NL2013213B1

NL2013213B1 - An electrical connection assembly for a medical implant and a method of providing an electrical connection between a thin film and a connector for a medical implant.

Info

Publication number: NL2013213B1
Application number: NL2013213A
Authority: NL
Inventors: Franciscus Donker Marcus; Reinier Jacobs Egbertus; Wilhelmus Weekamp Johannes
Original assignee: Sapiens Steering Brain Stimulation Bv
Priority date: 2014-07-18
Filing date: 2014-07-18
Publication date: 2016-07-14

Abstract

The present invention relates to an electrical connection assembly (320) for a medical implant, especially for a medical implant for neurostimulation, comprising a thin film (301) and a connector (322), wherein the thin film (301) comprises at least one connector electrode (305), wherein the connector electrode (305) has at least one hole (326), and wherein the connector (322) comprises at least one contact and wherein the hole (326) of the connector electrode (305) is placed above the contact of the connector (322) and the hole (326) and the contact are contacted by means of conductive glue (328). Furthermore, the present invention relates to a method of providing an electrical connection between a thin film (301) and a connector for a medical implant, especially for a medical implant for neurostimulation.

Description

An electrical connection assembly for a medical implant and a method of providing an electrical connection between a thin film and a connector for a medical implant

The present invention relates to an electrical connection assembly for a medical implant, especially for a medical implant for neurostimulation, comprising a thin film and a connector, and method of providing an electrical connection between a thin film and a connector for a medical implant, especially for a medical implant for neurostimulation.

Implantable neurostimulation devices have been used for the past ten years to treat acute or chronic neurological conditions. Deep brain stimulation (DBS), the mild electrical stimulation of sub-cortical structures, belongs to this category of implantable devices, and has been shown to be therapeutically effective for Parkinson’s disease, Dystonia, and Tremor. New applications of DBS in the domain of psychiatric disorders (obsessive compulsive disorder, depression) are being researched and show promising results. In existing systems, the probes are connected to an implantable current pulse generator.

Currently, systems are under development with more, smaller electrodes in a technology based on thin film manufacturing. These novel systems consist of a lead made from a thin film based on thin film technology, as e.g. described in WO 2010/055453 A1. The thin film leads are fixed on a core material to form a lead. These probes will have multiple electrode areas and will enhance the precision to address the appropriate target in the brain and relax the specification of positioning. Meanwhile, undesired side effects due to undesired stimulation of neighbouring areas can be minimized.

Leads that are based on thin film manufacturing are e.g. described by US 7,941,202 and have been used in research products in animal studies. In existing systems, the DBS lead has e.g. four 1.5 mm-wide cylindrical electrodes at the distal end spaced by 0.5 mm or 1.5 mm. The diameter of the lead is 1.27 mm and the metal used for the electrodes and the interconnect wires is an alloy of platinum and iridium. The coiled interconnect wires are insulated individually by fluoropolymer coating and protected in an 80 micron urethane tubing. With such electrode design, the current distribution emanates uniformly around the circumference of the electrode, which leads to stimulation of all areas surrounding the electrode.

To provide a MRI compatible electrode array with a plurality of electrodes e.g. for Deep Brain Stimulation, a thin film substrate with tracks running within a small strip and broadened electrode pads at both ends of the strip is partially wrapped around a tube. The connecting electrode pad at the distal end is connected to the driving electronics of the lead. The thin film substrate is very vulnerable and the handling of this fragile structure is generally not easy.

The electrical and mechanical connection between the thin film and the driving electronics for the lead and its electrodes should be mechanically stable and electrically reliable. It appears that there are still possibilities for improvement, especially that such connections may be provided more easily.

It is therefore an object of the present invention to improve an electrical connection assembly and a corresponding method of manufacturing thereof, especially in that the mechanical stability and the electrical reliability is improved and the manufacturing is simplified.

The above object is solved according to the present invention with an electrical connection assembly with the features of claim 1. Accordingly, an electrical connection assembly for a medical implant comprises a thin film and a connector, wherein the thin film comprises at least one connector electrode, wherein the connector electrode has at least one hole, and wherein the connector comprises at least one contact and wherein the hole of the connector electrode is placed above the contact of the connector and the hole and the contact are contacted by means of conductive glue.

