shape and a filling in the fluid chamber. The filling comprises at least one of a} Bingham fluid, a viscoelastic material and a memory foam. _{[046] Each of these materials can be chosen such that the breast implant can be reshaped manually by compressing the breast implant} so that it assumes the desired shape. While the material of the Bingham fluid can be chosen such that the breast implant maintains its shape after being reshaped, on the one hand, or such that the breast implant slowly changes back to its regular shape due to gravitational forces, the viscoelastic material as well as the memory foam have the effect that the breast implant, after being reshaped manually from the outside of the implant, returns to its regular shape automatically due to internally acting forces which result from the elasticity of such materials. Thus, in either case is it relatively easy for the patient to change the shape of the implant to a desired form and return the shape of the implant to its original form or similar to its original form. _{[047] As the Bingham fluid, preferably a Bingham fluid is chosen which behaves, at a normal body temperature of 37 °C, as a rigid body} at stresses below a yield stress and starts to flow at stresses exceeding the yield stress. According to this fourth aspect of the present disclosure, the yield stress of the employed Bingham fluid is preferably such that, on the one hand, the Bingham fluid does not flow under its _{own weight and, on the other hand, the Bingham fluid can be made to flow when the fluid chamber is manually compressed and deformed from} outside the breast implant. As a result, the shape of the breast implant can be changed post-operatively by manually compressing the breast _{implant and, preferably, remains in the changed shape unless forces exceeding gravitational forces act on the breast implant.} _{[048] The viscoelastic material exhibits both viscous and elastic characteristics. The shape of the breast implant, according to this fourth} _{aspect of the present disclosure, is predetermined by the viscoelastic material of the filling in the fluid chamber. Thus, when the breast implant} is deformed so that the predetermined shape of the breast implant changes, the breast implant does not immediately return to its predetermined shape, due to the viscosity of the material, and returns to the predetermined shape only very slowly over time due to the elasticity of the material. _{[049] As regards the memory foam, this is a particular viscoelastic material and may be made e.g. of polyurethane, such as a low-} resilience polyurethane foam (LRPu). A memory foam is an open cell foam providing a matrix through which a fluid, in particular air, can flow. This matrix provides a network effect which creates a force working to restore the foam’s original structure when it is deformed, thereby providing elasticity to the foam. The viscose effects of the memory foam are a combination of pneumatic, adhesive and relaxation effects. The pneumatic effect is caused by the time for the fluid to flow through the foam’s porous structure. The adhesive effect is caused by the stickiness of the surfaces within the foam when the internal pores within the foam are pressed together. And the relaxation effect, which is the strongest of the three forces working against the restoration of the foam towards its original form, is caused by the foam’s material being near its _{glass transition temperature which limits its mobility and slows the return of the foam to its original form once the applied pressure is} removed. _{[050] Since the effects are temperature-dependent, a memory foam is preferably chosen which provides the desired effect at a} _{temperature of about 37 °C. In this regard, smaller pores lead to a higher internal surface area and reduced air flow, increasing the adhesion} and pneumatic effects. Thus, the foam’s properties can be controlled by changing its cell structure and porosity. The glass transition temperature can be modulated with additives in the foam’s material. _{[051] Accordingly, when the breast implant is deformed by the patient from outside the breast, the memory foam within the fluid chamber} of the breast implant deforms accordingly and this results in a corresponding reshaping of the breast implant. Over time, the shape of the breast implant will automatically return to its original form. _{[052] However, as mentioned above, the pneumatic and adhesive effects slowing down the regeneration of the foam’s original structure} _{requires the fluid to be pressed out of the foam, thereby reducing the pores in the foam and increasing the adhesive effect caused by the} _{stickiness of the surfaces in the foam being pressed together. Therefore, according to a preferred embodiment, the fluid chamber of the} _{breast implant forms a first fluid chamber which is connected to a second fluid chamber. Then, compression of the fluid chamber causes fluid} _{to flow from the fluid chamber out of the memory foam into the second fluid chamber so that the volume of the breast implanted decreases.} _{The second fluid chamber is accordingly implanted remote from the breast implant so as to form a reservoir for the first fluid chamber, and} _{may be realized e.g. as a flat cushion underneath the pectoralis muscle. This way, the shape of the breast implant does not only change, but} the volume of the breast implant is also reduced when the breast implant is manually compressed from outside the breast or when fluid is _{actively withdrawing from the memory foam into the remotely implanted second fluid chamber, whereas restoration of the breast implant to} its original form is accordingly very slow. _{[053] In addition, a flow control device may be arranged between the first fluid chamber, i.e. the fluid chamber in the breast implant, and} _{the remotely implanted second fluid chamber. Such flow control device may be configured in a way as described above in relation to the first} and second aspects, i.e. comprising or not comprising a switch and/or permitting throttled or unthrottled reflow. _{487SE - FIFTH ASPECT: LUBRICATION WITH THIXOTROPIC FLUID} _{[054] According to a fifth aspect of the present disclosure, there is again provided a breast implant for implantation in a patient’s body,} _{which comprises at least one fluid chamber with a flexible outer shape and a filling in the fluid chamber. However, in this fifth aspect, the fluid} _{chamber is filled with at least one element displaceably arranged in the fluid chamber, preferably in the form of a plurality of regular or} _{irregular spheres, and a lubricating fluid which fills spaces in the fluid chamber, in particular spaces between those spheres. As in the other} _{embodiments, the lubricating fluid is provided for reducing surface friction, namely here between the spheres and surfaces contacting the} spheres. According to this fifth aspect of the present disclosure, the lubricating fluid is a thixotropic fluid. This means that the lubricating fluid has a time-dependent shear thinning property. _{[055] More specifically, some gels or fluids that are thick or viscous under static conditions become thinner, i.e. less viscous, when they} are subject to shear-stresses, such as by shaking, agitation, walking and the like. Preferably, the thixotropic fluid is chosen such that it bonds _{the one or more elements or spheres in the fluid chamber to surfaces contacting the one or more elements or spheres, such as surfaces of} _{neighboring elements or spheres or the surface of an inner wall of the fluid chamber. Upon compressing and walking of the breast implant,} the thixotropic fluid becomes less viscous, i.e. fluent, so that the breast implant can be reshaped. When the patient is satisfied with the _{reshaped form of the breast implant and terminates the compressing and walking process, the viscosity of the thixotropic fluid increases} again and finally bonds the elements or spheres together at their new position. _{[056] The more elements or spheres are present in the breast implant, the better is the behavior. Therefore, the fluid chamber contains} preferably one thousand or more of those spheres. _{485SE - SIXTH ASPECT: RECESSES FOR LUBRICATION} _{[057] According to a sixth aspect of the present disclosure, the breast implant system comprises a breast implant with a first fluid} chamber which has a flexible outer shape and at least one element displaceably contained therein. A port in this first fluid chamber is configured for supplying a lubricating fluid into the first fluid chamber in order to reduce surface friction between an outer surface of the _{elements and surfaces contacting the outer surface of the elements. According to this sixth aspect of the present disclosure, an inner surface} _{of the first fluid chamber and/or the outer surface of the elements has one or more recesses. The purpose of the recesses is to facilitate} distribution of the lubricating fluid within the first fluid chamber. This is particularly helpful when the lubricating fluid is being supplied to the _{first fluid chamber and/or removed from the first fluid chamber through the port. The fourth aspect of the present disclosure is combinable} with all other aspects disclosed herein. _{[058] The recesses may be provided in the form of grooves so that the lubricating fluid may flow along the grooves. Preferably, at least} some of the grooves are connected to one or more other grooves so that the fluid can spread between the grooves and, thus, distribute more quickly. _{[059] More preferably, the grooves may extend from the port along the inner surface of the first fluid chamber. Thus, the lubricating fluid} injected into the first fluid chamber can immediately flow into the grooves and along the grooves, preferably to the opposite side of the breast implant, so that it distributes quickly. _{[060] Alternatively or in addition, at least some of the recesses may be provided in the form of valleys between elevations. This way,} _{space is provided between the elements contained in the fluid chamber and the inner wall of the fluid chamber so as to facilitate distribution} of the lubricating fluid in the first fluid chamber. As mentioned, the recesses, e.g. in the form of grooves or valleys, may likewise be provided on an outer surface of the one or more elements which are displaceably contained in the first fluid chamber. Preferably, the elements are numerous, such as one thousand or more, and take the form of regular or irregular spheres. _{[061] As regards the port through which the lubricating fluid is supplied into the first fluid chamber, such port may connect the first fluid} chamber to a second fluid chamber which forms a reservoir for the lubricating fluid, as already discussed above, wherein the second fluid chamber storing the lubricating fluid is preferably remotely implanted in the patient’s body. _{[062] In a preferred embodiment, however, the port is a self-sealing injection port which is arranged in or on the first fluid chamber at} a location which is easily reachable, when implanted, and pierceable with a syringe from outside the breast implant, as will be discussed next in relation to the sixth aspect of the present disclosure. _{488SE - SEVENTH ASPECT: INJECTION PORT IN BREAST IMPLANT} _{[063] According to a seventh aspect of the present disclosure, again, the breast implant system comprises a breast implant with a first} _{fluid chamber which has a flexible outer shape and at least one element displaceably contained therein, wherein a port is provided in this first} _{fluid chamber and configured for supplying a lubricating fluid into the first fluid chamber in order to reduce surface friction between an outer} surface of the elements and surfaces contacting the outer surface of the elements. According to this seventh aspect of the present disclosure, the port is a self-sealing injection port. This port was already referred to above, and it is arranged in or on the first fluid chamber at a location so as to be pierceable, when implanted in a patient’s breast, with a syringe from outside the breast implant. The seventh aspect of the present disclosure is combinable with all other aspects disclosed herein. _{[064] In particular, the port may be sensed tactilely through the patient’s skin and the patient can directly inject and withdraw the} lubricating fluid into and from the first fluid chamber of the implant using the syringe. A second fluid chamber as a reservoir for the lubricating fluid is not needed. However, a second fluid chamber may be provided for exchanging fluid between such second fluid chamber and elements contained in the first fluid chamber in order to decrease or increase the size of the breast implant. _{482SE - EIGHTH ASPECT: PIEZOELECTRIC MOTOR AND/OR PUMP} _{[065] According to an eighth aspect of the present disclosure, again, the breast implant system comprises a plurality of chambers} including a first fluid chamber and a second fluid chamber, which includes the possibility that there is more than one first fluid chamber and/or more than one second fluid chamber. Said first and second fluid chambers are adapted for implantation in a human body with the first _{fluid chamber forming part of a breast implant, and the first and second fluid chambers are interconnected when implanted for fluid to be} transferred between the first and second fluid chambers so as to change their respective fluid content. According to this eighth aspect of the present disclosure, the breast implant system comprises at least one piezoelectric motor and/or at least one piezoelectric pump. The eighth aspect of the present disclosure is combinable with the first to fourth, sixth and seventh aspects disclosed herein. _{[066] Accordingly, at least one of the motor or motors of any one of the breast implant systems disclosed herein may be a piezoelectric} _{motor and/or at least one of the pump or pumps of such systems may be a piezoelectric pump.} _{[067] Piezoelectric motors and piezoelectric pumps are advantageous in that they may have high precision, low power consumption, may} be made small and lightweight, may provide high motion accuracy, and may be made from materials which are relatively immune to interference, such as electromagnetic interference. In particular, piezoelectric motors can be manufactured without magnetic and/or metallic parts. Thus, piezoelectric motors and pumps can be made MRI-safe, meaning that the patient can undergo Magnetic Resonance Imaging (MRI) while having the piezo motor implanted. PIEZOELECTRIC MOTOR _{[068] According to a first variant, the piezoelectric motor is a piezoelectric inchworm motor. According to a second variant, the} piezoelectric motor is a piezoelectric inertial motor. According to a third variant, the piezoelectric motor is a piezoelectric walk-drive motor. According to a fourth variant, the piezoelectric motor is a piezoelectric ultrasonic motor. _{[069] The piezoelectric motor may be a linear piezoelectric motor, which may operate with at least one of: a speed in the range of 1 mm/s} _{– 10 mm/s, a stroke length in the range of 4 mm – 30 mm, and a force in the range of 2 N – 30 N, or the piezoelectric motor may be a rotary} _{piezoelectric motor, which may operate with at least one of: a rotational speed in the range of 1 mrad/s – 100 mrad/s and a torque in the} _{range of 100 Nmm – 900 Nmm.} _{[070] The piezoelectric ultrasonic motor may be a linear piezoelectric ultrasonic motor, which may operate with at least one of: a speed} _{in the range of 4 mm/s – 100 mm/s, a stroke length in the range of 4 mm – 30 mm, and a force in the range of 0.006 N – 40 N, or it may be} _{a rotary piezoelectric ultrasonic motor which may operate with at least one of: a rotational speed in the range of 10 mrad/s – 10,000 mrad/s,} _{and a torque in the range of 20 Nmm – 450 Nmm. Although piezoelectric motors have a relatively complex structure and control system, they} may feature a linear resolution as low as 0.21 µm. _{[071] According to one sub-aspect, the piezoelectric motor comprises at least one bimorph piezoelectric actuator.} _{[072] The piezoelectric motor according to any one of the variants is preferably substantially non-magnetic and/or non-metallic.} _{[073] In all of the variants, the piezoelectric motor may be a reversible piezoelectric motor.} _{[074] The piezoelectric motor may form part of a drive unit for driving the at least one infusion needle.} _{[075] The piezoelectric motor may be configured to drive a pump for injecting a substance into the patient’s body via the at least one} infusion needle. PIEZOELECTRIC PUMP _{[076] According to one embodiment, a piezoelectric pump is provided comprising a first wall portion, a first diaphragm, a first chamber} and a driving element. The first diaphragm and the first wall portion enclose the first chamber. The first wall portion comprises an inlet _{configured to connect the first chamber to a first inlet reservoir and an outlet configured to connect the first chamber to a first outlet} reservoir. The first diaphragm is configured to bend in response to operation of the driving element, and the driving element comprises a piezoelectric actuator, or is configured to be operated by a piezoelectric motor. Piezoelectric pumps are advantageous in that they are miniaturized and energy-efficient implantable devices. Piezoelectric pumps may precisely deliver fluid with a flow rate in the range of 0.01 _{ml/min to 35 ml/min, for the present application preferably in the upper range of 10 ml/min to 35 ml/min, and a pressure in the range of} 0.2 kPa to 36 kPa, wherein for the present application a pressure in the lower range between 0.2 kPa and 1 kPa, preferably close to 0.2 kPa, may be sufficient. _{[077] According to one embodiment, a piezoelectric pump is provided wherein the inlet of the first wall portion comprises an inlet valve} and the outlet of the first wall portion comprises an outlet valve. Any of the inlet valve of the first wall portion and outlet valve of the first wall _{portion may be a check valve or an active valve. The check valve may be a ball valve. The inlet valve and outlet valve are useful to stabilize the} _{flow rate in the first chamber.} _{[078] According to one embodiment, the inlet of the first wall portion comprises an inlet static element and the outlet of the first wall} portion comprises an outlet static element, wherein any of the inlet static element and outlet static element is configured to act as a nozzle _{or a diffuser. Nozzles and diffusers are advantageous in that they are more resistant to wear and fatigue failure as compared to check valves} and active valves. _{[079] According to one embodiment, the first diaphragm comprises a first movable wall portion. The first movable wall portion may} comprise elevated and lowered portions, wherein the elevated and lowered portions enable at least one of compression and expansion for moving the first movable wall portion. The first movable wall portion may comprise a substantially stiff portion. The first movable wall portion _{may comprise a bellows. The bellows may comprise metal. The bellows may comprise at least one of an oval cross section, an elliptic cross-} section and a circular cross-section. Metals are generally dense, which is advantageous as fluids do not diffuse through metals as easily. This reduces the risk that fluid diffuses from the first chamber or that fluids diffuse into the first chamber. _{[080] According to one embodiment, a piezoelectric pump is provided which further comprises an auxiliary wall portion and an auxiliary} chamber sealed from the first chamber. The auxiliary wall portion and the first diaphragm enclose the auxiliary chamber. The sealing of the auxiliary chamber from first chamber is advantageous in that a component unsuitable to be in contact with the fluid in the first chamber may be hosted by the auxiliary chamber. Such a component may be the driving element. _{[081] According to one embodiment, a piezoelectric pump is provided which further comprises an auxiliary wall portion, an auxiliary} chamber sealed from the first chamber, and an auxiliary diaphragm configured to bend in the same direction as the first diaphragm in response to operation of the driving element. The auxiliary wall portion and the auxiliary diaphragm enclose the auxiliary chamber. _{[082] According to one embodiment, the auxiliary chamber is configured to be connected to a pressure adapter enabling variation of} pressure in the auxiliary chamber. The pressure adapter may comprise an elastic portion having a surface area, and the elastic portion may be configured to maintain substantially the same surface area while enabling variation of pressure in the auxiliary chamber. This is advantageous in that a fibrotic tissue which at least partially covers the elastic portion may easily adapt to the elastic portion. _{[083] According to one embodiment, a piezoelectric pump is provided which further comprises a second wall portion, a second diaphragm} and a second chamber. The second diaphragm and the second wall portion enclose the second chamber. The second wall portion comprises _{an inlet, configured to connect the second chamber to a second inlet reservoir, and an outlet, configured to connect the second chamber to} a second outlet reservoir. The second diaphragm is configured to bend in the same direction as the first diaphragm in response to operation of the driving element. The embodiment is advantageous in that the piezoelectric pump is configured to be operated in a double mode. _{[084] According to one embodiment, the inlet of the second wall portion comprises an inlet valve and the outlet of the second wall portion} comprises an outlet valve. Any of the inlet valve of the second wall portion and outlet valve of the second wall portion may be a check valve or an active valve. The check valve may be a ball valve. The inlet valve and outlet valve are useful to stabilize the flow rate in the second chamber. _{[085] According to one embodiment, the inlet of the second wall portion comprises an inlet static element and the outlet of the second} wall portion comprises an outlet static element, wherein any of the inlet static element and outlet static element is configured to act as a nozzle or a diffuser. Nozzles and diffusers are advantageous in that they are more resistant to wear and fatigue failure as compared to check valves and active valves. _{[086] According to one embodiment, the piezoelectric pump comprises at least two portions connected in series, wherein each portion} is a piezoelectric pump. The series connection allows for larger pressure compared to piezoelectric pumps in which fluid is transferred from an inlet to an outlet reservoir via a single chamber. _{[087] According to one embodiment, the piezoelectric pump comprises at least two portions connected in series, wherein each portion} is a piezoelectric pump configured to be operated in a double mode. The series connection allows for larger pressure as compared to _{piezoelectric pumps configured to be operated in a double mode in which a first fluid is transferred from a first inlet reservoir to a first outlet} reservoir via a single first chamber and a second fluid is transferred from a second inlet reservoir to a second outlet reservoir via a single second chamber. _{[088] According to one embodiment, the piezoelectric pump comprises at least two portions connected in parallel, wherein each portion} is a piezoelectric pump. The parallel connection allows for a higher flow rate as compared to piezoelectric pumps in which the inlet reservoir is configured to be connected to a single inlet and the outlet reservoir is configured to be connected to a single outlet. _{[089] According to one embodiment, the piezoelectric pump comprises at least two portions connected in parallel, wherein each portion} is a piezoelectric pump configured to be operated in a double mode. The parallel connection allows for a higher flow rate as compared to piezoelectric pumps configured to be operated in a double mode in which the first inlet reservoir and second inlet reservoir are configured to be connected to a single first inlet and single second inlet, respectively, and the first outlet reservoir and second outlet reservoir are _{configured to be connected to a single first outlet and single second outlet, respectively.} _{[090] According to one embodiment, the medical device further comprises a controller configured to control the piezoelectric pump.