AT527117B1 - high-pressure viewing cell for microfluid applications - Google Patents

Abstract

The invention relates to a high-pressure viewing cell (1) for optically observing a microfluidic chip (2), wherein the microfluidic chip (2) can be arranged in a sample receiving space (3) of the high-pressure viewing cell (1), wherein the high-pressure viewing cell (1) has a window element (5) for observing the microfluidic chip (2) through the window element (5) and a window element holder (7) for holding the window element (5), wherein in order to produce a connection between the window element holder (7) and the window element (5), the window element (5) is tapered at least in sections from an internal pressure side of the window element (5) to an external pressure side of the window element (5). The high-pressure viewing cell (1) has a holding device (4) in the sample receiving space (3) for arranging, in particular detachably, the microfluidic chip (2) in order to supply an examination fluid to a microfluid channel system of the microfluidic chip (2) via a fluid inlet of the microfluidic chip (2), wherein the holding device (4) has a chip carrier in order to arrange the microfluidic chip (2) on the holding device and is designed to arrange the microfluidic chip (2) in the sample receiving space (3) during use, such that the microfluidic chip (2) can be subjected to a filling medium pressure of a filling medium that can be filled into the sample receiving space (3) from a top and bottom.

Description

Description

HIGH-PRESSURE VISION CELL FOR MICROFLUID APPLICATIONS

[0001] The invention relates to a high-pressure viewing cell for optically observing a microfluidic chip, wherein the microfluidic chip can be arranged in a sample receiving space of the high-pressure viewing cell, wherein the high-pressure viewing cell has a window element for observing the microfluidic chip through the window element and a window element holder for holding the window element, wherein in order to produce a connection, in particular a positive and/or non-positive connection, between the window element holder and the window element, the window element is tapered at least in sections from an internal pressure side of the window element to an external pressure side of the window element.

[0002] In order to investigate the flow behavior of a fluid medium in a rock of underground deposits, it is known to simulate a rock structure of the rock with a microfluid chip, wherein a microfluid channel system of the microfluid chip is designed to correspond to a rock porosity or a rock channel system of the rock. For this purpose, it is usually provided that the microfluid chip is held with a holding device and an examination fluid, usually corresponding to the fluid medium, is introduced into the microfluid channel system via a fluid inlet of the microfluid chip in order to investigate the flow behavior of the examination fluid in the microfluid channel system, usually under microscopic observation. For example, with a view to exploring oil extraction from the rock, oil can first be introduced into the microfluid channel system in order to then investigate the possibility of extracting the oil from the rock by introducing water into the microfluid channel system. The microfluidic chip is usually designed to be light-permeable in order to observe the flow behavior of the test fluid in the microfluidic channel system by illuminating the microfluidic chip with a microscope.

[0003] To investigate the flow behavior of the examination fluid under high pressure conditions, frequently at an examination fluid pressure of several 100 bar, it is usually provided that the holding device with the microfluid chip is arranged in a receiving space of a high-pressure viewing cell, wherein the receiving space is filled with a filling fluid, usually with water, wherein a filling fluid pressure corresponding to the examination fluid pressure is set in the filling fluid. In this way, a load exerted on a structure of the microfluid chip by the examination fluid pressure can be compensated to a large extent with the filling fluid pressure in order to maintain the structural integrity of the microfluid chip. The high-pressure viewing cell usually has a cuboid window element held by a window element holder of the high-pressure viewing cell in order to observe the flow behavior of the examination fluid in the microfluid channel system with a microscope from an external pressure side of the window element through the window element. To hold the window element, the window element holder usually has an annular support element which rests on an outer surface of the window element in order to apply a pressing force to the window element with the support element.

[0004] The document DE 689 15 264 T2 relates to a crystallographic examination device with a pressure vessel which has hemispherical observation windows for observing crystal growth.

[0005] The document WO 2023/003489 A1 relates to a high-pressure holder for a microfluidic chip, wherein an adapter holder for holding the microfluidic chip is arranged between a base and a cover and a glass window is inserted into the cover.

[0006] The document EP 0 493 746 A2 relates to a high-pressure window arrangement for a chromatographic detector, wherein windows have conical side contours in the direction of their inner and outer transparent surfaces.