The electrical connection assembly has an improved mechanical stability and the electrical reliability and its manufacturing is simplified.

The present invention provides a mechanically stable and electrically reliable solution, how to connect a thin film with a contact. As a thin film is not easy to handle, but a placement of a thin film on another contact is possible without huge problems, the thin film may be placed firstly without glue on the contact. This allows a very accurate positioning, which is also needed when manufacturing microstructures for medical implants. To connect the thin film with the below contact, the hole can be used for an application of the glue and such a glue deposition may be possible through the hole by zero contact and forceless application.

The medical implant may be especially a medical implant for neurostimulation. For example, the medical implant may be a system for neural stimulation with an implantable lead with stimulation electrodes being connected with driving electronics.

The lead may be especially a lead for neurostimulation and may be for example a lead for deep brain stimulation, which is implanted into brain tissue to simulate regions of the brain.

The lead may e.g. comprise at least one thin film, wherein the thin film comprises a proximal end and a distal end, the lead further comprising a plurality of electrodes on the distal end of the thin film.

The thin film may include at least one electrically conductive layer, preferably made of a biocompatible material. The thin film may be assembled to the carrier and further processed to constitute the lead element. The thin film for a lead is preferably formed by a thin film product having a distal end, a cable with metal tracks and a proximal end. The distal end of the thin film may be forming a part of the distal end of the lead or merely the distal end of the lead.

Thin film structures provide the advantage that small structures can be built with this technology. A thin film is a layer or multilayer structure of material ranging from fractions of a nanometer (monolayer) to several micrometers in thickness. Electronic semiconductor devices and optical coatings are the main applications benefiting from thin-film construction. Thin film technology and thin film manufacturing processes allow the manufacturing of leads for medical purposes such as neurostimulation leads like e.g. deep brain stimulation leads with diameters of less than 2 mm, for example 0.75 mm to 1.50 mm and a plurality of electrodes (e.g. approx. 40 electrodes).

The distal end of the lead may be the end of the lead, which is in the implanted state of the lead the remote end of the lead with regard to the body surface area.

In particular, in case of a lead for brain applications, the distal end of the lead is the lower end of the lead, which is remote to the burr-hole of the skull, through which the lead is implanted.

The driving electronics of the system and the thin film may be connected by means of an electrical connection assembly as specified above.

The connector may be a printed circuit board. A printed circuit board comprises the advantage that the electronics of the medical implant may be integrated in a reliable and stable manner within the printed circuit board. Furthermore, using a printed circuit board allows a manufacturing process at reasonable costs also for a large number of pieces to be produced. A direct connection between a thin film and a printed circuit board helps to reduce the number of parts that are necessary for the medical implant.

The contact of the connector may be a contact pad of the printed circuit board. Such a contact pad forms a well-defined contact zone and is helpful to create a stable mechanical and an electrically reliable connection.

It is possible that the contact pad is a contact pin. A contact pin is a mechanically stable element and may help to improve the mechanical stability.

The conductive glue may be a conductive glue droplet. The application of the droplet can be easily done during manufacturing and the amount of glue can be adjusted. In particular, by applying droplets of glue a bleeding of glue that might create short-circuits can be avoided.

The glue droplet may be dispensed within the hole in such a way that the conductive glue contacts the edge(s) of the hole in the connector electrode and the contact of the connector. Such a deposition of glue helps to cover all or substantially all relevant conductive contact surfaces for the connection to be established between one connector electrode and the respective contact.

The glue droplet may form a kind of rivet. Such a rivet comprises the advantage that the hole of the electrode may be at least partially sealed and that the rivet-like droplet also provides enough stability against shear-stress.

The conductive glue may be a medically qualified adhesive, which is epoxy based and filled with gold particles. Such a conductive glue can be used for chronic implants, where the used components of the implant have to be of medical grade for biocompatibility reasons. Biocompatible elements are needed to avoid severe drawbacks like inflammation reactions or encapsulations. A possible example for such a currently available glue is marketed under the brandname Ablebond 8370.

Furthermore, the present invention relates to a probe for medical applications. Accordingly, a probe for medical applications, especially for neural applications, comprises at least one electrical connection assembly as specified above.

The probe may comprise all structural and functional features and also all advantages as specified above in connection with the electrical connection assembly according to the present invention and its possible embodiments.