} _{[091] According to one embodiment, the medical device further comprises a sensor configured to measure a parameter of the} piezoelectric pump, and a feedback unit. The sensor is further configured to transmit the measured parameter to the feedback unit. The feedback unit is configured to transmit a conditioning signal to the controller based on the measured parameter received from the sensor _{and based on a set value of the parameter. The controller is configured to adjust the control of the piezoelectric pump based on the} conditioning signal received from the feedback unit in order for the measured parameter to achieve the set value. _{[092] The invention will now be described in more detail in context with some preferred embodiments of the invention as shown in the} accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS _{[093] Figs. 1A and 1B show a breast implant system according to a first embodiment of the present disclosure,} _{[094] Figs. 2A and 2B show a breast implant system according to a second embodiment of the present disclosure,} _{[095] Figs. 3A and 3B show a breast implant system according to a third embodiment of the present disclosure,} _{[096] Figs. 4A and 4B show a breast implant system according to a fourth embodiment of the present disclosure,} _{[097] Figs. 5A to 5C show a breast implant system according to a fifth embodiment of the present disclosure,} _{[098] Figs.6A to 5C show a breast implant system according to an sixth embodiment of the present disclosure,} _{[099] Figs. 7A to 7C show a breast implant system according to a seventh embodiment of the present disclosure,} _{[100] Fig. 8 shows a breast implant system according to a eighth embodiment of the present disclosure,} _{[101] Fig. 9 shows a breast implant system according to a ninth embodiment of the present disclosure,} _{[102] Figs. 10A and 10B show a breast implant system according to a tenth embodiment of the present disclosure,} _{[103] Figs. 11A to 11D show a breast implant system according to a eleventh embodiment of the present disclosure,} _{[104] Figs. 12A and 12B show a breast implant system according to a twelfth embodiment of the present disclosure, which is a variant of} the embodiment shown in Figs.10A to 10D, _{[105] Figs. 13A and 13B show a breast implant system according to a thirteenth embodiment of the present disclosure, which is another} variant of the embodiment shown in Figs.10A to 10D, _{[106] Figs. 14A to 14D show a breast implant system according to a fourteenth embodiment of the present disclosure,} _{[107] Figs 15A and 15B show a breast implant system according to a fifteenth embodiment of the present disclosure,} _{[108] Fig. 16 shows a breast implant system according to a sixteenth embodiment of the present disclosure,} _{[109] Fig. 17 shows a breast implant system according to a seventeenth embodiment of the present disclosure,} _{[110] Fig. 18 shows, schematically, an embodiment of an inchworm motor,} _{[111] Fig. 19 illustrates, schematically, an operation cycle of a piezoelectric inchworm motor,} _{[112] Fig. 20 shows, schematically, an embodiment of a piezoelectric inertial motor,} _{[113] Fig. 21 shows, schematically, an embodiment of a piezoelectric walk-drive motor,} _{[114] Fig. 22 illustrates, schematically, an operation cycle of a piezoelectric walk-drive motor,} _{[115] Fig. 23 shows, schematically, a Traveling Wave Ultrasonic Motor (TWUSM),} _{[116] Fig. 24 shows, schematically, an embodiment of a Standing Wave Ultrasonic Motor (SWUSM),} _{[117] Fig. 25 shows, schematically, an embodiment of a linear ultrasonic motor,} _{[118] Figs. 26A to 26C show, schematically, an embodiment of a piezoelectric pump,} _{[119] Fig. 27 shows, schematically, an embodiment of a piezoelectric pump in which a diaphragm comprises bellows,} _{[120] Fig. 28 shows, schematically, an embodiment of a piezoelectric pump in which a chamber is configured to be connected to a} pressure adapter, _{[121] Figs. 29A and 29B show, schematically, an embodiment of a ball valve,} _{[122] Figs. 30A and 30B show, schematically, an embodiment of a piezoelectric pump wherein the inlet and outlet comprise static} elements acting as nozzles or diffusers, _{[123] Fig.31 shows, schematically, an embodiment of a piezoelectric pump configured to be operated in a double mode,} _{[124] Fig.32 shows, schematically, an embodiment of a piezoelectric pump comprising at least two portions connected in series,} _{[125] Fig.33 shows, schematically, an embodiment of a piezoelectric pump comprising at least two portions connected in parallel,} _{[126] Fig.34 shows, schematically, an embodiment of a piezoelectric pumping system,} _{[127] Figs. 35A and 35B show a breast implant according to an eighteenth embodiment of the present disclosure,} _{[128] Figs. 36A to 36C show a breast implant system according to a nineteenth embodiment of the present disclosure,} _{[129] Figs. 37A and 37B show a breast implant according to a twentieth embodiment of the present disclosure,} _{[130] Figs. 38A and 38B show a breast implant according to a twenty-first embodiment of the present disclosure,} _{[131] Figs. 39A to 39C show a breast implant to a twenty-second embodiment of the present disclosure,} _{[132] Fig. 40 shows an element for a breast implant according to a twenty-third embodiment of the present disclosure, and} _{[133] Fig. 41 shows an element for a breast implant according to a twenty-fourth embodiment of the present disclosure.} DETAILED DESCRIPTION _{[134] Figs. 1A and 1B show a breast implant system of a first embodiment of the present disclosure in accordance with the first aspect} _{of the present disclosure. More specifically, a cross-sectional view of a breast implant 10 is shown. The breast implant 10 comprises a first} _{fluid chamber 1 which is fixedly connected to a frame 20. The frame 20 is supposed to be implanted next to the patient’s thorax and provides} stability to the breast implant 10. An outer layer 4 of a soft material can optionally be provided. The layer 4 may be formed by a liquid or gel- type silicone or by a foam or by a combination thereof. A main function of the outer layer 4 is to level out irregularities of the first fluid chamber 1 and, more importantly, to form a barrier between the first fluid chamber 1, which is flexible and stretchable, and any fibrosis that _{might form on the outside of the breast implant 10. A second fluid chamber 2 is provided remote from the breast implant 10. By transferring} fluid from the second fluid chamber 2 into the first fluid chamber 1 of the breast implant 10, the look and feel of the breast implant 10 can be _{changed from flaccid to sturdy, as shown in Fig. 1A, whereas re-transfer of the fluid back into the second fluid chamber 2 will change the} shape of the breast implant 10 from sturdy to flaccid. _{[135] The first and second fluid chambers 1 and 2 are connected by a conduit 19 which includes a flow control device 24. In the embodiment} _{shown, the flow control device 24 comprises a throttle arranged in parallel to a check valve. The check valve permits free transfer of fluid} from the second fluid chamber 2 to the first fluid chamber 1 and prevents re-transfer of the fluid through the check valve. However, re- transfer of the fluid from the first fluid chamber 1 to the second fluid chamber 2 is permitted through the throttle so that such re-transfer _{occurs automatically. Since the re-transfer is throttled, the fluid does not flow back immediately but slowly over time. In an advanced} embodiment (not shown), the throttle may be adjustable so as to influence the time span of the fluid reflow. _{[136] Importantly, at least a part of the wall of the first fluid chamber 1 and/or the outer layer 4 is elastic and acts as an energy storage.} That is, when the fluid is transferred from the second fluid chamber 2 into the first fluid chamber 1, the elastic wall or outer layer 4 stretches _{and, thus, is loaded with energy which is automatically released once a force F causing the fluid to flow from the second fluid chamber 2 to} the first fluid chamber 1 is reduced. For instance, the second fluid chamber 2 may be implanted subcutaneously and the force F may be a pressing force of the patient applied on the patient’s skin above the second fluid chamber 2. As stated, the release of the energy stored in the _{outer layer 4 and/or wall of the first fluid chamber 1 causes fluid from the first fluid chamber 1 to automatically flow back into the second} fluid chamber 2. _{[137] Figs. 2A and 2B show a second embodiment of the present disclosure, according to the second aspect of the present disclosure.} Here, the wall of the first fluid chamber 1 or the outer layer 4 provided thereon is not elastic and, thus, does not store any energy when fluid is transferred from the second fluid chamber 2 to the first fluid chamber 1. Rather, a resilient element 25 is provided to expand the second fluid chamber 2 so that it automatically withdraws fluid from the first fluid chamber 1 when the force F, by which the fluid is urged from the _{second fluid chamber 2 into the first fluid chamber 1, is released. In the embodiment shown, the resilient element 25 is a spring, but any other} means causing the second fluid chamber 2 to expand may likewise be employed. Of course, the wall of the first fluid chamber 1 and/or outer layer 4 may be elastic, as in the first embodiment described above, so as to support the fluid-drawing function of the resilient element 25 _{[138] Figs. 3A and 3B show a third embodiment of the present disclosure, according to the second aspect of the present disclosure.} Here, the flow control device 24 comprises a switch. The switch is illustrated as a manually operable. The manual switch may be a purely _{mechanical switch, more specifically a hydraulic switch, as will be described in more detail further below. But the switch may likewise be an} _{electrically operable switch. By means of the switch, the flow control device can be switched between a first state, shown in Fig. 3A, in which} the flow control device 24 permits free transfer of fluid from the second fluid chamber 2 to the first fluid chamber 1, i.e. in a first direction as _{indicated by an arrow in Fig.3A, while preventing transfer of fluid in a second direction opposite to the first direction. Thus, in the first state} of the flow control device 24, fluid can only flow from the second fluid chamber 2 to the first fluid chamber 1. Upon actuation of the switch, the flow control device 24 assumes a second state, shown in Fig.3B, in which the flow control device 24 permits re-transfer of the previously transferred fluid from the first fluid chamber 1 in the second direction back into the second fluid chamber 2. Unlike in the first and second embodiments discussed above, such fluid reflow through the flow control device 24 is unthrottled. Accordingly, the patient may decide the _{point in time to initiate the automatic re-transfer of the fluid from the first fluid chamber 1 back to the second fluid chamber 2 by switching} _{the flow control device 24 from its first state to its second state. Then, the fluid reflow is automatic, meaning that the patient does not have} to take any further action. Once actuated, the flow control device 24 simply remains in the second state which is shown in Fig.3B. _{[139] For the next cycle, i.e. when the patient desires to expand the breast implant 10 again, the pressure which is built up in the conduit} 19 upon transfer of the fluid from the second fluid chamber 2 to the first fluid chamber 1 is applied to the flow control device 24 such that the flow control device 24 switches back from the second state to the first state, as indicated by dotted lines in Fig.3A. The flow control device 24 remains in the first state until it is actively switched into the second state. However, instead of an unthrottled reflow of the fluid from the first fluid chamber 1 to the second fluid chamber 2, a throttle similar to the first and second embodiments described above may be provided _{in the flow control device 24 so as to throttle the reflow, as is shown Fig.4A and 4B.} _{[140] Figs.5A to 5C show a fifth embodiment of the present disclosure, according to the first aspect of the present disclosure. It differs} _{from the first embodiment described above in relation to Figs. 1A and 1B only in that a servo system is provided for actuation of the second} fluid chamber 2. Here, the flow control device 24 makes part of the servo system, but it may alternatively be placed between the first and _{second fluid chambers 1 and 2, as in the previous embodiments. Furthermore, the servo system may be provided likewise in the embodiments} 2 to 4 described above. _{[141] More specifically, the second fluid chamber 2 has the form of a bellows and forms a first sub-chamber R’ of the servo system. A} _{second sub-chamber R” cooperated with a first sub-chamber R’ such that filling of the second sub-chamber R” with a fluid from a third sub-} chamber R”’ will cause the first sub-chamber R’ to be compressed, and vice versa. Thus, when fluid is pumped from the third sub-chamber R”’ into the second sub-chamber R”, the length and, thus, the volume of the first sub-chamber R’ decreases. The situation is such, however, _{that the volume change in the second sub-chamber R”, which is also in the form of a bellows, is less than the volume change in the first sub-} chamber R’. _{[142] The way of transferring fluid from the first sub-chamber R’ into the first fluid chamber 1 of the breast implant 10 will now be} explained. That is, the regular state of the breast implant 10 may be sturdy, as shown in Fig.5A. When the third reservoir R”’, which may be _{implanted subcutaneously, is compressed, e.g. by an external force F applied by the patient through the patient’s skin, fluid flows through the} check valve in the flow control device 24 into the second sub-chamber R”, thereby compressing the first sub-chamber R’ against the force of the resilient element 25 so that fluid flows from the first sub-chamber R’ into the breast implant 10. Once the compression force F is released, the energy stored in the compressed resilient element 25 causes the first sub-chamber R’ to expand, thereby drawing fluid from the first fluid chamber 1 of the breast implant 10 back into the first sub-chamber R’, which action is automatic. However, the reflow of the fluid is _{throttled by the throttle in the flow control device 24. Therefore, the shape of the breast implant 10 will change from sturdy to flaccid, as} shown in Fig.5C. _{[143] Figs. 6A to 6C show a sixth embodiment of the present disclosure, according to the second aspect of the present disclosure. Here,} _{the flow control device 24 basically corresponds to the flow control device in the third and fourth embodiments discussed above in relation} to Figs.3A, 3B and Figs.4A, 4B, respectively. More specifically, however, here the manual-type switch is illustrated as a hydraulic switch. That is, a pressure chamber 23 is subcutaneously arranged for being manually compressed through the skin by the patient, and a hydraulic line _{applies such pressure to the flow control device 24 so as to switch the flow control device 24 from the second state to the first state, as} described in more detail above in relation to Figs.3A, 3B. In particular, the automatic reflow of fluid, as indicated in Fig.6C by an arrow in the first fluid chamber 1, is unthrottled. _{[144] Figs. 7A to 7C show a seventh embodiment of the present disclosure, according to the second aspect of the present disclosure. It} _{differs from the sixth embodiment only in that the flow control device 24 includes a throttle so that the automatic reflow of fluid, as shown in} Fig.7C, is throttled, similar to the fourth embodiment described above in relation to Figs.4A, 4B. _{[145] Figs. 8 and 9 show an eighth and a ninth embodiment of the present disclosure, according to the first and second aspects of the} present disclosure, respectively, which embodiments are somewhat more complex. The basic structure of these breast implant systems corresponds to the structure described above in relation to Figs.2A, 2B and Figs.3A, 3B, respectively, except that there is more than one _{first fluid chamber 1 provided in the breast implant 10. What is important in the eighth and ninth embodiments of Figs. 8 and 9 is the pump P} _{which is driven by a motor M and arranged to pump fluid between the first and second fluid chambers 1 and 2. The fluid chamber 2 may be} implanted anywhere remote in the patient’s body, such as in the abdominal cavity _{[146] The motor M is energized with wirelessly transmitted energy. For this purpose, the breast implant system comprises an energy} _{transmitter 29 outside the patient’s body and an energy receiver 30 inside the patient’s body, preferably subcutaneously implanted above the} patient’s sternum, to transform the wireless energy into electric energy. While it is possible to make use of a motor M adapted to directly _{transform the wirelessly transmitted energy into kinetic energy or, alternatively, to transform the wirelessly transmitted energy into electric} _{energy by means of an energy transforming device so as to drive the motor M directly as the energy transforming device transforms the} _{wireless energy into the electric energy, the specific embodiments shown in Figs. 8 and 9 first store the transmitted electric energy in an} _{energy storage E before it is supplied to the motor M. Of course, it is also possible that a part of the transmitted energy is directly used by} the motor while another part of the transmitted energy is stored in the energy storage E. The energy storage E may include an accumulator such as a rechargeable battery and/or a capacitor. It is less convenient, but possible, to implant a regular battery as the energy storage _{means E. But a regular battery may be used as the energy source to provide the wireless energy to be transmitted from outside the patient’s} body _{[147] The breast implant system shown in the specific embodiment of Figs 8 and 9 further includes a control unit. The control unit here} comprises a first part C1 to be used by the patient from outside the patient’s body and a second part C2 to be implanted inside the patient’s body. Data can thus be transmitted wirelessly between the first and second parts C1, C2 of the control unit. In addition or alternatively, the implantable second part C2 of the control unit may be programmable via the first part of the control unit. Preferably, the data are transmitted between the first and second parts C1, C2 of the control unit in the same manner as energy is transmitted, such as via the transmitter 29 and _{receiver 29} _{[148] The external part C1 of the control unit may also be replaced with a simple manually operable switch for activating the implantable} control unit C2. Such switch is then arranged for subcutaneous implantation so as to be operable from outside the patient’s body. It is also _{possible to combine such switch with an external part C1 of the control unit.} _{[149] Furthermore, feedback information may be sent between the implanted part C2 and the external part C1 of the control unit. Such} feedback information may include information related to the energy to be stored in the energy storage E. The control unit can make use of such feedback information for adjusting the amount of wireless energy transmitted by the energy transmitter 29. The feedback information _{may be related to an energy balance, which may be defined either as the balance between an amount of wireless energy received inside the} human body and an amount of energy consumed by the motor and pump, or as the balance between a rate of wireless energy received inside the human body and a rate of energy consumed by the motor and pump. _{[150] Furthermore, the embodiments shown in Figs.8 and 9 include an injection port 31 implanted under the patient’s skin. Fluid can be added} to or removed from the breast implant system by means of a regular syringe if need arises. While only one injection port 31 is shown, two or more injection ports may be provided in order to allow for individual adjustment of the fluid volume in the particular fluid chambers. _{[151] The flow control device 24 shown in Fig. 8 may be replaced with the flow control device shown in Figs. 4A, 4B, which includes a throttle.} Likewise, instead of the resilient element 25, or in addition thereto, the outer wall of the first fluid chamber 1 may be elastic, as described in _{relation to the first embodiment shown in Figs. 1A, 1B.} _{[152] Figs. 10A and 10B show a tenth embodiment of the present disclosure, according to the first aspect of the present disclosure. Here, a} _{rigid back wall 3 is provided to which the first fluid chamber 1 and the second fluid chamber 2 are fixedly mounted. By means of the piston 8} _{which is arranged in a cylinder 5 integrated in the back wall 3, fluid can be exchanged between the first and second fluid chambers 1, 2. The} _{first fluid chamber 1 together with the back wall 3 defines an enclosed space forming a third fluid chamber 14. The third fluid chamber 14} comprises a compressible medium, such as a gas or a foam in which the gas is contained. Fluid is exchanged only between the first and second chambers 1, 2, whereas the third fluid chamber 14 is completely isolated, being separated from the first fluid chamber by a separating wall 15 _{and from the second fluid chamber 2 by separating wall 16. Both separating walls 15, 16 are flexible and at least the separating wall 15 should} be non-stretchable. _{[153] When fluid is pumped from the first fluid chamber 1 into the second fluid chamber 2, the volumes of the fluid chambers 1 and 2 will} change accordingly, as is shown in Fig.10B. The outer wall of the first fluid chamber 1 is elastic so as to adapt to the reduced volume, but may also be non-elastic, provided that it is sufficiently flexible to conform to the changed volume. Again, an outer layer 4, as shown in Figs.3A, 3B, can be provided here (and in all embodiments described herein). Due to the fact that the separating wall 15 is non-stretchable, the increased _{volume of the second fluid chamber 2 causes the pressure in the third fluid chamber 14 to rise from an initial pressure P1 to a raised pressure} P2. Altogether, not only has the shape of the breast implant 10 changed, but the volume has also changed. However, the mass and, thus, the weight of the breast implant has not changed at all. _{[154] The increased pressure P2 constitutes an energy storage which urges the piston 8 in the reverse direction. Such reverse} movement is slowed down by friction acting on the piston 8, which friction counteracts the release of the pressure energy stored in the compressible fluid contained in the third fluid chamber 14. As a result, the shape of the breast implant will assume its original shape again _{slowly over time, depending on the amount of friction acting on the piston 8. The amount of friction may be adjusted once and forever during} the manufacture of the breast implant 10 or prior to its implantation, or it may be adjustable by the patient (not shown). _{[155] One way of providing friction to the piston 8 is illustrated in Figs.10A and 10B. Here, the piston 8 has a piston rod 9 connecting the} _{piston 8 to a secondary piston 8’ in a secondary cylinder 5’ which contains a secondary fluid. The secondary cylinder 8’ includes a one-way} _{throttle valve 6 which allows free flow of the secondary fluid through the secondary piston 8’ in one direction and, thus, free movement of the} _{cylinder 8 in that same direction, and throttled flow in parallel thereto. Accordingly, reflow of the secondary fluid through the secondary} cylinder 8’ is throttled. That is, the friction acting against the movement of the cylinder 8 when fluid is urged to flow back from the second fluid chamber 2 to the first fluid chamber 1 is generated by the fluid friction in the throttle of the one-way throttle valve 6 of the secondary piston 8’ when the secondary fluid flows therethrough. An advantage of this arrangement is that the fluid friction acts only in one direction of piston movement, i.e. during the automatic reflow, whereas no friction needs to be overcome when the piston 8 is moved in the opposite direction. _{[156] Figs. 11A to 11D show an eleventh embodiment of the present disclosure according to the second aspect of the present disclosure,} i.e. it comprises a switch in order to switch the flow control device 24 between a first state and a second state. This embodiment substantially corresponds to the embodiment shown in Figs.6A to 6C except that the first fluid chamber 1 contains a number of elements 21, 22, of which a _{first element 21 is displaceably arranged within the first fluid chamber 1, whereas a second element 22 is fixedly mounted to the rigid back} wall 3 of the breast implant 10. The elements 21 and 22 may be cushion-like or pad-like. In particular, they may have a variable fluid content similar to the first and second fluid chambers 1 and 2 in the above discussed embodiments (see also hereinafter Figs.12A, 12B and 13A, 13B). However, it is likewise possible that the elements 21, 22 have a constant volume and are, e.g., filled with granular material or a gel material. In this particular embodiment, the first fluid chamber 1 is formed by the rigid back wall 3 and the outer layer 4. The first fluid chamber may _{contain more than the first and second elements 21 and 22, and all elements may be displaceably contained therein.} _{[157] In this eleventh embodiment, the second fluid chamber 2 forms a reservoir R’ which accommodates a lubricating fluid. While the} breast implant system shown here includes a servo system for supplying the lubricating fluid from the lubricating fluid reservoir into the fluid _{chamber 1, such servo system may be dispensed with. In any case, the servo system shown in Figs. 11A to 11D functions in the same way as in} _{the embodiment described above in relation to Figs.6A to 6C.