[0007] The document DE 203 11 434 U1 relates to a device for observing objects under high pressure, wherein conically fitted panes are provided in window element holders

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are.

[0008] The document DE 38 22 445 A1 relates to an optical high-pressure transmission cell for infrared spectroscopy, wherein windows are designed as stepped windows with a central, cylindrical extension.

[0009] This is where the invention comes in. The object of the invention is to provide a high-pressure viewing cell of the type mentioned at the outset, which has a high usability, in particular with regard to optical observation of a sample, in particular a microfluidic chip or an examination fluid in a microfluidic channel system of the microfluidic chip.

[0010] The object is achieved according to the invention in that, in a high-pressure viewing cell of the type mentioned at the outset, the high-pressure viewing cell in the sample receiving space has a holding device for, in particular detachably, arranging the microfluidic chip in order to supply an examination fluid to a microfluid channel system of the microfluidic chip via a fluid inlet of the microfluidic chip, wherein the holding device has a chip carrier in order to arrange the microfluidic chip on the holding device and is designed to arrange the microfluidic chip in the sample receiving space in such a way that the microfluidic chip can be subjected to a filling medium pressure of a filling medium with which the sample receiving space can be filled from an upper side and an underside of the microfluidic chip.

[0011] It has been shown that during an optical examination of a sample, which is a microfluidic chip, or of an examination fluid in a microfluidic channel system of the microfluidic chip, usually with a microscope through a window element of a high-pressure viewing cell, a reduction in a working distance of the microscope or an approach of the microscope to the window element is usually limited by a window element holder holding the window element, in particular a support element of the window element holder, which support element is arranged in front of the window element on the outside. This usually represents a limitation for the quality of the optical examination or of an optical image with the microscope. The basis of the invention is the idea of implementing a design of an arrangement of the window element with the window element holder in such a way that a greater approach of an optical measuring device or microscope on the outside to the window element is possible or a working distance of the optical measuring device or microscope can be reduced.

[0012] According to the invention, the sample is designed as a microfluid chip. The filling medium is a filling fluid. By designing the window element to be tapered from an internal pressure side of the window element to an external pressure side of the window element or in an external direction of the window element at least in sections, in particular predominantly, preferably substantially, the window element can be held with the window element holder, in particular in a form-fitting and/or force-fitting manner, in such a way that a high degree of free space can be achieved in front of the window element on the external pressure side or a distance between an optical measuring device, in particular a microscope, arranged in an insert in front of the window element on the external pressure side for measuring through the window element and the window element can be reduced. This makes it possible to increase the quality of the measurement, in particular the microscopic measurement. In particular, a high resolution or large numerical aperture of the optical measurement, in particular the microscopic measurement, can be implemented. This is particularly relevant if microstructures are to be observed under high pressure. This is especially true if the sample is a microfluidic chip or an examination fluid in a microfluidic channel system of a microfluidic chip.

[0013] An internal pressure usually refers to a pressure in the sample receiving space of the high-pressure viewing cell, in particular a filling fluid pressure of a filling fluid with which the sample receiving space can be filled when the high-pressure viewing cell is in use. In use, the internal pressure side of the window element is usually loaded with the filling fluid pressure or the external pressure side of the window element is loaded with an external pressure of an environment outside the sample receiving space. In use, an optical measurement or observation of the sample is usually carried out through the window element. The internal pressure is in the

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Usually greater than 100 bar. The internal pressure is usually from 100 bar to 4000 bar, in particular from 250 bar to 1000 bar. Usually an external pressure refers to a pressure outside the sample receiving space, in particular to an external pressure or ambient pressure around the high-pressure sight cell when the high-pressure sight cell is in use. The external pressure or ambient pressure is usually less than 5 bar, in particular between 0.5 bar and 2 bar. In particular, the high-pressure sight cell is designed for use at such pressures.

[0014] The internal pressure side or inner side, in particular of the window element, usually refers to a side facing the sample receiving space, in particular of the window element. The external pressure side or outer side, in particular of the window element, usually refers to a side facing away from the sample receiving space, in particular of the window element. The internal pressure side and external pressure side of the window element are usually opposite one another on the window element. The window element and/or the window element holder are usually part of a sample receiving space wall of the sample receiving space that delimits the sample receiving space. The window element, in particular an internal transparent surface of the window element, usually borders the sample receiving space. An external direction of the window element is usually oriented from the internal pressure side to the external pressure side of the window element.