Furthermore, the present invention relates to a system for medical applications, especially for neural applications. Accordingly, a system for medical applications comprises at least one electrical connection assembly as specified above.

The system may comprise all structural and functional features and also all advantages as specified above in connection with the electrical connection assembly according to the present invention and its possible embodiments.

Furthermore, the present invention relates to a method of providing an electrical connection between a thin film and a connector for a medical implant. Accordingly, the method of providing an electrical connection between a thin film and a connector for a medical implant, especially for a medical implant for neurostimulation, comprises the following steps: providing a thin film with at least one connector electrode, wherein the connector electrode has a hole; providing a connector with at least one contact; placing the hole of the connector electrode above the contact; and connecting the connector electrode and the contact by gluing with conductive glue.

The electrical connection received by this method may comprise all structural and functional features and also all advantages as specified above in connection with the electrical connection assembly according to the present invention and its possible embodiments.

The gluing may be done with a pin transfer technique.

For example, the glue may be picked up with a blunt needle from a layer of adhesive with a predetermined thickness, then moved to the deposition point and deposited into the hole of the connector electrode of the thin film.

Pin transfer is a technique for transferring very small amounts of adhesive onto a receiving substrate. For example, a component placer may be used such as a Datacon 2200 component placer. A blunt needle or pin can be used to pick up material from a layer of adhesive with a well defined thickness. After pickup, it moves to the deposition point and the glue droplet touches the substrate, thereby transferring a certain amount of adhesive to the substrate. Typically, the process is a contacting process, both during material pickup and during material deposition. This is achieved by mounting the needle to a spring creating some overtravel in the automatic movement of the system. In order not to damage the fragile substrate and to avoid the needle travelling into an open via, i.e. the hole, an overtravel may be for example set at around 0.1 mm, resulting for example in a contact force of approx. 0.05 N. The needle diameter may be for example approx. 200 pm, with a standoff diameter of approx. 125 pm and a standoff height of approx. 70 pm. The adhesive layer may be created using a squeegee. Together with the needle diameter, its thickness determines the amount of material transferred. Before each pickup operation, the layer may be refreshed to ensure repeatable material pickup. Typical transfer layers are in the order of approx. 50 p to 100 pm of thickness. The dot size of the deposited glue may be for example approx. 150-200 micron.

Further details and advantages of the present invention shall be described hereinafter with respect to the drawings. It is shown in:

Figure 1 a schematical drawing of a neurostimulation system for deep brain stimulation (DBS); - Figure 2 a further schematical drawing of a probe of a neurostimulation system for deep brain stimulation (DBS) and its components;

Figure 3 a schematical drawing of a probe system according to the present invention; and - Figure 4 a schematical cross-section of an electrical connection assembly according to the present invention received by the method of manufacturing according to the present invention. A possible embodiment of a neurostimulation system 100 for deep brain stimulation (DBS) is shown in Figure 1. The neurostimulation system 100 comprises at least a controller 110 that may be surgically implanted in the chest region of a patient 1, typically below the clavicle or in the abdominal region of a patient 1. The controller 110 can be adapted to supply the necessary voltage pulses. The typical DBS system 100 may further include an extension wire 120 connected to the controller 110 and running subcutaneously to the skull, preferably along the neck, where it terminates in a connector. A DBS lead arrangement 130 may be implanted in the brain tissue, e.g. through a burr-hole in the skull.

Figure 2 further illustrates a typical architecture for a Deep Brain Stimulation probe 130 that comprises a DBS lead 300 and an active lead can 111 comprising electronic means to address electrodes 132 on the distal end 304 of the thin film 301, which is arranged at the distal end 313 and next to the distal tip 315 of the DBS lead 300. The lead 300 comprises a carrier 302 for a thin film 301, said carrier 302 providing the mechanical configuration of the DBS lead 300 and the thin film 301. The thin film 301 may include at least one electrically conductive layer, preferably made of a biocompatible material. The thin film 301 is assembled to the carrier 302 and further processed to constitute the lead 300. The thin film 301 for a lead is preferably formed by a thin film product having a distal end 304, a cable 303 with metal tracks and a proximal end 310. The proximal end 310 of the thin film 301 arranged at the proximal end 311 of the lead 300 is electrically connected to the active lead can 111.