} _{[158] Fig. 11A shows the breast implant 10 in its regular state, e.g. a relatively flaccid state. When the patient compresses the third sub-} chamber R”’ of the lubricating reservoir (see the arrow F in Fig.11B), fluid will ultimately flow from the first sub-chamber R’ into the first fluid chamber 1 and between the first and second elements 21 and 22 contained therein as well as between the outer layer 4 and the first and _{second elements 21, 22. Such lubrication reduces surface friction between the elements 21, 22 and the outer layer 4, respectively, so that the} _{patient can easily reshape the breast implant 10 manually from outside the breast and reach a shape, e.g., as shown in Fig. 11C. During such} reshaping process, the flow control device 24 remains in its first state, i.e. the state in which any reflow back from the first fluid chamber 1 to the sub-chamber R’ of the lubricating reservoir is prevented. After the reshaping process is completed to the satisfaction of the patient, _{the patient may compress the subcutaneously arranged pressure chamber 23 (or actuate any other means, not shown) in order to switch} _{the flow control device 24 to its second state, the second state permitting unrestricted reflow of the lubricating fluid from the first fluid} chamber 1 back into the sub-chamber R’ of the lubricating reservoir, as shown in Fig.11D. Alternatively, the reflow may be throttled in the same _{way as in the flow control devices 24 referred to above in the fourth and seventh embodiments shown in Figs. 4A, 4B and 7A to 7C, respectively.} _{[159] Figs. 12A and 12B as well as Figs. 13A and 13B show a twelfth and a thirteenth embodiment of the present disclosure, respectively,} according to the first aspect of the present disclosure. The structure may basically be the same as in the previous, eleventh embodiment, but _{the lubricating reservoir is illustrated in Figs. 12A, 12B and 13A, 13B in a simplified manner by the second fluid reservoir 2. The twelfth and} thirteenth embodiment differ from the eleventh embodiment in that fluid can be exchanged between the elements 21 and 22, e.g. by a piston- _{cylinder-arrangement 8, 5, as shown in Figs. 12A, 12B. The piston-cylinder-arrangement 8, 5 is used to influence the shape of the breast} _{implant 10 without changing its volume. Alternatively, as shown in Figs.13A, 13B, some or all of the elements 21, 22 may be individually connected} _{to separate reservoirs R1 and R2, respectively, so as to change their respective fluid contents individually. This way, not only the shape but} also the volume of the breast implant 10 can be influenced. _{[160] Figs. 13A to 13D show a thirteenth embodiment of the present disclosure, according to the second aspect of the present invention,} _{namely a breast implant system which comprises a flow control device 24 that can be switched between a first and a second stage. Thus, the} overall structure is similar to the fourteenth embodiment of Figs.11A to 11D with the sole difference that the first fluid chamber 1 contains (only) a large number of elements 21 of a first type. The second fluid chamber 2 constitutes a sub-chamber R’ of a lubricating reservoir. The elements 21 may have the form of regular or irregular spheres, and there may be 1000 or more of those spheres contained in the first fluid chamber 1. _{[161] The functionality of the breast implant system of this fourteenth embodiment is the same as in the eleventh embodiment discussed} above in relation to Figs.11A to 11D. That is, the regular shape of the breast implant may be flaccid, as shown in Fig.13A. Upon a pressure F applied to the sub-chamber R’’’ from outside the patient’s body, as shown in Fig.13B, lubricating fluid flows from the sub-chamber R’ into the _{first fluid chamber 1 and further between the spheres 21. Then, the patient can easily reshape the breast implant 21, e.g. to a shape as shown} _{in Fig. 13C. Thereafter, the patient switches the flow control device 24 from the first state into the second state, e. g. by compressing a} _{hydraulic actuator 23 subcutaneously implanted under the patient's skin. This way, the lubricating fluid is automatically withdrawn from the} first fluid chamber 1 due to the energy stored in the resilient element 25 which expands the sub-chamber R’. _{[162] Figs. 15A and 15B show a fifteenth embodiment of the present disclosure according to the third aspect of the present disclosure.} This embodiment basically corresponds to the ninth embodiment discussed above in relation to Fig.9. The main difference is that the energy _{receiver 30 is configured for implantation within the patient's body above the patient's sternum S, as shown in Fig. 15B, and that the energy} consuming parts such as the pump P and/or motor M make part of the breast implant 10. More specifically, in the embodiment shown, the _{energy consuming parts are contained in a rigid back wall 3 of the breast implant 10 which is configured for being placed adjacent the patient's} _{thorax. Fig. 15A shows only the principle of such an arrangement in the back wall 3. In addition to the pump P and motor M, the energy storage} E as well as an optional energy transforming device (as discussed in relation to Fig.9, not shown here) may likewise be integrated in the rigid _{back wall 3. The same applies to the flow control device 24, which may be electronically switchable as indicated in Fig. 15A. The flow control} _{device 24 is configured to bridge the pump P so as to allow back flow from the first fluid chamber 1 in the breast implant 10 to the remotely} implanted second fluid chamber 2 in order to permit automatic reflow in conjunction with the resilient element 25. However, the flow control device 24 and resilient element 25 can be dispensed with if automatic reflow is not desired, in which case the re-transfer of fluid from the first fluid camber 1 to the second fluid chamber 2 may be realised by means of the pump P. Furthermore, instead of the pump P, a piston- cylinder-arrangement may be provided similar to the twelfth embodiment discussed above in relation to Figs.12A, 12B and tenth embodiment _{discussed above in relation to Figs. 10A, 10B, respectively, and the piston may be driven by a motor M integrated in the breast implant 10, in} particular in the back wall 3 of the breast implant 10. _{[163] Preferably, the pump P and/or motor M is a piezoelectric pump, as will be described in further detail below in relation to the} embodiments shown in Figs.18 through 34 in context with the eighth aspect according to the present disclosure. _{[164] The principle of integrating a pump P and/or motor M in the breast implant 10, in particular in a rigid back wall 3 thereof, according} to the third aspect of the present disclosure is further shown in Figs.16 and 17 which show a sixteenth and seventeenth embodiment of the present disclosure, respectively. In these embodiments, the second fluid chamber 2 forms a lubricating reservoir for the first fluid chamber _{1, and a pump P is provided for transferring the fluid back and forth between the first and second fluid chambers 1 and 2. In addition, in the} sixteenth embodiment shown in Fig.16, fluid can be exchanged between the first element 21 and second element 22 by means of the piston- cylinder-arrangement 8, 5 which is driven by a motor M. Both, the pump P and the motor M may be provided with an automatic reflow as _{explained above in relation to the first and second aspect of the present disclosure. The seventeenth embodiment shown in Fig. 17 differs from} the sixteenth embodiment in that the fluid is not exchanged between the first and second elements 21, 22, but rather each of the first and second elements 21, 22 are provided with a separate fluid reservoir R21 and R22, respectively, which is configured for remote implantation within the patient's body. Thus, the sixteenth and seventeenth embodiments basically correspond to the embodiments described above in relation to Figs.12A, 12B and 13A, 13B, respectively. _{[165] Each of the motor M and pump P in the embodiments shown in Figs. 16 and 17, respectively, is provided with an individual energy} receiver 30 for implantation above the patient's sternum S underneath the patient's skin. The longitudinal extension of the sternum S allows _{for implanting the energy receivers 30 side by side so that they can be individually approached by the patient with an energy transmitter 29,} _{depending on the action which the patient wishes to perform. Alternatively, the breast implant system may comprise a control device, such} as the control device C1, C2 described in relation to the eighth embodiment shown in Fig.8, in which case the energy receivers 30 may be _{combined into a single energy receiver 30.} _{[166] As mentioned above, according to an eighth aspect of the present disclosure, the breast implant system may comprise one or} _{more piezoelectric motors and/or one or more piezoelectric pumps. More specifically, the breast implant system may comprise a plurality} _{of chambers, including the first fluid chamber 1 and a second fluid chamber 2 which are adapted for implantation in the human body with the} first fluid chamber 1 forming part of the breast implant 10, wherein the first and second fluid chambers 1 and 2 are interconnected when implanted for fluid to be transferred between the first and second fluid chambers 1 and 2 so as to change their respective fluid content. _{Thus, any one of the motor or motors and pump or pumps for driving certain parts of the breast implant system of any one of the first to} _{fifteenth embodiments of the present disclosure are preferably piezoelectric. This will be further explained in relation to Figs.18. to 34.} _{[167] The piezoelectric effect is a property of certain solid materials to generate an electrical voltage in response to an applied} mechanical stress (so-called direct piezoelectric effect) and to deform elastically in response to an applied electrical voltage (so-called _{inverse piezoelectric effect). The piezoelectric effect is a reversible process, meaning that materials exhibiting the direct piezoelectric} effect also exhibit the inverse piezoelectric effect. _{[168] Materials exhibiting the piezoelectric effect are denoted as piezoelectric materials. Examples of piezoelectric materials comprise:} crystalline materials, such as lithium niobate, lithium tantalate and quartz; ceramics, such as lead zirconate titanate, potassium niobate and _{barium titanate; polymers, such as polyvinylidene fluoride.} _{[169] Piezoelectric coefficients are a fundamental property of piezoelectric materials. A given piezoelectric material is characterized} by a set of piezoelectric coefficients, wherein a piezoelectric coefficient is a measure of the relationship between the applied mechanical stress along a first direction and the generated electric charge along a second direction. Piezoelectric coefficients are usually expressed in units of picocoulombs per newton (pC/N). The value of piezoelectric coefficients may strongly vary depending on the piezoelectric material and piezoelectric coefficient being considered. For example, the ^_^^ piezoelectric coefficient is commonly reported for piezoelectric materials and quantifies the electric charge generated along a given direction in response to the mechanical stress applied along the same direction. _{[170] A piezoelectric motor or piezo motor is a type of electric motor that uses the inverse piezoelectric effect to generate mechanical} motion, typically linear or rotatory motion. Piezo motors are often used in applications where precise positioning and fine control of movement are required. Piezo motors have the advantage of providing high motion accuracy, being possible to miniaturize and being relatively immune to interference, such as electromagnetic interference. Piezoelectric motors can also be manufactured without magnetic and/or metallic parts, and instead be manufactured from ceramics or certain composites. This feature is particularly advantageous in _{medical and biotechnology applications with strong magnetic fields. Piezoelectric motors can thus be made MRI-safe, meaning that the} patient can undergo Magnetic Resonance Imaging (MRI) while having the piezo motor implanted. MRI is a medical imaging technique used to form pictures of the anatomy and the physiological processes of the body using strong magnetic fields. Conventional implantable electromagnetic motors prevent the use of MRI as the strong magnetic field risks damaging both the patient and the implant. _{[171] Also, compared to classical electromagnetic motors, piezo motors may have a simpler structure and smaller footprint. Piezo} motors may offer improved positioning accuracy and simpler design, as linear motion may be obtained directly, without the need of mechanical coupling elements otherwise required to convert the rotary motion of classical electromagnetic motors to linear motion. The fact that linear motion can be obtained directly may improve the positioning accuracy. _{[172] An additional advantage of piezoelectric motors is that they usually feature higher energy-efficiency and less power consumption} compared to conventional electromagnetic motors. _{[173] As discussed in more detail below, inchworm motors, inertial motors, walk-drive motors and ultrasonic motors are four suitable} types of piezoelectric motors. _{[174] Fig. 18 shows an embodiment of an inchworm motor MO configured to generate linear motion. The inchworm motor MO comprises} a first lateral piezoelectric actuator 801a and second lateral piezoelectric actuator 801b. The first lateral piezoelectric actuator 801a is _{laterally connected to a first clutching actuator 802a’ and a second clutching actuator 802a’’. The second lateral piezoelectric actuator} _{801b is laterally connected to a third clutching actuator 802b’ and a fourth clutching actuator 802b’’. The inchworm motor MO is configured} _{to impart a linear motion to a movable member 805. The movable member 805 is configured to be attached to the load or mechanism to be} moved, for instance to a signal emitter (1) or a relevant part thereof. _{[175] Fig. 19 illustrates an operation cycle of the piezoelectric inchworm motor MO wherein the movable member 805 is linearly moved} in a direction to the right in the illustration by sequentially controlling the first and second piezoelectric actuators 801a, 801b and the clutching actuators 802a’, 802a’’, 802b’, 802b’’. In an initial relaxation state, the movable member 805 is detached from all the clutching _{actuators 802a’, 802a’’, 802b’, 802b’’. The inchworm motor MO is subsequently brought into an initialization state by electrically activating} _{the second and fourth clutching actuators 802a’’, 802b’’. As a result, the clutching actuators 802a’’, 802b’’ extend and clutch the movable} member 805. _{[176] In step 1, the first and second lateral actuators 801a, 801b extend in response to an applied electrical voltage. As a result, the} _{movable member 805 undergoes a first linear displacement with a distance equal to half the distance of the extension of the lateral} actuators 801a, 801b. _{[177] In step 2, the first and third clutching actuators 802a’, 802b’ are electrically activated. As a result, the first and third clutching} _{actuators 802a’, 802b’ extend and clutch the movable member 805.} _{[178] In step 3, the electrical voltage applied to the third and fourth clutching actuators 802a’’, 802b’’ is decreased as compared to the} initialization state. As a result, the third and fourth clutching actuators 802a’’, 802b’’ detach from the movable member 805. _{[179] In step 4, the electrical voltage applied to the first and second lateral actuators 801a, 801b is decreased as compared to step 1.} As a result, the first and second lateral actuators 801a, 801b contract and the movable member 805 undergoes a second linear displacement with a distance equal to half the distance of the contraction of the lateral actuators 801a, 801b. _{[180] In step 5, the second and fourth clutching actuators 802a’’, 802b’’ are electrically activated such that they extend and clutch the} movable member 805. _{[181] In step 6, the electrical voltage applied to the first and second clutching actuators 802a’, 802b’ is decreased as compared to} step 2. As a result, the first and second clutching actuators 802a’, 802b’ contract and detach from the movable member 805. _{[182] The steps from 1 to 6 may be repeated a number of times in the sequence illustrated above in order to move the movable} member 805 by a desired distance. _{[183] This configuration of an inchworm piezoelectric motor MO creating a linear motion can be used to generate the linear motion of} the infusion needle 11. Where the infusion needle 11 is moved in two lateral directions, such as sideways and upward/downward, two _{piezoelectric motors may be provided. In the embodiment shown in Fig. 19, the inchworm motor is configured to generate a linear motion at} _{a speed in the range of 1 mm/s to 10 mm/s, a stroke length of up to 5 mm and a force in the range of 2 N – 30 N.} _{[184] In another embodiment, the movable member 805 may be replaced with a rotary module (not shown) such that the inchworm} motor can be used to generate rotary motion of the infusion needle 11 in those embodiments where the needle 11 is rotatable. An inchworm _{motor configured to generate rotary motion may have a rotational speed in the range of 0.5 mrad/s to about 70 mrad/s and a torque} ranging from about 100 Nmm to about 900 Nmm. _{[185] Fig. 20 illustrates an embodiment of a piezoelectric inertial motor MO configured to generate linear motion. The motor MO} comprises a movable member 805, a piezoelectric actuator 801, a recoiling member 804 and a base 806. The movable member 805 is attached to the piezoelectric actuator 801. The piezoelectric actuator 801 is attached to the recoiling member 804. The movable member 805 is in contact with the base 806. The movable member 805 is configured to be attached to the load or mechanism to be moved, for instance to a signal emitter (1) or a relevant part thereof. _{[186] An operation mode of the piezoelectric inertial motor MO described in Fig.20 comprises two steps. In step 1, the piezoelectric} _{actuator 801 slowly elongates in response to an applied voltage. Due to the static friction between the movable member 805 and the base} 806, the movable member 805 does not move. In step 2, the piezoelectric actuator 801 rapidly contracts in response to a change in the _{applied voltage. As a result of the recoil produced by the recoiling member 804, the movable member 805 moves by a distance Δx to the left} in the illustration of Fig.20. By reversing the operation cycle, the piezoelectric inertial motor MO generates motion in the opposite direction. _{[187] In the embodiment shown in Fig. 20, the piezoelectric inertial motor MO is configured to generate linear motion and may feature a} _{speed in the range of 1 mm/s – 10 mm/s, a stroke length of up to 5 mm and a force in the range of 2 N – 30 N.} _{[188] This configuration of a piezoelectric inertial motor MO creating a linear motion can be used to generate the linear motion of the} infusion needle 11. Where the infusion needle 11 is moved in two lateral directions, such as sideways and upward/downward, two piezoelectric motors may be provided. _{[189] In alternative embodiments of piezoelectric inertial motors (not shown), the movable member 805 may be replaced with a rotary} module such that the piezoelectric inertial motor is configured to generate rotary motion. Such a piezoelectric inertial motor creating a rotary movement can be used to generate rotary motion of the infusion needle 11 in those embodiments where the needle 11 is rotatable. _{Piezoelectric inertial motors configured to generate rotary motion may have a rotational speed in the range of 1 mrad/s – 100 mrad/s and} _{a torque in the range of 100 Nmm – 900 Nmm.} _{[190] Yet another design of a piezoelectric motor suitable for use in the implantable medical device described herein is the walk-drive} motor. Walk-drive motors take their name from the fact that their working principle essentially resembles a walk. Linear motion is achieved through the coordinated and sequential action of a number of piezoelectric actuators acting as legs. _{[191] Fig. 21 shows an embodiment of a piezoelectric walk-drive motor MO. The piezoelectric walk-drive motor MO comprises a number} _{of piezoelectric actuators 801a – 801d attached to a supporting member 800. The piezoelectric actuators 801a – 801d may be divided into a} first set 801a, 801c and a second set 801b, 801d. The first and second set 801a, 801c and 801b, 801d of piezoelectric actuators may be controlled independently. The piezoelectric walk-drive motor MO is configured to impart a linear motion to a movable member 805 by _{sequentially controlling the piezoelectric actuators 801a – 801d. The movable member 805 is configured to be attached to the load or} mechanism to be moved, for instance to a signal emitter (1) or a relevant part thereof. _{[192] A piezoelectric walk-drive motor 805 may be operated in various operation modes, each offering specific advantages in terms of} performance. _{[193] Fig. 22 illustrates an operation cycle of a piezoelectric walk-drive motor MO according to one embodiment. In this embodiment,} the first set of piezoelectric actuators 801a, 801c is controlled by a first electrical voltage ^_^. The second set of piezoelectric actuators 801b, 801d is controlled by a second electrical voltage ^_^. The cycle comprises a number of steps. _{[194] In step 1, in response to a change in ^^, the first set of piezoelectric actuators 801a, 801c stretch and make contact with the} movable member 805. When in contact, the first set of piezoelectric actuators 801a, 801c are bended sideways in a direction opposite to the motion direction D. Conversely, the second set of piezoelectric actuators 801b, 801d detach from the movable member 805 in response to a change in ^_^. _{[195] In step 2, the first set of piezoelectric actuators 801a, 801c maintain contact with the movable member 805 and bend in the} motion direction D in response to a change in ^_^. The second set of piezoelectric actuators 801b, 801d remain detached from the movable _{member 805. As a result of the friction between the first set of piezoelectric actuators 801a, 801c and the movable member 805, the} movable member 805 is moved in the motion direction D. _{[196] In step 3, in response to a change in ^^, the second set of piezoelectric actuators 801b, 801d stretch and make contact with the} movable member 805. When in contact, the second set of piezoelectric actuators 801b, 801d are bended in a direction opposite to the motion direction D. Conversely, the first set of piezoelectric actuators 801a, 801c detach from the movable member 805 in response to a change in ^_^. _{[197] In step 4, the second set of piezoelectric actuators 801b, 801d maintain contact with the movable member 805 and bend in the} motion direction D in response to a change in ^_^. The first set of piezoelectric actuators 801a, 801c remain detached from the movable member 805. As a result of the friction between the second set of piezoelectric actuators 801b, 801d and the movable member 805, the movable member 805 is moved in the motion direction D. _{[198] The piezoelectric actuators 801a – 801d in Fig.19 and Fig. 20 may be bimorph piezoelectric actuators. A bimorph actuator} comprises at least two piezoelectric layers bonded together and oppositely responding to a given applied voltage. E.g., one layer extends and the other contracts. As a result, the bimorph actuator may stretch and bend. Alternatively, any of the piezoelectric actuators 801a – _{801d in Fig.19 and Fig. 20 may comprise a top part (illustrated as 801a’ in Fig. 19), configured to be attached to the supporting member 800,} and a bottom part (exemplified by illustration as 801a’’ in Fig.19). The top part 801a’ is configured to deform perpendicularly to the motion direction D in response to the voltage applied to the piezoelectric actuator 801a. The bottom part 801a’’ is configured to deform parallelly to the motion direction D in response to the voltage. As a result, the piezoelectric actuator 801a may stretch and bend. _{[199] By reversing the operation cycle, the piezoelectric walk-drive motor MO generates motion in the opposite direction.} _{[200] In the embodiment shown in Figs. 19 and 20, the piezoelectric walk-drive motor MO is configured to generate linear motion at a} _{speed in the range of 1 mm/s to 10 mm/s and a force in the range of 2 N – 30 N. As the maximum stroke is limited by the length of the} _{movable member 805 (also called a runner), there is no set limit for the maximum stroke.