[0015] The window element holder usually has a support element. It is advantageous if the window element holder, in particular the support element, positively delimits the window element on a side surface of the window element, which side surface runs between an inner transparent surface of the window element facing the sample receiving space and an outer transparent surface of the window element located outside the sample receiving space. The support element usually forms a stop for the window element, in particular the side surface of the window element, in the outward direction of the window element. The side surface of the window element is usually pressed against the support element. In particular, the window element can thus be held laterally by the window element holder. In particular, this enables the window element to be held with the window element holder with reduced space requirements by the window element holder on the outside in front of the window element, in particular the outer transparent surface. The respective transparent surface is usually a surface area of the window element through which the sample can be observed during use. The inner see-through surface and/or the outer see-through surface can expediently be essentially flat. The outer direction of the window element is usually oriented essentially orthogonally to the inner see-through surface and/or the outer see-through surface. The window element can have a see-through direction in which, during use, the sample can be observed through the window element from outside the sample receiving space. The outer direction can be oriented opposite to the see-through direction. When viewed opposite to the outer direction of the window element onto the window element, the side surface usually runs circumferentially around the window element. The window element and the window element holder are usually connected to one another in a form-fitting and/or force-fitting manner. The window element and the window element holder are usually connected to one another in a fluid-tight manner. For this purpose, the high-pressure viewing cell can have one or more sealing elements which are arranged between the window element and the window element holder, in particular between adjoining surfaces of these.

[0016] The window element can have a side contour tapering in the outward direction at least in sections in a first cross section through the window element running parallel to the outward direction of the window element. The window element can have a side contour tapering in the outward direction at least in sections in a second cross section through the window element running parallel to the outward direction of the window element, which is oriented orthogonally to the first cross section. The respective side contour is usually formed with the, in particular by the, side surface. It is advantageous if the tapered side contour extends over more than 50%, in particular more than 75%, of an average height of the window element in the outward direction of the window element. A high level of robustness

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can be achieved if, in the respective cross-section, the window element has a first section which is arranged in the outward direction in front of a second section with the, in particular, aforementioned, tapered side contour, wherein the first section has side contour lines oriented essentially parallel to one another. Usually, the side contour lines of the first section adjoin on the inside to an inner contour line facing the sample receiving space, in particular representing the inner transparent surface. It is advantageous if the first section, in particular its side contour lines, extend over more than 2%, in particular more than 5%, of an average height of the window element in the outward direction of the window element. Usually, in the respective cross-section, the, in particular tapered, side contour refers to side contour lines of the window element which are opposite one another in relation to a central axis oriented in the outward direction.

[0017] It has proven useful if the side surface is designed at least in sections, in particular predominantly, preferably essentially, as a rotation surface, in particular a conical surface, tapering in the outward direction of the window element. The outward direction usually runs from the inner pressure side of the window element to the outer pressure side of the window element. The outward direction can be oriented opposite to the viewing direction of the window element. An axis of rotation of the rotation surface is usually parallel to the outward direction of the window element and preferably runs through a center of the window element.

[0018] It is advantageous if the window element holder, in particular the support element, forms a through-channel into which the window element is at least partially, preferably substantially completely, inserted in a form-fitting manner. The window element is usually at least partially inserted into the through-channel in the outward direction of the window element. The support element usually forms a stop for the window element, in particular the side surface, in the outward direction of the window element. A through-channel wall forming the through-channel is usually designed to correspond in shape to the side surface of the window element. The window element is usually inserted into the through-channel in such a way that the side surface is pressed against the through-channel wall. In this way, a robust fixation of the window element can be implemented. The through-channel, in particular the through-channel wall, usually extends completely through the support element. A contact surface, on which the side surface and the through-channel wall adjoin one another, in particular contact one another, usually pressed against one another, can expediently run substantially circumferentially around the window element. This applies in particular to a view of the window element against the outward direction of the window element. It has proven useful if the contact surface is designed at least in sections, preferably essentially, as a rotation surface, in particular a conical surface, tapering in the outward direction of the window element. A rotation axis of the rotation surface is usually essentially parallel to the outward direction of the window element. The through-opening wall can form a window element receptacle, in particular a sleeve-shaped one, into which the window element is at least partially, in particular essentially completely, inserted in the outward direction of the window element, forming a positive connection in the outward direction. The window element receptacle or through-opening wall is usually designed to correspond in shape to the side surface of the window element. A channel axis running from an inside opening of the through-channel to an outside opening of the through-channel is usually oriented essentially parallel to the outward direction. The window element is usually at least partially inserted into the through-channel through the inside opening of the through-channel.