The active lead can 111 comprises the switch matrix of the DBS steering electronics. The distal end 304 comprises the electrodes 132 for the brain stimulation. The proximal end 310 comprises the interconnect contacts 305 for each metal line in the cable 303. The cable 303 comprises metal lines (not shown) to connect each distal electrodes 132 to a designated proximal contact 305. Figure 3 shows schematically and in greater detail an embodiment of a system 100 for brain applications, here for neurostimulation and/or neurorecording as a deep brain stimulation system 100 as shown in Figures 1 and 2. The probe system 100 comprises at least one probe 130 for brain applications with stimulation and/or recording electrodes 132, wherein e.g. 40 electrodes 132 can be provided on outer body surface at the distal end of the probe 130. By means of the extension wire 120 pulses P supplied by controller 110 can be transmitted to the active lead can 111. The controller 110 can be an implantable pulse generator 110.

Figure 4 shows a schematical cross-section of an electrical connection assembly 320 according to the present invention received by the method of manufacturing according to the present invention.

The electrical connection assembly 320 comprises a thin film 301 and a connector 322, here a printed circuit board with contact pins 324 as contacts.

To provide the electrical connection between the thin film 301 and the contact of the connector 322 for a medical implant, especially for a medical implant for neurostimulation, the method comprises the following steps:

Firstly, the thin film 301 is provided with at least one connector electrode 305 as proximal contacts 305. These connector electrodes 305 have holes 326.

Secondly, the connector 322, i.e. the printed circuit board, is provided having at least one contact, here contact pins 324.

The holes 326 of the connector electrodes 305 are placed above the contact, i.e. the contact pins 324, and then the connector electrodes 305 and the contact pins 324 are connected by gluing with conductive glue 328.

The conductive glue 328 is a conductive glue droplet and a medically qualified adhesive, which is epoxy based and filled with gold particles.

The gluing is done with a pin transfer technique. The glue is picked up with a blunt needle from a layer of adhesive with a predetermined thickness, then moved to the deposition point and deposited into the hole of the connector electrode of the thin film.

As can be seen in Figure 4, the glue droplet is dispensed within the hole 326 in such a way that the conductive glue 328 contacts the edge(s) of the hole 326 in the connector electrode 305 and the contact pin 324 of the connector 322.

The glue droplet forms a kind of rivet.

At the end of this process an electrical connection assembly 320 for a medical implant, especially for a medical implant for neurostimulation is received.

This electrical connection assembly 320 comprises the thin film 301 and a connector 322. The thin film 301 comprises at least one, here several connector electrodes 305 (corresponding to the number of electrodes 132 of the lead 300), wherein the connector electrodes 305 have one hole 326. The connector 322, i.e. the printed circuit board, comprises at least one contact, i.e. the contact pin 324, and the hole 326 of the connector electrode 305 is placed above the contact of the connector 322 and the hole 326 and the contact are contacted by means of conductive glue 328.

The function provided by the electrical connection assembly is an improved mechanical stability and the electrical reliability for the connection of the thin film 301 to e.g. the electronics within the advanced lead can 111. Furthermore, the connection is very accurate and thus many connections may be provided without consuming too much space. This is especially relevant when providing electrical connections for medical implants that need microparts such as deep brain stimulation systems 100.

The lead may be especially a lead 300 for neurostimulation and may be for example a lead 300 of a system 100 for deep brain stimulation, which is implanted in to brain tissue to simulate regions of the brain.

The above disclosure may be used in connection with Deep Brain Stimulation, catheters with intelligent tips, hearing aids such as cochlear implants as e.g. hearing aids, pacemakers, ICD implants or generally implants with stimulating and sensing functions.