} _{[201] This configuration of a piezoelectric walk-drive motor MO creating a linear motion can be used to generate the linear motion of} _{the infusion needle 11. Where the infusion needle 11 is moved in two lateral directions, such as sideways and upward/downward, two} piezoelectric motors may be provided. _{[202] In alternative embodiments of the piezoelectric walk-drive motor (not shown), the movable member 805 may be replaced with a} rotary module such that the piezoelectric walk-drive motor is configured to generate rotary motion. Such a piezoelectric walk-drive motor configured to generate rotary motion can be used to generate rotary motion of the infusion needle 11 in those embodiments where the _{needle 11 is rotatable. Piezoelectric walk-drive motors configured to generate rotary motion may have a rotational speed in the range of 0.5} _{mrad/s to about 70 mrad/s and a torque ranging from about 100 Nmm to about 900 Nmm.} _{[203] An ultrasonic motor is another type of piezoelectric motor. In ultrasonic motors, a first component of the motor, the stator,} _{supports mechanical vibrations in the ultrasonic frequency range – from tens to hundreds of kHz. The stator comprises a number of} piezoelectric actuators. Ultrasonic mechanical vibrations are excited in the stator in response to an electrical voltage applied to the _{piezoelectric actuators. The stator is configured to transfer the ultrasonic vibrations to a second component of the motor, such as a rotor} _{or slider depending on the scheme of operation. Depending on the scheme of operation, various types of motion, such as linear or rotary,} may be imparted to the second component. _{[204] A rotary ultrasonic motor is a piezoelectric ultrasonic motor configured to generate rotary motion. Rotary ultrasonic motors} comprise traveling wave ultrasonic motors (TWUSM) and standing wave ultrasonic motor (SWUSM). In TWUSMs the stator vibrates _{according to a travelling wave pattern. In SWUSMs the stator vibrates according to a standing wave pattern.} _{[205] Fig. 23 shows an embodiment of a TWUSM MO. The TWUSM MO comprises a ring-shaped stator 810 with a top and a bottom} surface. The stator 810 is configured to engage with a ring-shaped rotor 811. The stator 810 comprises a ring-shaped member 810’, a first _{number of piezoelectric actuators 801a and a second number of piezoelectric actuators 801b. The piezoelectric actuators 801a, 801b are} attached to the ring-shaped member 810’. An alternating electrical voltage VA may be applied from a first voltage generator 812a (typically a controller connected to an energy source) to the piezoelectric actuators 801a. An alternating electrical voltage VB, phase-shifted with respect to VA, may be applied from a second voltage generator 812b to the second number of piezoelectric actuators 801b. The ring-shaped member 810’ may comprise a number of teeth 813. The rotor 811 is configured to be attached to the load or mechanism to be moved. _{[206] The first number of piezoelectric actuators 801a deform in response to the voltage VA such that they induce a first vibration} pattern in the stator 810. The second number of piezoelectric actuators 801b deform in response to the voltage VB such that they induce a second vibration pattern in the stator 810. The interference of the first and second vibration pattern excites a travelling wave 814 in the _{stator 810. The travelling wave 814 has a given propagation direction D1, either clock-wise or counter-clockwise. The regions of maximum} _{displacement – so-called antinodes – and regions of no displacement – so-called nodes – of the travelling wave pattern oscillate} transversely with respect to the top and bottom surface of the stator 810, but they also travel circumferentially along the stator 810 perimeter. _{[207] The propagation of the travelling wave 814 makes the stator vibrate accordingly. As a result, the stator 810 imparts a rotatory} _{motion to the rotor 811 in a rotation direction D2, opposite to the travelling wave 814 propagation direction D1. The teeth 813 facilitate the} motion transmission from the stator 810 to the rotor 811 by enhancing the friction between the rotor 811 and the stator 810. _{[208] The frequency and amplitude of the applied electrical voltages may be controlled and adjusted to tune the performance of the} TWUSM MO, including speed, direction and accuracy of motion. _{[209] In contrast to TWUSMs, a standing wave ultrasonic motor (SWUSM) requires only a single alternating electrical voltage to} operate. In response to this applied voltage, the piezoelectric actuators 801a, 801b of the stator 810 make the stator 810 vibrate according to a standing wave pattern. A standing wave is characterized by antinodes and nodes that do not travel in space. As a result, a standing wave does not have a propagation direction. The stator 810 vibrates in a way that antinodes and nodes oscillate transversely with respect to the top and bottom surface of the stator. However, antinodes and nodes do not travel circumferentially along the stator. _{[210] Fig. 24 shows an embodiment of a SWUSM. The SWUSM MO comprises a ring-shaped stator 810 with a top and a bottom surface.} The stator 810 is configured to engage with a ring-shaped rotor 811. The stator 810 comprises a first set of piezoelectric actuators 801a and _{a second set of piezoelectric actuators 801b. An alternating electrical voltage may be selectively and exclusively applied to either set of} piezoelectric actuators 801a, 801b while the other set is left floating. In such a case, the set to which the voltage is applied is referred to as active, while the other set is referred to as free. The stator 810 comprises a number of protrusions 815. The stator 810 is configured to _{engage with the rotor 811 via the protrusions 815. The rotor 811 is configured to be attached to the load or mechanism to be moved.} _{[211] A standing wave vibration pattern may be excited in the stator 810 in response to the applied voltage. As a result, the protrusions} 815 oscillate at a first angle with respect to the top surface of the stator 810 when the piezoelectric actuators 801a are active. The protrusions 815 oscillate at a second angle with respect to the top surface of the stator 810 when the piezoelectric actuators 801b are active, with the second angle different from the first angle. The first angle is such that the stator 810 imparts a clockwise rotary motion to the rotor 811. The second angle is such that the stator 810 imparts a counter-clockwise rotary motion to the rotor 811. _{[212] In the embodiment shown in Fig. 24, the rotary ultrasonic motor MO has a rotational speed in the range of 10 mrad/s – 10,000} _{mrad/s. and produces a torque in the range of 20 Nmm – 450 Nmm.} _{[213] Rotary ultrasonic motors, such as the SWUSM or TWUSM, configured to generate rotary motion, can be used as the rotational} electrical motor. Such a rotary ultrasonic motor configured to generate rotary motion can be used to generate rotary motion of the infusion needle 11 in those embodiments where the needle 11 is rotatable. _{[214] Fig. 25 shows an embodiment of a linear ultrasonic motor MO. The linear ultrasonic motor MO comprises a piezoelectric actuator} _{801, a pushing member 816, and a movable member 805 (or slider). The piezoelectric actuator 801 vibrates at its resonance frequency in} _{response to an applied alternating voltage. The piezoelectric actuator 801 is attached to the pushing member 816. As a result of the} vibrations in the piezoelectric actuator 801, the pushing member 816 alternatively contacts the movable member 805 and makes it move linearly by frictional coupling. _{[215] In the embodiment shown in Fig. 25, the linear ultrasonic piezo motor MO is configured to generate linear motion with a speed in} _{the range of 4 mm/s to 100 mm/s and a force in the range of 0.5 N – 30 N. As the maximum stroke is limited by the length of the movable} _{member 805 (also called a slider), there is no set limit for the maximum stroke.} _{[216] This configuration of a linear ultrasonic piezo motor creating a linear motion can be used to generate the linear motion of the} infusion needle 11. _{[217] Fig. 26A illustrates an embodiment of a piezoelectric pump P configured to be implanted in the body of a patient. The piezoelectric} pump P comprises a chamber 831a, a diaphragm 832a and a wall. The wall comprises a wall portion 833a. The diaphragm 832a is connected to the wall portion 833a, such that the wall portion 833a and the diaphragm 832a enclose the chamber 831a. The wall portion 833a comprises an inlet 834a and an outlet 835a. The inlet 834a and the outlet 835a are configured to connect the chamber 831a with an inlet reservoir (not shown) and an outlet reservoir (not shown), respectively. The diaphragm 832a is configured to bend such that the volume of the chamber varies _{[218] The piezoelectric pump P is configured to be operated in a supply mode and a pump mode, as shown in Fig. 26B and Fig. 26C,} respectively. In the supply mode, the diaphragm 832a bends downwards such that the volume of the chamber 831a increases, thereby decreasing the pressure in the chamber 831a compared to the inlet reservoir. Thus, an amount of fluid is supplied by the inlet reservoir to the chamber 831a via the inlet 834a. In the pump mode, the diaphragm 832a bends upwards such that the volume of the chamber 831a decreases, thereby increasing the pressure in the chamber 831a compared to the outlet reservoir. Thus, an amount of fluid is pumped from the chamber 831a to the outlet reservoir via the outlet 835a. _{[219] The piezoelectric pump P comprises a driving element 836. The driving element 836 is coupled to the diaphragm 832a. A} controller (cf. Fig.34) is configured to control the action of the driving element 836. _{[220] In some embodiments, the driving element 836 is a piezoelectric actuator, e.g. a bimorph piezoelectric actuator or any of the} piezoelectric actuators herein disclosed. The driving element 836 is configured to be connected to a voltage generator. In response to an applied voltage, the driving element 836 deforms elastically, thereby imparting stress to the diaphragm 832a. As a result, the diaphragm 832a bends downwards or upwards depending on the applied voltage. _{[221] In other embodiments, the driving element 836 is driven by a piezoelectric motor. In these embodiments, the diaphragm 832a} bends downwards or upwards in response to a mechanical displacement of the driving element 836 induced by the piezoelectric motor. Any _{one of the motors MO in Figs. 18 to 25 may be a piezoelectric motor.} _{[222] In any of the embodiments herein disclosed, the diaphragm 2a may comprise bellows 852, as shown in Fig. 27. The bellows 852} enable the contraction and expansion of the diaphragm 2a by means of the elasticity of the bellows 852. In particular, in the embodiment _{shown in Fig. 27, the bellows 852 is a metal bellows 852, in particular a titanium bellows 852. As the chamber 831a comprises the titanium} bellows 852, at least a portion of the wall portion 833a being in contact with the fluid in the chamber 831a comprises metal, namely titanium. Metals are generally dense, which is advantageous as fluids do not diffuse through metals as easily. This reduces the risk that fluid diffuses from the chamber 831a or that fluids diffuse into the chamber 831a. In the embodiment shown in Fig.27, the entire wall enclosing the chamber 831a is made from metal, in particular titanium. In embodiments in which the wall enclosing the chamber is made from a composite of metallic or non-metallic materials, the non-metallic materials could be provided as a layer or a coating applied or sprayed _{onto the metal. In some embodiments, at least 50% of the area of the wall enclosing the chamber 831a comprises metal, and in alternative} embodiments at least 80% of the area of the wall enclosing the chamber 831a comprises metal, and in yet alternative embodiments at least 90% of the area of the wall enclosing the chamber 831a comprises metal. _{[223] Referring again to Figs. 26A to 26C, the wall may further comprise a wall portion 833b and the piezoelectric pump P a chamber} 831b. In this case, the diaphragm 832a is connected to the wall portion 833b such that the wall portion 833b and the diaphragm 832a enclose the chamber 831b. The chamber 831a and chamber 831b are separated by the diaphragm 832a. The chamber 831a and chamber 831b are configured to contain a first fluid and a second fluid, respectively, the two fluids being possibly different. The chamber 831a is sealed from the chamber 831b, thereby preventing mixing of fluids between the two chambers. The fluid in the chamber 831b may be a gas, _{e.g. air. The sealing of the chamber 831a from chamber 831b is advantageous. In fact, a component unsuitable to be in contact with the fluid} in the chamber 831a may be hosted by the chamber 831b. Such a component may be the driving element 836. _{[224] In some embodiments, the piezoelectric pump P may further comprise a diaphragm 832b connected to the wall portion 833b. In} these embodiments, the wall portion 833b and the diaphragm 832b enclose the chamber 831b. Both the diaphragm 832a and diaphragm 832b are coupled to the driving element 836. In response to the action of the driving element 836, the diaphragm 832a and diaphragm 832b bend towards the same direction, i.e. upwards or downwards. The driving element 836 may be interposed between the diaphragm 832a and diaphragm 832b to prevent contact of the driving element 836 with the fluid in any of the chambers 831a and 831b. Alternatively, the wall portion 833b may be open, such that no chamber 831b is formed. Then the driving element 836 is interposed between the diaphragm 832a and diaphragm 832b to prevent contact of the driving element 836 with, for instance, the fluid in the chamber 831a or the body of the patient. In some embodiments, the diaphragm 832b may comprise bellows 852. Then, the same considerations made on the _{diaphragm 832a, wall portion 833a and chamber 831a in connection with Fig.27 apply, mutatis mutandis, to the diaphragm 832b, wall} portion 833b and chamber 831b. _{[225] In any of the embodiments herein disclosed in which the wall portion 833b encloses the chamber 831b, the chamber 831b may be} configured to be connected to a pressure adapter 861, as shown in Fig.28. In particular, in the embodiment in Fig.28 the pressure adapter 861 comprises a substantially stiff portion 862, an elastic portion 863 and a conduit 864. The elastic portion 863 is attached to the rigid portion 862, and connected to the conduit 864. The conduit 864 is configured to be connected to the chamber 831b via an opening 865 to enable variation of pressure in the chamber 831b. The volume enclosed by the elastic portion 863 increases when the pressure in the _{chamber 831b increases. Vice versa, the volume enclosed by the elastic portion 863 decreases when the pressure in the chamber 831b} decreases. In some embodiments, the elastic portion 863 is configured to maintain the same surface area when the volume enclosed by the _{elastic portion 863 varies. This is advantageous in that a fibrotic tissue, as disclosed herein, which at least partially covers the elastic} portion 863 may easily adapt to the elastic portion 863. _{[226] The inlet 834a and the outlet 835a comprise an inlet valve 837a’ and an outlet valve 838a’, respectively. The inlet valve 837a’ and} the outlet valve 838a’ are check valves, e.g. ball valves, bridge-type valves and cantilever-type valves. Check valves are configured to enable fluid flow in one direction while preventing backflow in the opposite direction. The inlet valve 837a’ is configured to enable fluid flow _{from the inlet reservoir to the chamber 831a, while preventing backflow in the opposite direction. Likewise, the outlet valve 838a’ is} configured to enable fluid flow from the chamber 831a to the outlet reservoir, while preventing backflow in the opposite direction. _{[227] In other embodiments, the inlet valve 837a’ and the outlet valve 838a’ are active valves, i.e. valves controlled by a driving} element. The driving element may be an actuator, e.g. a piezoelectric actuator, or a motor, e.g. a piezoelectric motor. A controller (cf. Fig. 34) is configured to synchronize the opening and closing of the active valves so as to enable fluid transfer from the inlet 834a to the outlet 835a. _{[228] Fig. 29A and Fig. 29B illustrate an embodiment of a ball valve 841 when enabling or inhibiting fluid flow, respectively. The ball valve} comprises a flow control element 842, e.g. a ball, and a conduit 843. The conduit 843 comprises a portion 843a and a portion 843c. The conduit 843 further comprises a portion 843b connecting the conduit portion 843a and conduit portion 843c. The flow control element 842 _{is configured to move along the conduit portion 843c. The size of the flow control element 842 is such that the flow control element 842} cannot pass from the conduit portion 843c to the conduit portion 843a. For instance, if the flow control element 842 is a ball, the diameter _{of the ball is larger than a cross-section of a conduit portion 843b. When the pressure in the conduit portion 843a is larger than the} _{pressure in the conduit portion 843c, the flow control element is pushed away from the conduit portion 843b and fluid flow is enabled from} the conduit portion 843a to the conduit portion 843c. On the contrary, when the pressure in the conduit portion 843c is larger than the pressure in the conduit portion 843a, the flow control element 842 seals the conduit portion 843b such that fluid flow is inhibited from the conduit portion 843c to the conduit portion 843a. _{[229] Fig. 30A and Fig. 30B illustrate an embodiment of a piezoelectric pump P operating in the supply mode and pump mode,} respectively. The piezoelectric pump P is configured to be implanted in the body of a patient. In this embodiment, the inlet valve 837a’ and outlet valve 838a’ (cf. Figs.26A to 26C) are replaced by a static element 837a’’ and a static element 838a’’, respectively. The static element 837a’’ and static element 838a’’ are configured to control the fluid flow throughout the chamber 831a while maintaining a static geometry. The static element 837a’’ comprises a passage 839a’’ with an increasing cross-sectional area when entering the chamber 831a. On the contrary, the static element 838a’’ comprises a passage 840a’’ with a decreasing cross-sectional area when entering the chamber 831a. The static element 837a’’ and static element 838a’’ are advantageous in that they are more resistant to wear and fatigue failure as compared to check valves and active valves. In fact, maintenance or replacement of an implantable device, such as the piezoelectric pumps disclosed herein or any of their components, pose risks for the patient. _{[230] In the supply mode (cf. Fig.30A), the static element 837a’’ acts as a diffuser and the static element 838a’’ acts as a nozzle. An} amount of fluid may enter the chamber 831a from the outlet 835a. However, the passage 839a’’ opposes a lower flow restriction than the passage 840a’’. As a result, the amount of fluid flowing into the chamber 831a via the inlet 834a is larger than the amount of fluid flowing into the chamber 831a via the outlet 835a. In the pump mode (cf. Fig.30B), the static element 837a’’ acts as a nozzle and the static element 838a’’ acts as a diffuser. An amount of fluid may exit the chamber 831a from the inlet 834a. However, the passage 840a’’ opposes a lower flow restriction than the passage 839a’’. As a result, the amount of fluid flowing out of the chamber 831a via the outlet 835a is larger than the amount of fluid flowing out of the chamber 831a via the inlet 834a. _{[231] An embodiment of a piezoelectric pump P is illustrated in Fig. 31. The piezoelectric pump P is configured to be implanted in the} body of a patient. The piezoelectric pump P is configured to be operated in a double mode, as illustrated in the following. The piezoelectric pump P comprises an upper portion Pa and a lower portion Pc. The upper portion Pa comprises a chamber 831a, a diaphragm 832a and a wall portion 833a. The diaphragm 832a is connected to the wall portion 833a such that the wall portion 833a and the diaphragm 832a enclose the chamber 831a. The wall portion 833a comprises an inlet 834a and an outlet 835a. The inlet 834a and the outlet 835a are configured to connect the chamber 831a with a first inlet reservoir (not shown) and first outlet reservoir (not shown), respectively. The inlet 834a comprises an inlet valve 837a’ or a static element 837a’’. The outlet 835a comprises an outlet valve 838a’ or a static element 838a’’. _{[232] The lower portion Pc comprises a chamber 831c, a diaphragm 832c and a wall portion 833c. The diaphragm 832c is connected to} the wall portion 833c such that the wall portion 833c and the diaphragm 832c enclose the chamber 831c. The wall portion 833c comprises an inlet 834c and an outlet 835c. The inlet 834c and the outlet 835c are configured to connect the chamber 831c with a second inlet reservoir (not shown) and a second outlet reservoir (not shown), respectively. The inlet 834c comprises an inlet valve 837c’ or a static _{element 837c’’. The outlet 835c comprises an outlet valve 838c’ or a static element 838c’’. The chamber 831a and chamber 831c are} configured to contain a first fluid and a second fluid, respectively, the two fluids being possibly different. The chamber 831a is sealed from the chamber 831c, thereby preventing mixing of fluids between the two chambers. _{[233] The diaphragm 832a and diaphragm 832c are coupled and configured to bend towards the same direction, i.e. upwards or} downwards. A driving element 836, e.g. a piezoelectric actuator or any other driving element herein disclosed, is coupled to the diaphragm 832a and diaphragm 832c. In response to the action of the driving element 836, the diaphragm 832a and diaphragm 832c bend towards the _{same direction, i.e. upwards or downwards. The driving element 836 may be interposed between the diaphragm 832a and diaphragm 832b} to prevent contact of the driving element 836 with the fluid in any of the chambers 831a and 831c. In some embodiments, the diaphragm 832c may comprise bellows 852. Then, the same considerations made on the diaphragm 832a, wall portion 833a and chamber 831a in connection with Fig.27 apply, mutatis mutandis, to the diaphragm 832c, wall portion 833c and chamber 831c. _{[234] The variation of the volume of the chamber 831a, due to a bending of the diaphragm 832a, is mirrored by an equal opposite} variation of the volume of the chamber 831c, due to a bending of the diaphragm 832c. As a result, when the upper portion Pa operates in a supply mode, the lower portion Pc operates in the complementary mode, i.e. the pump mode. Vice versa, when the upper portion Pa operates in a pump mode, the lower portion Pc operates in the complementary mode, i.e. the supply mode. The double mode configuration illustrated in Fig.31 is advantageous in that a single driving element 836 simultaneously drives two chambers. Therefore, a piezoelectric pump P configured to be operated in a double mode may be cheaper, more space-efficient and more energy-efficient as compared to two independent piezoelectric pumps, each having its own driving element. It may also eliminate the need for an enclosed gas in the implant. _{[235] Fig. 32 shows an embodiment of a piezoelectric pump P comprising at least a first portion PL and a last portion PR connected in} series. The series may comprise additional portions. Each of the portions may be any of the embodiments disclosed with reference to Figs. _{26A to 26C and Figs. 30A and 30B. The piezoelectric pump P is configured to be implanted in the body of a patient. The outlet of the first} portion PL is configured to be connected to the inlet of the next portion of the series. The inlet of the last portion PR is configured to be _{connected to the outlet of the previous portion of the series. The inlet of each of the portions other than the first portion PL and last portion} PR, if any, is configured to be connected to the outlet of the previous portion of the series. The outlet of each of the portions other than the _{first portion PL and last portion PR, if any, is configured to be connected to the inlet of the next portion of the series. The piezoelectric pump} P is configured to transfer an amount of fluid from an inlet reservoir, configured to be connected to the inlet 834a of the first portion PL, to an outlet reservoir, configured to be connected to the outlet 835a of the last portion PR. This amount of fluid passes, sequentially, through the chamber 831a of the first portion PL, the chambers 831a of the next portions, if any, and the chamber 831a of the last portion PR. A _{controller (cf. Fig. 34) is configured to synchronize the action of the driving elements of the portions of the series. Thus, the bending of the} _{diaphragms of the portions of the series is synchronized so as to create the pressure required for the fluid transfer. If any of the inlet and} outlets comprises an active valve, the opening and closing of any of the active valves is controlled by the controller so as to enable the fluid _{transfer. The series connection allows for larger pressure compared to piezoelectric pumps in which fluid is transferred from an inlet to an} outlet reservoir via a single chamber. _{[236] In another embodiment (not shown), a piezoelectric pump P is provided comprising at least a first portion PL and a last portion} PR connected in series. The series may comprise additional portions. The piezoelectric pump P is configured to be operated in a double