[0019] It is practical if the window element holder has a pressing surface, in particular formed with an elastically and/or plastically deformable sealing material, wherein the side surface is pressed against the pressing surface in order to implement a fluid-tight press connection or to connect the window element and the window element holder to one another in a fluid-tight manner. The sealing material can be formed, for example, with, in particular from, an elastomer, for example rubber. The pressing surface can be part of the support element, in particular

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or as part of the through-channel wall or arranged on it. The pressing surface can be formed with one or more sealing elements. The sealing element can be, for example, a sealing ring, in particular made of an aforementioned sealing material. The sealing element can be partially inserted, usually in a form-fitting manner, into a recess in the support element, in particular the through-channel wall, which recess is designed to correspond in shape to the sealing element. The pressing surface is usually arranged circumferentially around the window element, in particular running along the side surface, in particular when viewed against the outward direction of the window element. The support element usually runs circumferentially around the window element on the lateral side, with the support element forming a stop for the window element in the outward direction of the window element.

[0020] It is advantageous if the window element holder has an actuating device in order to press the window element against the window element holder, in particular against the support element, when the actuating device is actuated and/or to change a pressing force between the window element, in particular the support element, and the window element holder. The actuating device can have an actuating element that is movable relative to the support element, in particular in order to exert a pressing force on the window element with the actuating element when the actuating device is actuated, so that the window element is pressed against the support element. In particular, when the actuating device is actuated, the side surface of the window element can be pressed against the through-channel wall, in particular the pressing surface, and/or a pressing force between the side surface and the through-channel wall can be changed. It is advantageous if the actuating device, in particular the actuating element, forms a stop, in particular a movable stop, for the window element against the outward direction of the window element. This can expediently be a movable stop for a surface of the window element facing the sample receiving space of the high-pressure viewing cell, in particular the internal pressure side surface.

[0021] It is practical to use the window element holder if it is detachably connected to a basic structure of the high-pressure viewing cell, whereby the window element holder can be detached from the basic structure without releasing the connection, in particular the force-fitting connection, in particular a press connection, and/or a form-fitting connection, between the window element holder and the window element. In particular, this can be done without releasing a pressing of the window element, in particular the side surface of the window element, against the support element, in particular the through-channel wall. The window element holder can expediently have a closure element that is movable relative to the support element, in particular with which closure element the window element is detachably enclosed in the through-channel. The closure element can form a detachable stop for the window element, which prevents the window element from being released from the through-channel. It is expedient if the closure element at least partially closes the through-channel against removal of the window element from the through-channel, usually on a side of the window element facing the sample receiving space. The closure element can be detachably connected to the support element, in particular in a force-fitting and/or form-fitting manner, usually with a connecting device, for example a screw connection, of the window element holder. The closure element can be partially or essentially completely inserted into the through-channel, in particular via a through-channel opening of the through-channel facing the sample receiving space. It is practical if the closure element is reversibly screwed into the support element, in particular into the through-channel, with a thread. For example, the closure element can be a threaded ring which can be screwed into the through-channel wall, in particular in an extension direction of the through-channel. For this purpose, a surface of the through-channel wall can have a counter-thread corresponding to a thread of the threaded ring. The closure element can be the actuating element. The closure element and the actuating element can be different parts. The closure element and the support element can form two separate parts. The basic structure can be formed with one or more sample receiving chamber walls, whereby the sample receiving chamber is usually formed by connecting the basic structure and the window element holder including the window element.