Here follows the translation of the Dutch text on the next pages: 1. An electrical connection assembly (320) for a medical implant, especially for a medical implant for neurostimulation, comprising a thin film (301) and a connector (322), wherein the thin film (301) comprises at least one connector electrode (305), wherein the connector electrode (305) has at least one hole (326), and wherein the connector (322) comprises at least one contact and wherein the hole (326) of the connector electrode (305) is placed above the contact of the connector (322) and the hole (326) and the contact are contacted by means of conductive glue (328). 2. The electrical connection assembly (320) according to claim 1, wherein the connector (322) is a printed circuit board. 3. The electrical connection assembly (320) according to claim 2, wherein the contact of the connector is a contact pad of the printed circuit board. 4. The electrical connection assembly (320) according to claim 3, wherein the contact pad is a contact pin (324). 5. The electrical connection assembly (320) according to one of the preceding claims, wherein the conductive glue (328) is a conductive glue droplet. 6. The electrical connection assembly (320) according to claim 5, wherein the glue droplet is dispensed within the hole (326) in such a way that the conductive glue (328) contacts the edge of the hole (326) in the connector electrode (305) and the contact of the connector (322). 7. The electrical connection assembly (320) according to one of claims 5 or 6, wherein the glue droplet forms a kind of rivet. 8. The electrical connection assembly (320) according to one of the preceding claims, wherein the conductive glue (328) is a medically qualified adhesive, which is epoxy based and filled with gold particles. 9. A probe (130) for medical applications, especially for neural applications, comprising at least one electrical connection assembly (320) according to one of the preceding claims. 10. A system (100) for medical applications, especially for neural applications, comprising at least one electrical connection assembly (320) according to one of claim 1 to 8 and/or a probe for medical applications according to claim 9. 11. A method of providing an electrical connection between a thin film (301) and a connector for a medical implant, especially for a medical implant for neurostimulation, the method comprising the following steps: providing a thin film (301) with at least one connector electrode (305), wherein the connector electrode (305) has a hole (326); providing a connector (322) with at least one contact; placing the hole (326) of the connector electrode above the contact; and connecting the connector electrode (305) and the contact by gluing with conductive glue (328). 12. The method according to claim 11, wherein the gluing is done with a pin transfer technique. 13. The method according to claim 12, wherein the conductive glue (328) is picked up with a blunt needle from a layer of adhesive with a predetermined thickness, then moved to the deposition point and deposited into the hole (326) of the connector electrode (305) of the thin film (301).

Claims

An electrical connection assembly (320) for a medical implant, in particular for a medical implant for neurostimulation, comprising a thin film (301) and a connector (322), the thin film (301) having at least one connector electrode (305), wherein the connector electrode (305) has at least one opening (326), and wherein the connector (322) comprises at least one contact and wherein the opening (326) of the connector electrode (305) above the contact of the connector (322) and the hole (326) and the contact and the opening make mutual contact by means of conductive glue (328).

The electrical connection assembly (320) of claim 1, wherein the connector (322) is a printed circuit board.

The electrical connection assembly (320) of claim 2, wherein the contact of the connector is a contact surface of the circuit board.

The electrical connection assembly (320) of claim 3, wherein the contact surface is a contact pin (324).

The electrical connection assembly (320) of any one of the preceding claims, wherein the conductive glue (328) is a conductive glue drop.

The electrical connection assembly (320) of claim 5, wherein the glue drop is disposed in the opening (326) such that the conductive glue (328) contacts the edge of the opening (326) in the connector electrode (305) ) and with the contact of the connector (322).

The electrical connection assembly (320) according to claim 5 or 6, wherein the glue drop forms a kind of rivet.

The electrical connection assembly (320) according to any of the preceding claims, wherein the conductive adhesive (328) is a medically qualified epoxy-based adhesive and filled with gold particles.

A probe (130) for medical applications, in particular for neural applications, comprising at least one electrical connection assembly (320) according to any one of the preceding claims.

A system (100) for medical applications, in particular for neural applications, comprising at least one electrical connection assembly (320) according to any of claims 1 to 8 and / or a probe for medical applications according to claim 9. A method for providing an electrical connection between a thin film (301) and a connector for a medical implant, in particular for a medical implant for neurostimulation, the method comprising the steps of: - providing a thin film (301) with at least one connector electrode (305), the connector electrode (305) having an opening (326); - providing a connector (322) with at least one contact; - placing the opening (326) of the connector electrode above the contact; and - connecting the connector electrode (305) and the contact by gluing with conductive glue (328).

The method according to claim 11, wherein the gluing is by transfer with a pin (pin transfer technique).

The method of claim 12, wherein the conductive glue (328) is received with a blunt needle of a layer of adhesive with a predetermined thickness, then moved to the deposition point and disposed in the opening (326) of the connector electrode (305) ) of the thin film (301).