mode. Each of the portions of the series may correspond to the embodiment disclosed with reference to Fig.31. Thus, each of the portions of the series may be configured to be operated in a double mode. Then, the outlet 835a of the first portion PL is configured to be connected to the inlet 834a of the next portion of the series, and the outlet 835c of the first portion PL is configured to be connected to the inlet 834c of the next portion of the series. The inlet 834a of the last portion PR is configured to be connected to the outlet 835a of the previous portion of the series, and the inlet 834c of the last portion PR is configured to be connected to the outlet 835c of the previous portion of the series. The inlet 834a of each of the portions other than the first portion PL and last portion PR, if any, is configured to be connected to the outlet _{835a of the previous portion of the series. The inlet 834c of each of the portions other than the first portion PL and last portion PR, if any, is} configured to be connected to the outlet 835c of the previous portion of the series. The outlet 835a of each of the portions other than the first portion PL and last portion PR, if any, is configured to be connected to the inlet 834a of the next portion of the series. The outlet 835c of each of the portions other than the first portion PL and last portion PR, if any, is configured to be connected to the inlet 834c of the next portion of the series. The piezoelectric pump P is configured to transfer an amount of a first fluid from a first inlet reservoir, configured to _{be connected to the inlet 834a of the first portion PL, to a first outlet reservoir, configured to be connected to the outlet 835a of the last} portion PR. This amount of fluid passes, sequentially, through the chamber 831a of the first portion PL, the chambers 831a of the next portions, if any, and the chamber 831a of the last portion PR. The piezoelectric pump P is further configured to transfer an amount of a second fluid from a second inlet reservoir, configured to be connected to the inlet 834c of the first portion PL, to a second outlet reservoir, configured to be connected to the outlet 835c of the last portion PR. This amount of fluid passes, sequentially, through the chamber 831c of the first portion PL, the chambers 831c of the next portions, if any, and the chamber 831c of the last portion PR. A controller (cf. Fig.34) is configured to synchronize the action of the driving elements of the portions of the series. Thus, the bending of the diaphragms of the portions of the series is synchronized so as to create the pressure required for the fluid transfer. If any of the inlet and outlets comprises an active valve, the opening and closing of any of the active valves is controlled by the controller so as to enable the fluid transfer. The _{series connection allows for larger pressure as compared to piezoelectric pumps configured to be operated in a double mode in which a} first fluid is transferred from a first inlet reservoir to a first outlet reservoir via a single first chamber and a second fluid is transferred from a second inlet reservoir to a second outlet reservoir via a single second chamber. _{[237] Fig.33 shows an embodiment of a piezoelectric pump P comprising at least a first portion PU and a last portion PD connected in} parallel. The parallel connection may comprise additional portions. Each of the portions may be any of the embodiments disclosed with reference to Figs.26A to 26C and Figs.30A and 30B. The piezoelectric pump P is configured to be implanted in the body of a patient. The inlet of each portion is configured to be connected to an inlet reservoir. The outlet of each portion is configured to be connected to an outlet reservoir. The piezoelectric pump P is configured to transfer an amount of fluid from the inlet reservoir to the outlet reservoir. A controller (cf. Fig.34) is configured to synchronize the action of the driving elements of the portions of the parallel connection in order to ensure synergetic operation, wherein, at a given operation stage, each portion operates in the same mode, i.e. either in the supply mode or pump mode. If any of the inlet and outlets comprises an active valve, the opening and closing of any of the active valves is controlled accordingly by the controller. The parallel connection allows for a higher flow rate as compared to piezoelectric pumps in which the inlet reservoir is _{configured to be connected to a single inlet and the outlet reservoir is configured to be connected to a single outlet.} _{[238] In another embodiment (not shown), a piezoelectric pump P is provided comprising at least a first portion PU and a last portion} PD connected in parallel. The parallel connection may comprise additional portions. Each of the portions may correspond to the embodiment disclosed with reference to Fig.31. Thus, each of the portions of the parallel connection is configured to be operated in a double mode. Then the inlet 834a and inlet 834c of each portion are configured to be connected to a first inlet reservoir and second inlet reservoir, respectively. The outlet 835a and outlet 835c of each portion are configured to be connected to a first outlet reservoir and second outlet reservoir, respectively. The piezoelectric pump P is configured to transfer an amount of a first fluid from the first inlet reservoir to the first outlet reservoir. The piezoelectric pump P is further configured to transfer an amount of a second fluid from the second inlet reservoir to the second outlet reservoir. A controller (cf. Fig.34) is configured to synchronize the action of the driving elements of the portions of the parallel connection in order to ensure synergetic operation. Thus, at a given operation stage, the chamber 831a of each portion operates in _{the same mode, i.e. either in the supply mode or pump mode, and the chamber 831b of each portion operates in the complementary mode. If} any of the inlet and outlets comprises an active valve, the opening and closing of any of the active valves is controlled accordingly by the controller. The parallel connection allows for a higher flow rate as compared to piezoelectric pumps configured to be operated in a double mode in which the first inlet reservoir and second inlet reservoir are configured to be connected to a single first inlet and single second inlet, respectively, and the first outlet reservoir and second outlet reservoir are configured to be connected to a single first outlet and single second outlet, respectively. _{[239] The piezoelectric pumps herein disclosed are configured to be operated with a flow rate in the range of 0.01 ml/min to 35} ml/min and a pressure in the range of 0.2 kPa to 36 kPa. _{[240] Fig.34 shows an embodiment of a piezoelectric pumping system configured to be implanted in the body of a patient. The system} comprises a piezoelectric pump, an inlet reservoir, an outlet reservoir and a controller. The piezoelectric pump may be any of the piezoelectric pumps herein disclosed. The controller is configured to control the piezoelectric pump. The piezoelectric pumping system may comprise a sensor and a feedback unit. The sensor is configured to measure a parameter of the piezoelectric pump, such as flow rate and pressure. Based on the sensor measurement and a set value of the measured parameter, the feedback unit sends a conditioning signal to the controller. Thus, the controller adjusts the control of the piezoelectric pump in order for the measured parameter to achieve the set value. _{[241] Figs. 35A and 35B show an eighteenth embodiment of the present disclosure, according to the fourth aspect of the present} disclosure, namely a breast implant 10. The fluid chamber 1 comprises a frame 20 as, e. g., in the first to seventh embodiment, for giving the _{breast implant 10 some stability, wherein the frame 20 is configured to being implanted close to the patient's thorax. The outer layer 4 on the} fluid chamber 1 is optional, as is the frame 20. In any case, the fluid chamber 1 has a flexible outer shape which is preferably non-stretchable. _{[242] According to a first variant of the fourth aspect of the present disclosure, the fluid chamber 1 contains a Bingham fluid as a filling.} A Bingham fluid is characterised in that it behaves at a given temperature, which is chosen here as the body temperature of 37°C, as a rigid body at stresses below a predetermined yield stress and starts to flow at stresses exceeding the yield stress. A typical example of a Bingham _{fluid which everyone knows is tooth paste, but there are many other and different Bingham fluids available. It is well known to those skilled in} the art to adjust and select a Bingham fluid with the desired characteristics. According to a first alternative, a Bingham fluid is chosen having a yield stress so that it does not flow under its own weight. As a result, the shape of the breast implant 10 can be changed post-operatively by manually compressing the breast implant so as to make the Bingham fluid flow and, then, the breast implant 10 remains in the changed shape unless forces exceeding gravitational forces act thereon. According to a second alternative, a Bingham fluid is chosen having a yield stress slightly below the stress caused in the material due to gravitational forces, i. e. by its own weight. This way, the breast implant 10, after being reshaped manually, assumes its regular shape automatically over time. In this second alternative, the regular shape depends on the _{patient’s position. That is, when the patient rests on the back, the regular shape will be relatively flat, whereas the shape of the breast implant} will become drop-like, as shown in Fig.35A, when the upper body of the patient is upright for a longer time. _{[243] While a Bingham fluid falls within the group of plastic fluids, the filling of the fluid chamber 1 may alternatively, according to a second} variant, comprise a viscoelastic material. Viscoelastic materials exhibit both viscous and elastic characteristics. Therefore, the breast implant 10 always tends to assume a certain "regular" shape. Thus, when the breast implant 10 is deformed so that the predetermined shape of the _{breast implant changes, it tends to return to its predetermined shape due to the elasticity of the material. However, because of the viscous} characteristics of the material, such return does not occur immediately but takes place over time. Accordingly, by choosing a viscoelastic material with a high viscosity and/or low elasticity, the breast implant 10 can be adjusted so that the return to its predetermined shape occurs very slowly. For instance, the return of the breast implant 10 from the shape shown in Fig.35A to the shape shown in Fig.35B, or vice versa, may take one hour or more. Of course, the gravitational forces acting on the breast implant 10 have also a slight influence on the return behavior. _{[244] Figs. 36A and 36C show a nineteenth embodiment of the present disclosure , according to the fourth aspect of the present} disclosure, namely again a breast implant 10. Here, instead of a Bingham fluid or viscoelastic material, the filling comprises a memory foam, preferably a low-resistance polyurethane foam (LRPu). The memory foam is an open cell foam providing a matrix through which a fluid can flow. The fluid is preferably air. The memory foam may be considered a special kind of viscoelastic material. The elasticity results from the matrix provided by the open cells, whereas the viscosity results from pneumatic, adhesive and relaxation effects. The pneumatic effect is caused by the time for the fluid to flow through the foam's porous structure. The adhesive effect is caused by the stickiness of the surfaces within the foam when the internal pores within the foam are pressed together. And the relaxation effect, which is the strongest of the three forces working against the restoration of the foam towards its original form, is caused by the foam’s material being near its glass transition temperature which limits its mobility and slows the return of the foam to its original form once the applied pressure is removed. Since the _{effects are temperature-dependent, a memory foam is chosen which provides the desired effect at a temperature of about 37 °C. In this} regard, smaller pores lead to a higher internal surface area and reduced air flow, increasing the adhesion and pneumatic effects so that the foam’s properties can be controlled by changing its cell structure and porosity, whereas the glass transition temperature can be modulated with additives in the foam’s material. _{[245] Fig. 36A shows the breast implant 10 in its predetermined "regular" shape. The fluid chamber 1 is connected to a fluid chamber 2} via a conduit 19. Upon compression of the breast implant 10, as indicated by arrows in Fig.36B, fluid will flow from the memory foam through the conduit 19 into the second fluid chamber 2 so that the size decreases and the shape changes from relatively high to relatively flat. The breast implant 10 can be further deformed, as shown in Fig.36C. From this deformed state, the breast implant 10 can slowly return to its regular shape due to the elastic properties of the memory foam, wherein fluid will be drawn from the second fluid chamber 2 back into the memory foam contained in the fluid chamber 1 so that the breast implant 10 will ultimately return to its original predetermined shape shown in Fig.36A. _{[246] A flow control device (not shown) may be arranged between the first and second fluid chambers 1 and 2, for instance within the} conduit 19, such as the flow control device 24 as described above in relation to the first to fifteenth embodiments. _{[247] Figs.37A and 37B show a twentieth embodiment of the present disclosure, according to the fourth aspect of the present disclosure,} which is a variant of the embodiment shown in Figs.36A to 36C. That is, also in this embodiment does the breast implant 10 contain a filling in the fluid chamber 1 which comprises a memory foam. However, in this embodiment fluid cannot escape from the memory foam when the memory foam is deformed. Accordingly, the relaxation effect caused by the foam's material being near its glass transition temperature is the major effect which creates a force working to restore the foam's original structure after it has been deformed. The pneumatic and adhesive effects are relatively little as compared thereto. Nevertheless, if the breast implant 10 is deformed from its predetermined original shape, as shown in Fig.37A, to a modulated shape, as shown in Fig.37B, i. e. from high to flat in this particular example, it will slowly return to its original predetermined form over time due to the elastic properties of the memory foam. _{[248] Figs. 38A and 38B show a breast implant 10 of twenty-first embodiment of the present disclosure, according to the fifth aspect of} the present disclosure. Again, the breast implant 10 may or may not comprise the frame 20 and/or the outer layer 4. In any case, the fluid _{chamber 1 has a flexible outer shape. Overall, the structure of the breast implant 10 is not any different from the breast implants 10 of the} embodiments shown in Figs.35 to 37, except that the filling is different. Namely, the fluid chamber 1 contains a great number of elements 21, which are displaceably contained in the fluid chamber 1, and a lubricating fluid FT which fills spaces between the elements 21. Instead of the great number of elements 21, only one or a few displaceable elements 21 may be present in the fluid chamber 1, similar to the 11th to 13th embodiments described above in relation to Figs.11 to 13. That is, the fluid chamber 1 may further contain one or more non-displaceable elements 22, and the elements 21 and/or 22 may be inflatable or deflatable, e. g. by exchanging fluid between the first and second elements 21 and 22. _{[249] What is important in this fifth aspect of the present disclosure are the characteristics of the lubricating fluid FT which is present} between the elements 21 (or 21 and 22), as this is a thixotropic fluid. Thixotropic fluids have a shear thinning property which is time-dependent. This means that the fluid, when subjected to shear-stress, becomes less viscous, i. e. more fluent, whereas it is thick or viscous under static conditions. When the shear-stress is removed, the viscosity of the material returns from thin to thick over time. The thixotropic fluid is preferably chosen such that, at a body temperature of 37 °C and when not exposed to shear stress, it bonds the elements 21 to surfaces contacting those elements 21. Surfaces contacting those elements 21 are the surfaces of neighbouring elements 21 as well as an inner surface of the fluid chamber 1. _{[250] Fig.38A shows a breast implant 10 in a first state under static conditions. In this state, the thixotropic fluid FT is highly viscous and} bonds the elements 21 together. Upon compressing and walking the breast implant 10, the thixotropic fluid becomes less viscous, i. e. fluent, so that the breast implant 10 can be reshaped, e. g. to a shape as shown in Fig.38B. When the patient terminates the compressing and walking process, the viscosity of the thixotropic fluid increases again and bonds the elements or spheres together at their new position. _{[251] This effect is the better, the more elements there are in the fluid chamber 1. Preferably, the elements 21 take the form of spheres,} preferably 1000 spheres or more. These spheres may be irregular, but they are preferably perfectly round as this facilitates the movement of the spheres past each other during the compressing and walking process. _{[252] Figs. 39a to 39C show a twenty-second embodiment of the present disclosure, according to the sixth aspect of the present} disclosure. The overall structure of the breast implant 10 of this twenty-second embodiment is similar to the structure of the breast implant 10 of the twenty-first embodiment. That is, the breast implant 10 may contain one or more elements 21 which may take the form of regular or irregular spheres, in particular 1000 or more of those spheres, and which are displaceably contained in the fluid chamber 1. A port 31 is provided for supplying a lubricating fluid into the fluid chamber 1 in order to reduce surface friction between an outer surface of the elements _{21 and surfaces contacting the outer surface of the elements 21. In the embodiment shown in Fig. 39A, the port 31 is a self-sealing injection} port for injecting lubricating fluid by means of a syringe from outside the breast implant 10, when the breast implant 10 is implanted. _{Alternatively, the port may be arranged so as to connect the fluid chamber 1 with a second fluid chamber, such as any of the second fluid} chambers 2 in the embodiments discussed above in relation to Figs.11 to 14. _{[253] What is important for the breast implant 10 or breast implant system according to the sixth aspect of the present disclosure is} that lubricating fluid may be added to and removed from the fluid chamber 1 and that either the inner surface of the fluid chamber 1 or the outer surface of the elements 21 have recesses. The recesses have the purposes of facilitating distribution of the lubricating fluid within the fluid chamber 1 when the lubricating fluid is introduced into the fluid chamber 1. Preferably, both the inner surface of the fluid chamber 1 and the outer surface of the elements 21 have those recesses. _{[254] In the embodiment shown in Figs. 39A to 39C, recesses 4a are provided on the inner surface of the outer layer 4, which – in this} _{embodiment – forms one part of the wall of the fluid chamber 1. Recesses 3a are further provided on the inner surface of the back wall 3} _{which – in this embodiment – forms another part of the wall of the fluid chamber 1. These recesses 3a and 4a have the form of grooves which} extend from the port 31 and along the wall of the fluid chamber 1 so as to facilitate the distribution of the lubricating fluid. _{[255] Fig. 40 shows a twenty-third embodiment of the present disclosure, according to the sixth aspect of the present disclosure. Here,} grooves 21a are formed on the outer surface of the element 21 contained in the fluid chamber 1 of the breast implant shown in Fig.39A, wherein the elements 21 preferably take the form of regular spheres. The grooves 21a are connected to other grooves 21a so as to further support distribution of the lubricating fluid along the surface of the elements 21. _{[256] Fig. 41 shows a twenty-fourth embodiment of the present disclosure, according to the sixth aspect of the present disclosure. Fig.} _{41 shows an element 21 in which the recesses 21a on the surface of the element 21 are provided in the form of valleys between elevations. The} valleys and elevations may be irregular or regular, just like the grooves 21a in the embodiment shown in Fig.40 may be irregular or regular. _{[257] Turning back to the twenty-second embodiment of Figs. 39a to 39C and the port for supplying lubricating fluid to the fluid chamber} 1, which is provided as a self-sealing injection port 31, this self-sealing injection port 31 is arranged, according to the seventh aspect of the present disclosure, on the fluid chamber 1 at a location where it can be easily pierced with a syringe from outside the breast implant, when the breast implant 10 is implanted in a patient's breast. The self-sealing characteristic of the injection port 31 may be due to a self-sealing membrane in the injection port itself or by a self-sealing material of the outer layer underlying the injection port 31, which is then considered to make part of the self-sealing injection port 31. The membrane and/or outer layer 4 may comprise a silicone material, as an example. The port 31 should be tactilely perceivable by the patient through the patient's skin covering the injection port 31, so that it can be easily retrieved and a lubricating syringe easily introduced into the fluid chamber 1 through the injection port 31. _{[258] Preferred aspects of the present disclosure are summarized in the following paragraphs:} FIRST AND SECOND ASPECTS: AUTOMATIC REFLOW _{480SE - FIRST ASPECT: THROTTLED REFLOW} _{1. A breast implant system, comprising:} _{- a plurality of chambers including a first fluid chamber and a second fluid chamber, said first and second fluid chambers being} _{adapted for implantation in a human body with the first fluid chamber forming part of a breast implant, said first and second fluid} _{chambers being interconnected when implanted for fluid to be transferred between the first and second fluid chambers so as to change} their respective fluid content, -_{an energy storage configured to store energy when fluid is transferred between the first and second fluid chambers and further} configured to release the stored energy in a manner so as to re-transfer the transferred fluid between the first and second fluid chambers, and -_{a flow control device configured to control fluid transfer between the first and second fluid chambers, wherein the flow control} device comprises at least one of: -_{a throttle which is configured to permit throttled re-transfer of the transferred fluid between the first and} second fluid chambers automatically over time, and -_{a piston configured such that fluid transfer between the first and second fluid chambers is realized by means} of movement of the piston, wherein friction acting on the piston counteracts the release of the stored energy and is adjusted or adjustable such that re-transfer of the transferred fluid between the first and second fluid chambers occurs automatically over time. T_{he breast implant system of aspect 1, wherein the flow control device comprising the throttle further comprises a check valve which} is configured to permit free transfer of fluid between the first and second fluid chambers and prevent re-transfer of the transferred fluid through the check valve. T_{he breast implant system of aspect 1, wherein the flow control device comprising the piston further comprises a cylinder arranged} between the first and second fluid chambers, wherein the piston is movably arranged in the cylinder such that fluid transfer between the first and second fluid chambers is realized by means of movement of the piston in the cylinder causing a fluid transfer from the first fluid chamber to the cylinder and from the cylinder to the second fluid chamber, and vice versa. _{SE - SECOND ASPECT: REFLOW SWITCH (UNTHROTTLED OR THROTTLED)} _{A breast implant system, comprising:} _{- a plurality of chambers including a first fluid chamber and a second fluid chamber, said first and second fluid chambers being} _{adapted for implantation in a human body with the first fluid chamber forming part of a breast implant, said first and second fluid} _{chambers being interconnected when implanted for fluid to be transferred between the first and second fluid chambers so as to change} their respective fluid content, -_{an energy storage configured to store energy when fluid is transferred between the first and second fluid chambers and further} configured to release the stored energy in a manner so as to re-transfer the transferred fluid between the first and second fluid chambers, and -_{a flow control device configured to control fluid transfer between the first and second fluid chambers,} wherein the flow control device comprises a switch which is operable so as to switch the flow control device between a first state in which the flow control device is configured to permit free transfer of fluid between the first and second fluid chambers in a first direction while preventing transfer of fluid in a second direction opposite to the first direction and a second state in which the flow control device is configured to permit re-transfer of the transferred fluid between the first and second fluid chambers in the second direction. _{5. The breast implant system of aspect 4, wherein the flow control device comprises a check valve which is configured to permit the free} transfer of fluid between the first and second fluid chambers and prevent re-transfer of the transferred fluid through the check valve, w_{herein preferably the switch is pressure operable so as to switch the flow control device from the second state to the first state.} _{6. The breast implant system of aspect 4 or 5, wherein the flow control device is configured to permit unthrottled re-transfer of the} transferred fluid between the first and second fluid chambers in the second direction. _{7. The breast implant system of aspect 4 or 5, wherein the flow control device comprises a throttle which is configured to permit throttled} re-transfer of the transferred fluid between the first and second fluid chambers automatically over time _{8. The breast implant system of any one of aspects 4 to 7, wherein an actuator of the switch is mounted subcutaneously so as to be} operable manually. _{9. The breast implant system of any one of aspects 4 to 8, wherein the switch is a purely mechanical switch.} _{10. The breast implant system of aspect 9, wherein the mechanical switch is a hydraulic switch.} _{11. The breast implant system of any one of aspects 4 to 8, wherein the switch comprises an electric switch.} ENERGY STORAGE MEANS _{12. The breast implant system of any one of aspects 1 to 11, wherein the energy storage, which is configured to store energy when fluid is} transferred between the first and second fluid chambers, comprises an elastic wall which surrounds one of the first and second fluid chambers at least partly, wherein the elastic wall is configured to expand when fluid is transferred from the respective other one of the first and second fluid chambers into said one of the first and second fluid chambers. _{13. The breast implant system of any one of aspects 1 to 12, wherein the energy storage configured to store energy when fluid is transferred} between the first and second fluid chambers comprises a resilient element, wherein the resilient element is configured to expand one of the first and second fluid chambers. _{14. The breast implant system of aspect 13, wherein the resilient element is configured to expand the second fluid chamber.} _{15. The breast implant system of aspect 13 or 14, wherein the resilient element comprises a spring.} LUBRICATION _{16. The breast implant system of any one of aspects 1 to 15, comprising at least one element which is displaceably contained in the first} fluid chamber, wherein the second fluid chamber comprises a lubricating fluid so as to allow lubricating fluid to be supplied from the second fluid chamber to the first fluid chamber in order to reduce surface friction between an outer surface of said at least one element and surfaces contacting the outer surface of said at least one element. REMOTE RESERVOIR _{17. The breast implant system of any one of aspects 1 to 16, wherein the second fluid chamber is adapted for implantation within the human} body remote from the breast implant so as to form a reservoir for the first fluid chamber, the system further comprising at least one conduit between the remotely implantable second fluid chamber and the first fluid chamber for fluid exchange between the first and second fluid chambers. PLURAL CHAMBERS IN BREAST IMPLANT (no remote fluid reservoir) _{18. The breast implant system of any one of aspects 1 to 15, wherein the second fluid chamber forms part of the breast implant along with} the first fluid chamber. VARIABLE SHAPE, CONSTANT VOLUME _{19. The breast implant system of aspect 18, wherein the breast implant has a constant volume and a variable shape, the shape being variable} upon fluid exchange between the first and second fluid chambers. _{VARIABLE SHAPE AND VARIABLE VOLUME, BUT CONSTANT MASS} _{20. The breast implant system of any one of aspects 1 to 15, comprising a third fluid chamber, wherein:} _{- the second fluid chamber forms part of the breast implant along with the first fluid chamber,} _{- the first and second fluid chambers comprise an incompressible fluid,} _{- the third fluid chamber forms also part of the breast implant,} _{- the third fluid chamber comprises a compressible fluid, and} _{- an exchange of the incompressible fluid between the first and second fluid chambers results in an increase of pressure of the} compressible fluid within the third fluid chamber, wherein the increase of pressure within the third fluid chamber constitutes the energy storage. SERVO SYSTEM _{21. The breast implant system of any one of aspects 1 to 20, wherein the exchange of an amount of fluid between the first and second fluid} chambers involves a movement of an amount of fluid in at least one third fluid chamber which is different to the amount of fluid exchanged between the first and second fluid chambers. _{22. The breast implant system of aspect 21, wherein the at least one third fluid chamber comprises sub-chambers and wherein at least one} of said first and second fluid chambers is operatively connected to at least one of the sub-chambers and is adapted to expand or contract said sub-chamber when fluid is exchanged between the first and second fluid chambers, the sub-chambers being interconnected so as to allow fluid to flow into the expanded, or from the contracted, sub-chamber when fluid is exchanged between the first and second fluid chambers. _{23. The breast implant system of aspect 21 or 22, wherein at least one of the sub-chambers of the third fluid chamber is configured for} being implanted subcutaneously such that fluid can be exchanged between the sub-chambers by manually compressing the subcutaneously implantable sub-chamber. _{24. The breast implant system of any one of aspects 21 to 23, wherein a spring element is provided for urging the third fluid chamber or at} least one of the sub-chambers into a state of minimum or maximum volume. _{483SE - THIRD ASPECT: ENERGY RECEIVER IN STERNUM + MOTOR/PUMP IN BREAST IMPLANT (COMBINABLE WITH FIRST AND SECOND ASPECTS)} _{1. A breast implant system, preferably a breast implant system of any one of aspects 1 to 24, comprising:} _{- a plurality of chambers including a first fluid chamber and a second fluid chamber, said first and second fluid chambers being} _{adapted for implantation in a human body with the first fluid chamber forming part of a breast implant, said first and second fluid} chambers being interconnected when implanted for fluid to be transferred between the first and second fluid chambers so as to change t_{heir respective fluid content,} _{- at least one energy consuming part which forms part of the breast implant and} _{- an energy source for supplying energy to the at least one energy consuming part, wherein the energy source comprises a wireless} _{energy transmitter (29) configured to wirelessly transmit energy from outside the patient’s body and one or more than one energy} receiver configured to receive the wirelessly transmitted energy from the wireless energy transmitter (29), wherein the one or more than one energy receiver is configured for implantation within the patient’s body above the patient’s sternum. T_{he breast implant system of aspect 1, wherein the breast implant has a rigid back wall configured for being placed adjacent the patient’s} thorax, wherein the energy consuming part is contained in or on the back wall. T_{he breast implant system of aspect 1 or 2, wherein the energy consuming part comprises at least one of a motor and a pump.} _{The breast implant system of any one of aspects 1 to 3, wherein the energy source comprises an energy storage connected to the} energy consuming part for storing the wirelessly transmitted energy. T_{he breast implant system of any one of aspects 1 to 4, wherein the energy source comprises an implantable energy transforming} device for transforming the wirelessly transmitted energy into electric energy for direct use by the energy consuming part. _{SE - FOURTH ASPECT: VISCOPLASTIC OR VISCOELASTIC FILLING} _{A breast implant for implantation in a patient’s body, comprising at least one fluid chamber with a flexible outer shape and a filling in} the fluid chamber, wherein the filling comprises at least one of: -_{a Bingham fluid which behaves, at a normal body temperature of 37 °C, as a rigid body at stresses below a yield stress and starts} to flow at stresses exceeding the yield stress, wherein the yield stress of the Bingham fluid is preferably such that, on the one hand, t_{he Bingham fluid does not flow under its own weight and, on the other hand, the Bingham fluid is configured to flow when the fluid} _{chamber is manually compressed and deformed from outside the breast implant so that the shape of the breast implant can be changed} post-operatively by manually compressing the breast implant and remains in the changed shape unless forces exceeding gravitational forces act on the breast implant, -_{a viscoelastic material which exhibits both viscous and elastic characteristics, wherein the breast implant has a predetermined} shape defined by the viscoelastic material of the filling in the fluid chamber, wherein, when the breast implant is deformed so that the predetermined shape of the breast implant changes, the breast implant does not immediately return to its predetermined shape, due to the viscosity of the material, and returns to the predetermined shape over time due to the elasticity of the material, and -_{a memory foam.} _{A breast implant system comprising the breast implant of aspect 1, wherein:} _{- the filling in the fluid chamber of the breast implant comprises the memory foam, wherein the memory foam is an open cell foam} providing a matrix through which a fluid can flow, _{- the fluid chamber of the breast implant forms a first fluid chamber,} _{- the breast implant is connected to a second fluid chamber which is adapted for implantation within the human body remote from} the breast implant so as to form a reservoir for the first fluid chamber, and -_{the breast implant is configured such that compression of the fluid chamber causes fluid to flow out of the memory foam from the} _{fluid chamber into the second fluid chamber so that the volume of the breast implant decreases.} _{The breast implant system of aspect 2, wherein a flow control device is arranged between the first and second fluid chambers.} _{SE + 480SE - FOURTH ASPECT COMBINED WITH FIRST ASPECT: THROTTLED REFLOW} _{The breast implant system of aspect 3, wherein the flow control device comprises at least one of:} _{- a throttle which is configured to permit throttled re-transfer of the transferred fluid between the first and second fluid chambers} automatically over time, and -_{a piston configured such that fluid transfer between the first and second fluid chambers is realized by means of movement of the} piston, wherein friction acting on the piston counteracts the release of the stored energy and is adjusted or adjustable such that re- transfer of the transferred fluid between the first and second fluid chambers occurs automatically over time. T_{he breast implant system of aspect 4, wherein the flow control device comprising the throttle further comprises a check valve which} is configured to permit free transfer of fluid between the first and second fluid chambers and prevent re-transfer of the transferred fluid through the check valve. T_{he breast implant system of aspect 4, wherein the flow control device comprising the piston further comprises a cylinder arranged} _{between the first and second fluid chambers, wherein the piston is movably arranged in the cylinder such that fluid transfer between} _{the first and second fluid chambers is realized by means of movement of the piston in the cylinder causing a fluid transfer from the} _{first fluid chamber to the cylinder and from the cylinder to the second fluid chambers, and vice versa.} _{SE + 481SE - FOURTH ASPECT COMBINED WITH SECOND ASPECT: SWITCH / UNTHROTTLED OR THROTTLED REFLOW} _{The breast implant system of aspect 3, comprising a flow control device configured to control fluid transfer between the first and} second fluid chambers, the flow control device comprising a switch which is operable so as to switch the flow control device between a first state in which the flow control device is configured to permit free transfer of fluid between the first and second fluid chambers i_{n a first direction while inhibiting transfer of fluid in a second direction opposite to the first direction and a second state in which the} flow control device is configured to permit re-transfer of the transferred fluid between the first and second fluid chambers in the second direction. T_{he breast implant system of aspect 7, wherein the flow control device is configured to permit unthrottled re-transfer of the} transferred fluid between the first and second fluid chambers in the second direction. T_{he breast implant system of aspect 8, wherein the flow control device comprises a throttle which is configured to permit throttled re-} transfer of the transferred fluid between the first and second fluid chambers automatically over time T_{he breast implant system of aspect 8 or 9, wherein an actuator of the switch is mounted subcutaneously so as to be operable manually.} _{The breast implant system of any one of aspects 8 to 10, wherein the switch is a purely mechanical switch.} _{The breast implant system of aspect 11, wherein the mechanical switch is a hydraulic switch.} _{The breast implant system of any one of aspects 8 to 10, wherein the switch comprises an electric switch.} _{SE - FIFTH ASPECT: LUBRICATION WITH THIXOTROPIC FLUID} _{A breast implant for implantation in a patient’s body, comprising a fluid chamber with a flexible outer shape, wherein the fluid chamber} contains at least one element displaceably arranged in the fluid chamber, preferably in the form of a plurality of regular or irregular spheres, and a lubricating fluid which fills spaces in the fluid chamber, wherein the lubricating fluid is provided for reducing surface friction between the at least one element and surfaces contacting the at least one element, wherein the lubricating fluid is a thixotropic fluid. T_{he breast implant of any one of aspect 1, at a body temperature of 37 °C and when not exposed to shear stress, the thixotropic fluid} bonds the at least one element to surfaces contacting the at least one element. T_{he breast implant of any one of aspect 1 or 2, comprising 1000 or more of the spheres in the fluid chamber.} _{SE - SIXTH ASPECT: RECESSES FOR LUBRICATION (COMBINABLE WITH ALL OTHER ASPECTS)} _{A breast implant for implantation in a patient’s body or a breast implant system comprising the breast implant, comprising} _{- a first fluid chamber having a flexible outer shape, wherein at least one element is displaceably contained in the first fluid chamber,} and -_{a port in the first fluid chamber configured for supplying a lubricating fluid into the first fluid chamber in order to reduce surface} _{friction between an outer surface of the at least one element and surfaces contacting the outer surface of the at least one element,} _{wherein at least one of an inner surface of the first fluid chamber and the outer surface of the at least one element has one or more} recesses. T_{he breast implant system of aspect 1, wherein at least some of the one or more recesses are provided as one or more grooves.} _{The breast implant system of aspect 2, wherein at least some of the grooves are connected to one or more other ones of the grooves.} _{The breast implant system of aspect 2 or 3, wherein the one or more grooves extend from the port along the inner surface of the first} fluid chamber. T_{he breast implant system of any one of aspects 1 to 4, wherein at least some of the recesses are provided in the form of valleys} _{between elevations.} _{The breast implant system of any one of aspects 1 to 5, wherein the at least one element contained in the fluid chamber comprises 1000} or more regular or irregular spheres. T_{he breast implant system of any one of aspects 1 to 6, wherein a second fluid chamber containing the lubricating fluid is connected to} _{the first fluid chamber so as to allow the lubricating fluid to be supplied from the second fluid chamber through the port to the first} fluid chamber. _{8. The breast implant system of any one of aspects 1 to 6, wherein the port is a self-sealing injection port which is arranged in or on the} first fluid chamber at a location so as to be pierceable, when implanted, with a syringe from outside the breast implant. _{488SE - SEVENTH ASPECT: LUBRICATION INJECTION PORT IN BREAST IMPLANT (COMBINABLE WITH ALL OTHER ASPECTS)} _{1. A breast implant system for implantation in a patient’s body, comprising} _{- a breast implant with a first fluid chamber having a flexible outer shape, wherein at least one element is displaceably contained in} the first fluid chamber, and -_{a port configured for supplying a lubricating fluid into the first fluid chamber in order to reduce surface friction between an outer} surface of the at least one element and surfaces contacting the outer surface of the at least one element, wherein the port is a self-sealing injection port which is arranged in or on the first fluid chamber at a location so as to be pierceable, when implanted in a patient’s breast, with a syringe from outside the breast implant. _{482SE - EIGHTH ASPECT: PIEZOELECTRIC MOTOR AND/OR PUMP (COMBINABLE WITH FIRST TO FOURTH, SIXTH AND SEVENTH ASPECTS)} _{1. A breast implant system, preferably comprising a breast implant system or breast implant of any one of the first to fourth, sixth and} seventh aspects, comprising: -_{a plurality of chambers including a first fluid chamber and a second fluid chamber, said first and second fluid chambers being} _{adapted for implantation in a human body with the first fluid chamber forming part of a breast implant, said first and second fluid} chambers being interconnected when implanted for fluid to be transferred between the first and second fluid chambers so as to change their respective fluid content, and -_{at least one of: at least one piezoelectric motor and at least one piezoelectric pump.} PIEZOELECTRIC MOTOR _{2. The breast implant of aspect 1, wherein the at least one piezoelectric motor is arranged for driving a pump for pumping fluid between} the first and second fluid chambers. _{3. The breast implant of aspect 1 or 2, wherein the at least one piezoelectric motor comprises a piezoelectric inchworm motor.} _{4. The breast implant of aspect 1 or 2, wherein the at least one piezoelectric motor comprises a piezoelectric inertial motor.} _{5. The breast implant of aspect 1 or 2, wherein the at least one piezoelectric motor comprises a piezoelectric walk-drive motor.} _{6. The breast implant of any one of aspects 1 to 5, wherein the piezoelectric motor is a linear piezoelectric motor.} _{7. The breast implant of aspect 6, wherein the linear piezoelectric motor operates with at least one of:} _{- a speed in a range of 1 mm/s to 10 mm/s,} _{- a stroke length in a range of 4 mm – 30 mm, and} _{- a force in a range of 2 N – 30 N.} _{8. The breast implant of any one of aspects 1 to 5, wherein the piezoelectric motor is a rotary piezoelectric motor.} _{9. The breast implant of aspect 8, wherein the rotary piezoelectric motor which operates with at least one of:} _{- a rotational speed in a range of 1 mrad/s – 100 mrad/s, and} _{- a torque in a range of 100 Nmm – 900 Nmm.} _{10. The breast implant of aspect 1 or 2, wherein the at least one piezoelectric motor comprises a piezoelectric ultrasonic motor.} _{11. The breast implant of aspect 10, wherein the piezoelectric ultrasonic motor is a traveling wave ultrasonic motor.} _{12. The breast implant of aspect 10, wherein the piezoelectric ultrasonic motor is a standing wave ultrasonic motor.} _{13. The breast implant of any one of aspects 10 to 12, wherein the piezoelectric ultrasonic motor is a rotary piezoelectric ultrasonic motor} which operates with at least one of: -_{a rotational speed in a range of 10 mrad/s – 10,000 mrad/s, and} _{- a torque in a range of 20 Nmm – 450 Nmm.} _{14. The breast implant of any one of aspects 10 to 12, wherein the piezoelectric ultrasonic motor is a linear piezoelectric ultrasonic motor} which operates with at least one of: -_{a speed in a range of 4 mm/s – 100 mm/s,} _{- a stroke length in a range of 4 mm – 30 mm, and} _{- a force in a range of 0.5 N – 30 N.} _{15. The breast implant of any one of aspects 1 to 14, wherein the at least one piezoelectric motor comprises at least one bimorph} piezoelectric actuator. _{16. The breast implant of any one of aspects 1 to 15, wherein the at least one piezoelectric motor is substantially non-magnetic.} _{17. The breast implant of any one of aspects 1 to 16, wherein the at least one piezoelectric motor is substantially non-metallic.} _{18. The breast implant of any one of aspects 1 to 17, wherein the at least one piezoelectric motor is a reversible piezoelectric motor.} _{19. The breast implant of any one of aspects 1 to 18, wherein the at least one piezoelectric motor forms part of the drive unit.} PIEZOELECTRIC PUMP _{20. The breast implant system of any one of aspects 1 to 19, wherein the at least one piezoelectric pump is configured for pumping fluid} between the first and second fluid chambers. _{21. The breast implant system of aspect 20, wherein the piezoelectric pump comprises a first wall portion, a first diaphragm, a first} chamber and a driving element, wherein -_{the first diaphragm and the first wall portion enclose the first chamber,} _{- the first wall portion comprises an inlet, configured to connect the first chamber to a first inlet reservoir, and an outlet, configured} to connect the first chamber to a first outlet reservoir, -_{the first diaphragm is configured to bend in response to operation of the driving element and} _{- the driving element comprises a piezoelectric actuator or is configured to be operated by a piezoelectric motor.} _{The breast implant system of aspect 21, wherein the inlet of the first wall portion comprises an inlet valve and the outlet of the first} wall portion comprises an outlet valve. _{The breast implant system of aspect22, wherein any of the inlet valve of the first wall portion and outlet valve of the first wall portion} is a check valve or an active valve. _{The breast implant system of aspect 23, wherein the check valve is a ball valve.} _{The breast implant system of aspect 21, wherein the inlet of the first wall portion comprises an inlet static element and the outlet of the} first wall portion comprises an outlet static element, wherein any of the inlet static element and outlet static element is configured to act as a nozzle or a diffuser. _{The breast implant system of any one of aspects 21 to 25, wherein the first diaphragm comprises a first movable wall portion.} _{The breast implant system of aspect 26, wherein the first movable wall portion comprises elevated and lowered portions, wherein the} elevated and lowered portions enable at least one of compression and expansion for moving the first movable wall portion. _{The breast implant system of aspect 27, wherein the first movable wall portion comprises a substantially stiff portion.} _{The breast implant system of any one of aspects 26 to 28, wherein the first movable wall portion comprises a bellows.} _{The breast implant system of aspect 29, wherein the bellows comprises metal.} _{The breast implant system of aspect 30, wherein the bellows comprises at least one of: an oval cross-section, an elliptic cross-section} and a circular cross-section. _{The breast implant system of any one of aspects 21 to 31, wherein the piezoelectric pump further comprises:} _{- an auxiliary wall portion and} _{- an auxiliary chamber sealed from the first chamber,} wherein the auxiliary wall portion and the first diaphragm enclose the auxiliary chamber. _{The breast implant system of any one of aspects 21 to 31, wherein the piezoelectric pump further comprises:} _{- an auxiliary wall portion,} _{- an auxiliary chamber sealed from the first chamber and} _{- an auxiliary diaphragm configured to bend in the same direction as the first diaphragm in response to operation of the driving} element, wherein the auxiliary wall portion and the auxiliary diaphragm enclose the auxiliary chamber. _{The breast implant system of aspect 13 or 14, wherein the auxiliary chamber is configured to be connected to a pressure adapter} enabling variation of pressure in the auxiliary chamber. _{The breast implant system of aspect 15, wherein the pressure adapter comprises an elastic portion having a surface area and wherein} the elastic portion is configured to maintain substantially the same surface area while enabling variation of pressure in the auxiliary chamber. _{The breast implant system of any one of aspects 2 to 12, wherein the piezoelectric pump further comprises a second wall portion, a} second diaphragm and a second chamber, wherein _{- the second diaphragm and the second wall portion enclose the second chamber,} _{- the second wall portion comprises an inlet, configured to connect the second chamber to a second inlet reservoir, and an outlet,} configured to connect the second chamber to a second outlet reservoir, and _{- the second diaphragm is configured to bend in the same direction as the first diaphragm in response to operation of the driving} element. _{The breast implant system of aspect 17, wherein the inlet of the second wall portion comprises an inlet valve and the outlet of the second} wall portion comprises an outlet valve. _{The breast implant system of aspect 18, wherein any of the inlet valve of the second wall portion and outlet valve of the second wall} portion is a check valve or an active valve. _{The breast implant system of aspect 19, wherein the check valve is a ball valve.} _{The breast implant system of aspect 17, wherein the inlet of the second wall portion comprises an inlet static element and the outlet of} _{the second wall portion comprises an outlet static element, wherein any of the inlet static element and outlet static element is} configured to act as a nozzle or a diffuser. _{The breast implant system of any one of aspects 21 to 35, wherein the piezoelectric pump comprises at least two portions connected} _{in series, wherein each portion is a piezoelectric pump of any one of aspects 21 to 35.} _{The breast implant system of any one of aspects 36 to 40, wherein the piezoelectric pump comprises at least two portions connected} _{in series, wherein each portion is a piezoelectric pump of any one of aspects 36 to 40.} _{The breast implant system of any one of aspects 21 to 35, wherein the piezoelectric pump comprises at least two portions connected} _{in parallel, wherein each portion is a piezoelectric pump of any one of aspects 21 to 35.} _{The breast implant system of any one of aspects 36 to 40, wherein the piezoelectric pump comprises at least two portions connected} _{in parallel, wherein each portion is a piezoelectric pump of any one of aspects 36 to 40.} _{The breast implant system of any one of the aspects21 to 44, wherein the breast implant system further comprises a controller} configured to control the piezoelectric pump. _{The breast implant system of aspect 45, comprising a sensor configured to measure a parameter of the piezoelectric pump, and a} feedback unit, wherein: _{- the sensor is further configured to transmit the measured parameter to the feedback unit,} _{- the feedback unit is configured to transmit a conditioning signal to the controller based on the measured parameter received} from the sensor and based on a set value of the parameter, and _{- the controller is configured to adjust the control of the piezoelectric pump based on the conditioning signal received from the} feedback unit in order for the measured parameter to achieve the set value. _{The breast implant system of aspect 46, wherein the parameter of the piezoelectric pump measured by the sensor comprises at least} a flow rate or a pressure. (SUB-)ASPECT: CONTROL UNIT (COMBINABLE WITH FIRST TO FOURTH, SIXTH TO EIGHTH ASPECTS) _{1. The breast implant system of any one of the first to fourth or fifth to eighth aspects, further comprising a control unit adapted to} directly or indirectly control one or more elements of the system. _{2. The breast implant system of aspect 1, wherein the control unit is adapted to control the exchange of fluid between the first and second} fluid chambers. _{3. The breast implant system of aspect 1 or 2, wherein the control unit comprises a first part adapted to cooperate with a second part} _{from outside the patient’s body, wherein the second part is configured for implantation in the patient’s body.} _{483SE - METHOD OF IMPLANTATION (THIRD ASPECT – ENERGY RECEIVER IN STERNUM + MOTOR/PUMP IN BREAST IMPLANT)} _{4. A surgical method of implanting a breast implant system in a patient’s body, comprising the steps of:} _{- cutting an opening in the skin in the breast area,} _{- dissecting the area,} _{- placing at least a part of a breast implant system in the dissected area, wherein the breast implant system comprises:} _{- a plurality of chambers including a first fluid chamber and a second fluid chamber, said first and second fluid chambers} being adapted for implantation in a human body with the first fluid chamber forming part of a breast implant, said first and second fluid chambers being interconnected when implanted for fluid to be transferred between the first and second fluid chambers so as to change their respective fluid content, -_{at least one energy consuming part which forms part of the breast implant and} _{- an energy source for supplying energy to the at least one energy consuming part, wherein the energy source comprises} a wireless energy transmitter configured to wirelessly transmit energy from outside the patient’s body and an energy receiver configured to receive the wirelessly transmitted energy from the wireless energy transmitter, -_{placing the energy receiver above the patient’s sternum and} _{- suturing the skin.} _{5. A surgical method of laparoscopic implantation of a breast implant system in a patient’s body, comprising the steps of:} _{- inserting a needle like tube into the breast area of the patient’s body,} _{- using the needle like tube to fill the breast area with gas thereby expanding a cavity,} _{- advancing at least two laparoscopic trocars in the patient’s body,} _{- inserting a camera through one of the trocars,} _{- inserting at least one dissecting tool through another one of the trocars and dissecting an area of at least one portion of the breast} area of the patient, and _{- placing at least a part of a breast implant system in the dissected area, wherein the breast implant system comprises:} _{- a plurality of chambers including a first fluid chamber and a second fluid chamber, said first and second fluid chambers} being adapted for implantation in a human body with the first fluid chamber forming part of a breast implant, said first and second fluid chambers being interconnected when implanted for fluid to be transferred between the first and second fluid chambers so as to change their respective fluid content, -_{at least one energy consuming part which forms part of the breast implant and} _{- an energy source for supplying energy to the at least one energy consuming part, wherein the energy source comprises} a wireless energy transmitter configured to wirelessly transmit energy from outside the patient’s body and an energy receiver configured to receive the wirelessly transmitted energy from the wireless energy transmitter, and _{- placing the energy receiver above the patient’s sternum.} _{480SE - FIRST METHOD ASPECT: THROTTLED REFLOW} _{1. A method of reshaping an implanted breast implant post-operatively, wherein the breast implant system comprises:} _{- a plurality of chambers including a first fluid chamber (1) and a second fluid chamber (2), said first and second fluid} chambers (1, 2) being adapted for implantation in a human body with the first fluid chamber (1) forming part of a breast implant (_{10), said first and second fluid chambers (1, 2) being interconnected when implanted for fluid to be transferred between the first} and second fluid chambers (1, 2) so as to change their respective fluid content, -_{an energy storage configured to store energy when fluid is transferred between the first and second fluid chambers (1, 2)} and further configured to release the stored energy in a manner so as to re-transfer the transferred fluid between the first and second fluid chambers (1, 2), and -_{a flow control device (24) configured to control fluid transfer between the first and second fluid chambers (1, 2), wherein} the flow control device (24) comprises at least one of: -_{a throttle which is configured to permit throttled re-transfer of the transferred fluid between the first and} second fluid chambers (1, 2) automatically over time, and -_{a piston configured such that fluid transfer between the first and second fluid chambers (1, 2) is realized by} means of movement of the piston (8), wherein friction acting on the piston (8) counteracts the release of the stored energy and is adjusted or adjustable such that re-transfer of the transferred fluid between the first and second fluid c_{hambers (1, 2) occurs automatically over time,} _{wherein the method comprises the step of operating the flow control device (24) so as to transfer fluid between the first and second} fluid chambers (1, 2). _{2. The method of aspect 1, further comprising the step of sending a wireless control signal from outside the patient’s body, wherein the} flow control device (24) is operated in response to the wireless control signal. _{3. The method of aspect 1 or 2, further comprising the step of actuating a subcutaneously implanted actuator (23), wherein the flow} control device (24) is operated in response to such actuation. _{SE - SECOND METHOD ASPECT: REFLOW SWITCH (UNTHROTTLED OR THROTTLED)} _{A method of reshaping an implanted breast implant post-operatively, wherein the breast implant system comprises:} _{- a plurality of chambers including a first fluid chamber (1) and a second fluid chamber (2), said first and second fluid chambers (1,} 2) being adapted for implantation in a human body with the first fluid chamber (1) forming part of a breast implant (10), said first and second fluid chambers (1, 2) being interconnected when implanted for fluid to be transferred between the first and second fluid chambers (1, 2) so as to change their respective fluid content, -_{an energy storage configured to store energy when fluid is transferred between the first and second fluid chambers (1, 2)} and further configured to release the stored energy in a manner so as to re-transfer the transferred fluid between the first and second fluid chambers (1, 2), and -_{a flow control device (24) configured to control fluid transfer between the first and second fluid chambers (1, 2),} wherein the flow control device (24) comprises a switch which is operable so as to switch the flow control device (24) between a first state in which the flow control device (24) is configured to permit free transfer of fluid between the first and second fluid chambers (1, 2) in a first direction while preventing transfer of fluid in a second direction opposite to the first direction and a second state in which the flow control device (24) is configured to permit re-transfer of the transferred fluid between the first and second fluid chambers (1, 2) in the second direction, wherein the method comprises the step of operating the switch so as to switch the flow control device (24) between the first state and the second state. T_{he method of aspect 1, further comprising the step of sending a wireless control signal from outside the patient’s body, wherein the} switch is operated in response to the wireless control signal. T_{he method of aspect 1 or 2, further comprising the step of actuating a subcutaneously implanted actuator (23), wherein the switch is} operated in response to such actuation. _{SE - THIRD METHOD ASPECT: ENERGY RECEIVER IN STERNUM + MOTOR/PUMP IN BREAST IMPLANT} _{A method of reshaping an implanted breast implant post-operatively, wherein the breast implant system comprises:} _{- a plurality of chambers including a first fluid chamber (1) and a second fluid chamber (2), said first and second fluid} chambers (1, 2) being adapted for implantation in a human body with the first fluid chamber (1) forming part of a breast implant (10), said first and second fluid chambers (1, 2) being interconnected when implanted for fluid to be transferred between the first and second fluid chambers (1, 2) so as to change their respective fluid, -_{at least one energy consuming part which forms part of the breast implant (10) and} _{- an energy source for supplying energy to the at least one energy consuming part, wherein the energy source comprises} a wireless energy transmitter configured to wirelessly transmit energy from outside the patient’s body and one or more than one energy receiver (29) configured to receive the wirelessly transmitted energy from the wireless energy transmitter, wherein the one or more than one energy receiver (29) is implanted within the patient’s body above the patient’s sternum (S), and wherein the method comprises the step of wirelessly transmitting energy to the energy source from outside the patient’s body via the one or more than one energy receiver (29). T_{he method of aspect 1, further comprising the step of sending a wireless control signal from outside the patient’s body, wherein¸ in} _{response to the wireless control signal, fluid is transferred between the first and second fluid chambers (1, 2) so as to change their} respective fluid. T_{he method of aspect 1 or 2, further comprising the step of actuating a subcutaneously implanted actuator (23), wherein¸ in response} _{to such actuation, fluid is transferred between the first and second fluid chambers (1, 2) so as to change their respective fluid.} _{SE - EIGHTH METHOD ASPECT: PIEZOELECTRIC MOTOR AND/OR PUMP} _{A method of reshaping an implanted breast implant post-operatively, wherein the breast implant system comprises:} _{- a plurality of chambers including a first fluid chamber (1) and a second fluid chamber (2), said first and second fluid chambers} _{(1, 2) being adapted for implantation in a human body with the first fluid chamber (1) forming part of a breast implant (10), said} first and second fluid chambers (1, 2) being interconnected when implanted for fluid to be transferred between the first and second fluid chambers (1, 2) so as to change their respective fluid content, and -_{at least one of: at least one piezoelectric motor (MO) and at least one piezoelectric pump (P),} wherein the method comprises the step of using at least one of the at least one piezoelectric motor (MO) and piezoelectric pump (P) for transferring fluid between the first and second fluid chambers (1, 2) so as to change their respective fluid content. T_{he method of aspect 1, further comprising the step of sending a wireless control signal from outside the patient’s body, wherein at} least one of the piezoelectric motor (MO) and piezoelectric pump (P) is operated in response to the wireless control signal. T_{he method of aspect 1 or 2, further comprising the step of actuating a subcutaneously implanted actuator (23), wherein at least one} of the piezoelectric motor (MO) and piezoelectric pump (P) is operated in response to such actuation.

Claims

CLAIMS 1_{. A breast implant system, comprising:} _{- a plurality of chambers including a first fluid chamber (1) and a second fluid chamber (2), said first and second fluid chambers (1,} _{2) being adapted for implantation in a human body with the first fluid chamber (1) forming part of a breast implant (10), said first and} second fluid chambers (1, 2) being interconnected when implanted for fluid to be transferred between the first and second fluid chambers (1, 2) so as to change their respective fluid content, -_{an energy storage configured to store energy when fluid is transferred between the first and second fluid chambers (1, 2) and} further configured to release the stored energy in a manner so as to re-transfer the transferred fluid between the first and second fluid chambers (1, 2), and -_{a flow control device (24) configured to control fluid transfer between the first and second fluid chambers (1, 2), wherein the flow} control device (24) comprises at least one of: -_{a throttle which is configured to permit throttled re-transfer of the transferred fluid between the first and} second fluid chambers (1, 2) automatically over time, and -_{a piston configured such that fluid transfer between the first and second fluid chambers (1, 2) is realized by} means of movement of the piston (8), wherein friction acting on the piston (8) counteracts the release of the stored energy and is adjusted or adjustable such that re-transfer of the transferred fluid between the first and second fluid chambers (1, 2) occurs automatically over time. _{2. The breast implant system of claim 1, wherein the flow control device (24) comprising the throttle further comprises a check valve} which is configured to permit free transfer of fluid between the first and second fluid chambers (1, 2) and prevent re-transfer of the transferred fluid through the check valve. _{3. The breast implant system of claim 1, wherein the flow control device (24) comprising the piston (8) further comprises a cylinder (5)} arranged between the first and second fluid chambers (1, 2), wherein the piston (8) is movably arranged in the cylinder (5) such that fluid transfer between the first and second fluid chambers (1, 2) is realized by means of movement of the piston (8) in the cylinder (5) causing a fluid transfer from the first fluid chamber (1) to the cylinder (5) and from the cylinder (5) to the second fluid chamber (2), and vice versa. _{4. The breast implant system of any one of claims 1 to 3, wherein the energy storage, which is configured to store energy when fluid is} transferred between the first and second fluid chambers (1, 2), comprises an elastic wall which surrounds one of the first and second fluid chambers (1, 2) at least partly, wherein the elastic wall is configured to expand when fluid is transferred from the respective other one of the first and second fluid chambers (1, 2) into said one of the first and second fluid chambers (1, 2). _{5. The breast implant system of any one of claims 1 to 4, wherein the energy storage configured to store energy when fluid is transferred} between the first and second fluid chambers (1, 2) comprises a resilient element (25), wherein the resilient element (25) is configured to expand one of the first and second fluid chambers (1, 2). _{6. The breast implant system of claim 5, wherein the resilient element (25) is configured to expand the second fluid chamber (2).} _{7. The breast implant system of claim 5 or 6, wherein the resilient element (25) comprises a spring.}

_{8. The breast implant system of any one of claims 1 to 7, comprising at least one element (21) which is displaceably contained in the first} fluid chamber (1), wherein the second fluid chamber (2) comprises a lubricating fluid so as to allow lubricating fluid to be supplied from t_{he second fluid chamber (2) to the first fluid chamber (1) in order to reduce surface friction between an outer surface of said at least} one element (21) and surfaces contacting the outer surface of said at least one element (21). _{9. The breast implant system of any one of claims 1 to 8, wherein the second fluid chamber (2) is adapted for implantation within the} human body remote from the breast implant (10) so as to form a reservoir for the first fluid chamber (1), the system further comprising a_{t least one conduit (19) between the remotely implantable second fluid chamber (2) and the first fluid chamber (1) for fluid exchange} between the first and second fluid chambers (1, 2). _{10. The breast implant system of any one of claims 1 to 9, wherein the second fluid chamber (2) forms part of the breast implant (10) along} with the first fluid chamber (1). _{11. The breast implant system of claim 10, wherein the breast implant (10) has a constant volume and a variable shape, the shape being} variable upon fluid exchange between the first and second fluid chambers (1, 2). _{12. The breast implant system of any one of claims 1 to 11, comprising a third fluid chamber (14), wherein:} _{- the second fluid chamber (2) forms part of the breast implant (10) along with the first fluid chamber (1),} _{- the first and second fluid chambers (1, 2) comprise an incompressible fluid,} _{- the third fluid chamber (14) forms also part of the breast implant (10),} _{- the third fluid chamber (14) comprises a compressible fluid, and} _{- an exchange of the incompressible fluid between the first and second fluid chambers (1, 2) results in an increase of pressure of} the compressible fluid within the third fluid chamber (14), wherein the increase of pressure within the third fluid chamber (14) constitutes the energy storage. _{13. The breast implant system of any one of claims 1 to 12, wherein the exchange of an amount of fluid between the first and second fluid} chambers (1, 2) involves a movement of an amount of fluid in at least one third fluid chamber which is different to the amount of fluid e_{xchanged between the first and second fluid chambers (1, 2).} _{14. The breast implant system of claim 13, wherein the at least one third fluid chamber comprises sub-chambers and wherein at least one} of said first and second fluid chambers (1, 2) is operatively connected to at least one of the sub-chambers and is adapted to expand or contract said sub-chamber when fluid is exchanged between the first and second fluid chambers (1, 2), the sub-chambers being interconnected so as to allow fluid to flow into the expanded, or from the contracted, sub-chamber when fluid is exchanged between the first and second fluid chambers (1, 2). _{15. The breast implant system of claim 13 or 14, wherein at least one of the sub-chambers of the third fluid chamber is configured for being} implanted subcutaneously such that fluid can be exchanged between the sub-chambers by manually compressing the subcutaneously implantable sub-chamber. _{16. The breast implant system of any one of claims 13 to 15, wherein a resilient element (25) is provided for urging the third fluid chamber} or at least one of the sub-chambers into a state of minimum or maximum volume.

_{17. The breast implant system of any one of claims 1 to 16, comprising:} _{- at least one energy consuming part which forms part of the breast implant (10) and} _{- an energy source for supplying energy to the at least one energy consuming part, wherein the energy source comprises a wireless} energy transmitter configured to wirelessly transmit energy from outside the patient’s body and one or more than one energy receiver (29) configured to receive the wirelessly transmitted energy from the wireless energy transmitter, wherein the one or more than one energy receiver (29) is configured for implantation within the patient’s body above the patient’s sternum (S). _{18. The breast implant system of claim 17, wherein the breast implant (10) has a rigid back wall (3) configured for being placed adjacent} the patient’s thorax, wherein the energy consuming part is contained in or on the back wall (3). _{19. The breast implant system of claim 17 or 18, wherein the energy consuming part comprises at least one of a motor (M) and a pump (P).} _{20. The breast implant system of any one of claims 17 to 19, wherein the energy source comprises an energy storage (E) connected to the} energy consuming part for storing the wirelessly transmitted energy. _{21. The breast implant system of any one of claims 17 to 20, wherein the energy source comprises an implantable energy transforming} device for transforming the wirelessly transmitted energy into electric energy for direct use by the energy consuming part. _{22. The breast implant system of any one of claims 1 to 21, comprising} _{- at least one element (21) displaceably contained in the first fluid chamber (1), and} _{- a port (31) in the first fluid chamber (1) configured for supplying a lubricating fluid into the first fluid chamber (1) in order to reduce} surface friction between an outer surface of the at least one element (21) and surfaces contacting the outer surface of the at least one element (21), wherein at least one of an inner surface of the first fluid chamber (1) and the outer surface of the at least one element (21) has one or more recesses. _{23. The breast implant system of claim 22, wherein at least some of the one or more recesses are provided as one or more grooves.} _{24. The breast implant system of claim 23, wherein at least some of the grooves are connected to one or more other ones of the grooves.} _{25. The breast implant system of claim 23 or 24, wherein the one or more grooves extend from the port (31) along the inner surface of the} first fluid chamber (1). _{26. The breast implant system of any one of claims 23 to 25, wherein at least some of the recesses are provided in the form of valleys} between elevations. _{27. The breast implant system of any one of claims 22 to 26, wherein the at least one element (21) contained in the fluid chamber comprises} 1000 or more regular or irregular spheres. _{28. The breast implant system of any one of claims 22 to 27, wherein a second fluid chamber (2) containing the lubricating fluid is connected} to the first fluid chamber (1) so as to allow the lubricating fluid to be supplied from the second fluid chamber (2) through the port (31) to the first fluid chamber (1).

_{29. The breast implant system of any one of claims 22 to 28, wherein the port (31) is a self-sealing injection port which is arranged in or} on the first fluid chamber (1) at a location so as to be pierceable, when implanted, with a syringe from outside the breast implant (10). _{30. The breast implant system of any one of claims 1 to 28, comprising} _{- at least one element (21) displaceably contained in the first fluid chamber (1), and} _{- a port (31) configured for supplying a lubricating fluid into the first fluid chamber (1) in order to reduce surface friction between} an outer surface of the at least one element (21) and surfaces contacting the outer surface of the at least one element (21), wherein the port (31) is a self-sealing injection port which is arranged in or on the first fluid chamber (1) at a location so as to be pierceable, when implanted in a patient’s breast, with a syringe from outside the breast implant (10). _{31. The breast implant system of any one of claims 1 to 30, comprising at least one of: at least one piezoelectric motor (MO) and at least} one piezoelectric pump (P). _{32. The breast implant system of claim 31, wherein the at least one piezoelectric motor (MO) is arranged for driving a pump (P) for pumping} fluid between the first and second fluid chambers (1, 2). _{33. The breast implant system of claim 31 or 32, wherein the at least one piezoelectric motor (MO) comprises a piezoelectric inchworm} motor. _{34. The breast implant system of claim 31 or 32, wherein the at least one piezoelectric motor (MO) comprises a piezoelectric inertial motor.} _{35. The breast implant system of claim 31 or 32, wherein the at least one piezoelectric motor (MO) comprises a piezoelectric walk-drive} motor. _{36. The breast implant system of any one of claims 31 to 35, wherein the piezoelectric motor (MO) is a linear piezoelectric motor.} _{37. The breast implant system of claim 36, wherein the linear piezoelectric motor operates with at least one of:} _{- a speed in a range of 1 mm/s to 10 mm/s,} _{- a stroke length in a range of 4 mm – 30 mm, and} _{- a force in a range of 2 N – 30 N.} _{38. The breast implant system of any one of claims 31 to 35, wherein the piezoelectric motor (MO) is a rotary piezoelectric motor.} _{39. The breast implant system of claim 38, wherein the rotary piezoelectric motor which operates with at least one of:} _{- a rotational speed in a range of 1 mrad/s – 100 mrad/s, and} _{- a torque in a range of 100 Nmm – 900 Nmm.} _{40. The breast implant system of claim 31 or 32, wherein the at least one piezoelectric motor (MO) comprises a piezoelectric ultrasonic} motor. _{41. The breast implant system of claim 40, wherein the piezoelectric ultrasonic motor is a traveling wave ultrasonic motor.} _{42. The breast implant system of claim 41, wherein the piezoelectric ultrasonic motor is a standing wave ultrasonic motor.}

_{43. The breast implant system of any one of claims 40 to 42, wherein the piezoelectric ultrasonic motor is a rotary piezoelectric ultrasonic} motor which operates with at least one of: -_{a rotational speed in a range of 10 mrad/s – 10,000 mrad/s, and} _{- a torque in a range of 20 Nmm – 450 Nmm.} _{44. The breast implant system of any one of claims 40 to 42, wherein the piezoelectric ultrasonic motor is a linear piezoelectric ultrasonic} motor which operates with at least one of: -_{a speed in a range of 4 mm/s – 100 mm/s,} _{- a stroke length in a range of 4 mm – 30 mm, and} _{- a force in a range of 0.5 N – 30 N.} _{45. The breast implant system of any one of claims 31 to 44, wherein the at least one piezoelectric motor (MO) comprises at least one} bimorph piezoelectric actuator. _{46. The breast implant system of any one of claims 31 to 45, wherein the at least one piezoelectric motor (MO) is substantially non-magnetic.} _{47. The breast implant system of any one of claims 31 to 46, wherein the at least one piezoelectric motor (MO) is substantially non-metallic.} _{48. The breast implant system of any one of claims 31 to 47, wherein the at least one piezoelectric motor (MO) is a reversible piezoelectric} motor. _{49. The breast implant system of any one of claims 31 to 48, wherein the at least one piezoelectric motor (MO) forms part of the drive unit.} _{50. The breast implant system of any one of claims 31 to 49, wherein the at least one piezoelectric pump (P) is configured for pumping fluid} between the first and second fluid chambers (1, 2). _{51. The breast implant system of claim 50, wherein the piezoelectric pump (P) comprises a first wall portion, a first diaphragm, a first} chamber and a driving element, wherein -_{the first diaphragm and the first wall portion enclose the first chamber,} _{- the first wall portion comprises an inlet, configured to connect the first chamber to a first inlet reservoir, and an outlet, configured} to connect the first chamber to a first outlet reservoir, -_{the first diaphragm is configured to bend in response to operation of the driving element and} _{- the driving element comprises a piezoelectric actuator or is configured to be operated by a piezoelectric motor (MO).} _{52. The breast implant system of claim 51, wherein the inlet of the first wall portion comprises an inlet valve and the outlet of the first wall} portion comprises an outlet valve. _{53. The breast implant system of claim 52, wherein any of the inlet valve of the first wall portion and outlet valve of the first wall portion is} a check valve or an active valve. _{54. The breast implant system of claim 53, wherein the check valve is a ball valve.} _{55. The breast implant system of claim 51, wherein the inlet of the first wall portion comprises an inlet static element and the outlet of the} first wall portion comprises an outlet static element, wherein any of the inlet static element and outlet static element is configured to act as a nozzle or a diffuser.

_{56. The breast implant system of any one of claims 51 to 55, wherein the first diaphragm comprises a first movable wall portion.} _{57. The breast implant system of claim 56, wherein the first movable wall portion comprises elevated and lowered portions, wherein the} _{elevated and lowered portions enable at least one of compression and expansion for moving the first movable wall portion.} _{58. The breast implant system of claim 57, wherein the first movable wall portion comprises a substantially stiff portion.} _{59. The breast implant system of any one of claims 56 to 58, wherein the first movable wall portion comprises a bellows.} _{60. The breast implant system of claim 59, wherein the bellows comprises metal.} _{61. The breast implant system of claim 60, wherein the bellows comprises at least one of: an oval cross-section, an elliptic cross-section} and a circular cross-section. _{62. The breast implant system of any one of claims 51 to 61, wherein the piezoelectric pump (P) further comprises:} _{- an auxiliary wall portion and} _{- an auxiliary chamber sealed from the first chamber,} wherein the auxiliary wall portion and the first diaphragm enclose the auxiliary chamber. _{63. The breast implant system of any one of claims 51 to 61, wherein the piezoelectric pump (P) further comprises:} _{- an auxiliary wall portion,} _{- an auxiliary chamber sealed from the first chamber and} _{- an auxiliary diaphragm configured to bend in the same direction as the first diaphragm in response to operation of the driving} element, wherein the auxiliary wall portion and the auxiliary diaphragm enclose the auxiliary chamber. _{64. The breast implant system of claim 52 or 53, wherein the auxiliary chamber is configured to be connected to a pressure adapter} enabling variation of pressure in the auxiliary chamber. _{65. The breast implant system of claim 54, wherein the pressure adapter comprises an elastic portion having a surface area and wherein} the elastic portion is configured to maintain substantially the same surface area while enabling variation of pressure in the auxiliary chamber. _{66. The breast implant system of any one of claims 51 to 61, wherein the piezoelectric pump (P) further comprises a second wall portion, a} second diaphragm and a second chamber, wherein -_{the second diaphragm and the second wall portion enclose the second chamber,} _{- the second wall portion comprises an inlet, configured to connect the second chamber to a second inlet reservoir, and an outlet,} configured to connect the second chamber to a second outlet reservoir, and -_{the second diaphragm is configured to bend in the same direction as the first diaphragm in response to operation of the driving} element. _{67. The breast implant system of claim 66, wherein the inlet of the second wall portion comprises an inlet valve and the outlet of the second} wall portion comprises an outlet valve.

_{68. The breast implant system of claim 66, wherein any of the inlet valve of the second wall portion and outlet valve of the second wall} portion is a check valve or an active valve. _{69. The breast implant system of claim 68, wherein the check valve is a ball valve.} _{70. The breast implant system of claim 66, wherein the inlet of the second wall portion comprises an inlet static element and the outlet of} the second wall portion comprises an outlet static element, wherein any of the inlet static element and outlet static element is configured to act as a nozzle or a diffuser. _{71. The breast implant system of any one of claims 51 to 65, wherein the piezoelectric pump (P) comprises at least two portions connected} in series, wherein each portion is a piezoelectric pump (P) of any one of claims 51 to 65. _{72. The breast implant system of any one of claims 66 to 70, wherein the piezoelectric pump (P) comprises at least two portions connected} in series, wherein each portion is a piezoelectric pump (P) of any one of claims 66 to 70. _{73. The breast implant system of any one of claims 51 to 65, wherein the piezoelectric pump (P) comprises at least two portions connected} in parallel, wherein each portion is a piezoelectric pump (P) of any one of claims 51 to 65. _{74. The breast implant system of any one of claims 66 to 70, wherein the piezoelectric pump (P) comprises at least two portions connected} in parallel, wherein each portion is a piezoelectric pump (P) of any one of claims 66 to 70. _{75. The breast implant system of any one of the claims 51 to 74, wherein the breast implant system further comprises a controller} configured to control the piezoelectric pump (P). _{76. The breast implant system of claim 75, comprising a sensor configured to measure a parameter of the piezoelectric pump (P), and a} feedback unit, wherein: -_{the sensor is further configured to transmit the measured parameter to the feedback unit,} _{- the feedback unit is configured to transmit a conditioning signal to the controller based on the measured parameter received} from the sensor and based on a set value of the parameter, and -_{the controller is configured to adjust the control of the piezoelectric pump (P) based on the conditioning signal received from the} feedback unit in order for the measured parameter to achieve the set value. _{77. The breast implant system of claim 76, wherein the parameter of the piezoelectric pump (P) measured by the sensor comprises at} least a flow rate or a pressure. _{78. The breast implant system of any one of claims 1 to 77, further comprising a control unit (C1, C2) adapted to directly or indirectly control} one or more elements of the system. _{79. The breast implant system of claim 78, wherein the control unit (C1, C2) is adapted to control the exchange of fluid between the first} and second fluid chambers (1, 2). _{80. The breast implant system of claim 78 or 79, wherein the control unit (C1, C2) comprises a first part (C1) adapted to cooperate with a} second part (C2) from outside the patient’s body, wherein the second part (C2) is configured for implantation in the patient’s body. _{81. A method of reshaping an implanted breast implant post-operatively, wherein the breast implant system comprises:} _{- a plurality of chambers including a first fluid chamber (1) and a second fluid chamber (2), said first and second fluid} chambers (1, 2) being adapted for implantation in a human body with the first fluid chamber (1) forming part of a breast implant (10), said first and second fluid chambers (1, 2) being interconnected when implanted for fluid to be transferred between the first and second fluid chambers (1, 2) so as to change their respective fluid content, -_{an energy storage configured to store energy when fluid is transferred between the first and second fluid chambers (1, 2)} and further configured to release the stored energy in a manner so as to re-transfer the transferred fluid between the first and second fluid chambers (1, 2), and -_{a flow control device (24) configured to control fluid transfer between the first and second fluid chambers (1, 2), wherein} the flow control device (24) comprises at least one of: -_{a throttle which is configured to permit throttled re-transfer of the transferred fluid between the first and} second fluid chambers (1, 2) automatically over time, and -_{a piston configured such that fluid transfer between the first and second fluid chambers (1, 2) is realized by} means of movement of the piston (8), wherein friction acting on the piston (8) counteracts the release of the stored energy and is adjusted or adjustable such that re-transfer of the transferred fluid between the first and second fluid chambers (1, 2) occurs automatically over time, w_{herein the method comprises the step of operating the flow control device (24) so as to transfer fluid between the first and second} fluid chambers (1, 2). _{82. The method of claim 81, further comprising the step of sending a wireless control signal from outside the patient’s body, wherein the} flow control device (24) is operated in response to the wireless control signal. _{83. The method of claim 81, further comprising the step of actuating a subcutaneously implanted actuator (23), wherein the flow control} device (24) is operated in response to such actuation. _{84. A breast implant system, comprising:} _{- a plurality of chambers including a first fluid chamber (1) and a second fluid chamber (2), said first and second fluid chambers (1,} 2) being adapted for implantation in a human body with the first fluid chamber (1) forming part of a breast implant (10), said first and second fluid chambers (1, 2) being interconnected when implanted for fluid to be transferred between the first and second fluid chambers (1, 2) so as to change their respective fluid content, -_{an energy storage configured to store energy when fluid is transferred between the first and second fluid chambers (1, 2) and} further configured to release the stored energy in a manner so as to re-transfer the transferred fluid between the first and second fluid chambers (1, 2), and -_{a flow control device (24) configured to control fluid transfer between the first and second fluid chambers (1, 2),} wherein the flow control device (24) comprises a switch which is operable so as to switch the flow control device (24) between a first state in which the flow control device (24) is configured to permit free transfer of fluid between the first and second fluid chambers (1, 2) in a first direction while preventing transfer of fluid in a second direction opposite to the first direction and a second state in which the flow control device (24) is configured to permit re-transfer of the transferred fluid between the first and second fluid chambers (1, 2) in the second direction.

_{85. A method of reshaping an implanted breast implant post-operatively, wherein the breast implant system comprises:} _{- a plurality of chambers including a first fluid chamber (1) and a second fluid chamber (2), said first and second fluid chambers (1,} 2) being adapted for implantation in a human body with the first fluid chamber (1) forming part of a breast implant (10), said first and second fluid chambers (1, 2) being interconnected when implanted for fluid to be transferred between the first and second fluid chambers (1, 2) so as to change their respective fluid content, -_{an energy storage configured to store energy when fluid is transferred between the first and second fluid chambers (1, 2)} and further configured to release the stored energy in a manner so as to re-transfer the transferred fluid between the first and second fluid chambers (1, 2), and -_{a flow control device (24) configured to control fluid transfer between the first and second fluid chambers (1, 2),} wherein the flow control device (24) comprises a switch which is operable so as to switch the flow control device (24) between a_{first state in which the flow control device (24) is configured to permit free transfer of fluid between the first and second fluid} _{chambers (1, 2) in a first direction while preventing transfer of fluid in a second direction opposite to the first direction and a} second state in which the flow control device (24) is configured to permit re-transfer of the transferred fluid between the first and second fluid chambers (1, 2) in the second direction, wherein the method comprises the step of operating the switch so as to switch the flow control device (24) between the first state and the second state. _{86. The method of claim 85, further comprising the step of sending a wireless control signal from outside the patient’s body, wherein the} switch is operated in response to the wireless control signal. _{87. The method of claim 85, further comprising the step of actuating a subcutaneously implanted actuator (23), wherein the switch is} operated in response to such actuation. _{88. A breast implant system, comprising:} _{- a plurality of chambers including a first fluid chamber (1) and a second fluid chamber (2), said first and second fluid chambers (1,} 2) being adapted for implantation in a human body with the first fluid chamber (1) forming part of a breast implant (10), said first and second fluid chambers (1, 2) being interconnected when implanted for fluid to be transferred between the first and second fluid chambers (1, 2) so as to change their respective fluid content, -_{at least one energy consuming part which forms part of the breast implant (10) and} _{- an energy source for supplying energy to the at least one energy consuming part, wherein the energy source comprises a wireless} energy transmitter configured to wirelessly transmit energy from outside the patient’s body and one or more than one energy receiver (29) configured to receive the wirelessly transmitted energy from the wireless energy transmitter, wherein the one or more than one energy receiver (29) is configured for implantation within the patient’s body above the patient’s sternum (S). _{89. A method of reshaping an implanted breast implant post-operatively, wherein the breast implant system comprises:} _{- a plurality of chambers including a first fluid chamber (1) and a second fluid chamber (2), said first and second fluid} chambers (1, 2) being adapted for implantation in a human body with the first fluid chamber (1) forming part of a breast implant (10), said first and second fluid chambers (1, 2) being interconnected when implanted for fluid to be transferred between the first and second fluid chambers (1, 2) so as to change their respective fluid, -_{at least one energy consuming part which forms part of the breast implant (10) and} _{- an energy source for supplying energy to the at least one energy consuming part, wherein the energy source comprises} a wireless energy transmitter configured to wirelessly transmit energy from outside the patient’s body and one or more than one energy receiver (29) configured to receive the wirelessly transmitted energy from the wireless energy transmitter, w_{herein the one or more than one energy receiver (29) is implanted within the patient’s body above the patient’s sternum (S), and} wherein the method comprises the step of wirelessly transmitting energy to the energy source from outside the patient’s body via the one or more than one energy receiver (29). _{90. The method of claim 89, further comprising the step of sending a wireless control signal from outside the patient’s body, wherein¸ in} _{response to the wireless control signal, fluid is transferred between the first and second fluid chambers (1, 2) so as to change their} respective fluid. _{91. The method of claim 89, further comprising the step of actuating a subcutaneously implanted actuator (23), wherein¸ in response to} _{such actuation, fluid is transferred between the first and second fluid chambers (1, 2) so as to change their respective fluid.} _{92. A breast implant (10) for implantation in a patient’s body, comprising at least one fluid chamber with a flexible outer shape and a filling} in the fluid chamber, wherein the filling comprises at least one of: -_{a Bingham fluid which behaves, at a normal body temperature of 37 °C, as a rigid body at stresses below a yield stress and starts} to flow at stresses exceeding the yield stress, wherein the yield stress of the Bingham fluid is preferably such that, on the one hand, t_{he Bingham fluid does not flow under its own weight and, on the other hand, the Bingham fluid is configured to flow when the fluid} _{chamber is manually compressed and deformed from outside the breast implant (10) so that the shape of the breast implant (10) can} be changed post-operatively by manually compressing the breast implant (10) and remains in the changed shape unless forces exceeding gravitational forces act on the breast implant (10), -_{a viscoelastic material which exhibits both viscous and elastic characteristics, wherein the breast implant (10) has a predetermined} shape defined by the viscoelastic material of the filling in the fluid chamber, wherein, when the breast implant (10) is deformed so that the predetermined shape of the breast implant (10) changes, the breast implant (10) does not immediately return to its predetermined shape, due to the viscosity of the material, and returns to the predetermined shape over time due to the elasticity of the material, and -_{a memory foam.} _{93. A breast implant (10) for implantation in a patient’s body, comprising a fluid chamber with a flexible outer shape, wherein the fluid} _{chamber contains at least one element (21) displaceably arranged in the fluid chamber, preferably in the form of a plurality of regular} or irregular spheres, and a lubricating fluid which fills spaces in the fluid chamber, wherein the lubricating fluid is provided for reducing surface friction between the at least one element (21) and surfaces contacting the at least one element (21), wherein the lubricating fluid is a thixotropic fluid. _{94. A breast implant (10) for implantation in a patient’s body or a breast implant system comprising the breast implant (10), comprising} _{- a first fluid chamber (1) having a flexible outer shape, wherein at least one element (21) is displaceably contained in the first fluid} chamber (1), and -_{a port (31) in the first fluid chamber (1) configured for supplying a lubricating fluid into the first fluid chamber (1) in order to reduce} surface friction between an outer surface of the at least one element (21) and surfaces contacting the outer surface of the at least one element (21), wherein at least one of an inner surface of the first fluid chamber (1) and the outer surface of the at least one element (21) has one or more recesses. _{95. A breast implant system for implantation in a patient’s body, comprising} _{- a breast implant (10) with a first fluid chamber (1) having a flexible outer shape, wherein at least one element (21) is displaceably} contained in the first fluid chamber (1), and -_{a port (31) configured for supplying a lubricating fluid into the first fluid chamber (1) in order to reduce surface friction between} an outer surface of the at least one element (21) and surfaces contacting the outer surface of the at least one element (21), wherein the port (31) is a self-sealing injection port which is arranged in or on the first fluid chamber (1) at a location so as to be pierceable, when implanted in a patient’s breast, with a syringe from outside the breast implant (10). _{96. A breast implant system, comprising:} _{- a plurality of chambers including a first fluid chamber (1) and a second fluid chamber (2), said first and second fluid chambers (1,} 2) being adapted for implantation in a human body with the first fluid chamber (1) forming part of a breast implant (10), said first and second fluid chambers (1, 2) being interconnected when implanted for fluid to be transferred between the first and second fluid chambers (1, 2) so as to change their respective fluid content, and -_{at least one of: at least one piezoelectric motor (MO) and at least one piezoelectric pump (P).} _{97. A method of reshaping an implanted breast implant post-operatively, wherein the breast implant system comprises:} _{- a plurality of chambers including a first fluid chamber (1) and a second fluid chamber (2), said first and second fluid chambers} _{(1, 2) being adapted for implantation in a human body with the first fluid chamber (1) forming part of a breast implant (10), said} first and second fluid chambers (1, 2) being interconnected when implanted for fluid to be transferred between the first and second fluid chambers (1, 2) so as to change their respective fluid content, and -_{at least one of: at least one piezoelectric motor (MO) and at least one piezoelectric pump (P),} wherein the method comprises the step of using at least one of the at least one piezoelectric motor (MO) and piezoelectric pump (P) for transferring fluid between the first and second fluid chambers (1, 2) so as to change their respective fluid content. _{98. The method of claim 97, further comprising the step of sending a wireless control signal from outside the patient’s body, wherein at} least one of the piezoelectric motor (MO) and piezoelectric pump (P) is operated in response to the wireless control signal. _{99. The method of claim 97, further comprising the step of actuating a subcutaneously implanted actuator (23), wherein at least one of the} piezoelectric motor (MO) and piezoelectric pump (P) is operated in response to such actuation.