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[0022] It is practical if the window element holder is detachably connected to a basic structure of the high-pressure viewing cell, wherein the window element holder is pressed against the basic structure, in particular against a counter surface of the basic structure, by means of a fastening element, in particular one that runs circumferentially around the window element holder. This is usually done by forming a positive connection between the window element holder and the fastening element. The fastening element can be connected to the basic structure by means of a screw connection of the high-pressure viewing cell, in particular the fastening element and/or the basic structure. The fastening element is preferably connected to the basic structure by screwing in the fastening element, wherein, for example, a thread of the fastening element, in particular running circumferentially around the fastening element, is screwed into a counter thread of the basic structure. The fastening element can expediently be coupled to the basic structure in such a way that a pressing force exerted on the window element holder by the fastening element can be changed, in particular adjusted, for example with the screw connection, in particular by screwing in the fastening element. The fastening element can run circumferentially around the window element holder in order to apply a pressing force to the window element holder along a circumference of the window element holder using the fastening element. For example, the fastening element can be a fastening sleeve, wherein the fastening sleeve encloses the window element holder circumferentially, in particular in a form-fitting manner.

[0023] The window element holder can expediently have a recess and the fastening element can have a projection, in particular one that corresponds in shape to the recess, the projection being at least partially inserted into the recess so that the projection forms a stop for a recess surface of the recess in the outward direction of the window element. The recess is usually arranged on an outer surface of the window element holder. The recess surface can form a contact area via which a pressing force is applied to the window element holder with the fastening element, in particular the projection, to press the window element holder against the counter surface. The fastening element can have several projections, each of which is at least partially inserted into at least one recess. It has proven useful if the recess is implemented with a, in particular as a stepped edge region of the window element holder, the stepped edge region forming a, in particular flat, stepped surface on which the projection of the fastening element engages to form a stop in the outward direction. The stepped edge region can be formed in a radial direction. The radial direction can refer to a circumference around the window element, which circumference usually lies in a plane transverse, in particular orthogonal, to the outer direction. The stepped surface can be formed by an edge-side recess of the fastening element.

[0024] The window element holder usually has a contact surface which is pressed against a counter surface of the basic structure to connect the window element holder and the basic structure. An interface formed by the contact surface and the counter surface, at which the contact surface and the counter surface adjoin one another, can be formed with a sealing element, in particular a sealing ring, in order to implement a fluid-tight connection between the contact surface and the counter surface. The sealing element can be arranged in a form-fitting manner in part in a recess in the contact surface and/or the counter surface, which recess has a shape corresponding to the sealing element. The sealing element can be designed analogously to that described above, in particular with an elastically and/or plastically deformable sealing material.

[0025] It is advantageous if the window element holder does not overlap the outside viewing area. It has proven to be useful if, in a cross section parallel to the outside direction of the window element, the window element holder and the window element on the outside, in particular in the outside direction of the window element, have outer contours that are essentially at the same height. In particular, in the cross section, the window element holder and the window element on the outside can have outer contours that are essentially aligned with one another.

[0026] The high-pressure viewing cell has a holding device in the sample receiving space for, in particular,

particularly detachable arrangement of a microfluidic chip in the sample receiving space. The microfluidic chip, in particular an examination fluid located in a microfluid channel system of the microchip during use, can represent the sample. In use, an examination fluid can expediently be supplied to a microfluid channel system of the microfluid chip via a fluid inlet of the microfluid chip for the microfluid chip arranged with the holding device. The high-pressure viewing cell can have at least one supply line in order to supply examination fluid to a microfluid chip arranged with the holding device from outside the sample receiving space via the supply line via a fluid inlet of the microfluid chip, and/or at least one discharge line in order to discharge examination fluid from the microfluid chip arranged with the holding device via the discharge line to outside the sample receiving space via a fluid outlet of the microfluid chip during use. The supply line and/or the discharge line can run at least partially through the sample receiving space. The fluid inlet and/or fluid outlet of the microfluidic chip are usually connected in a fluid-conducting manner to the microfluidic channel system of the microfluidic chip. The holding device can have one or more fluid connections via which the supply line and/or discharge line can be connected in a fluid-conducting manner to the microfluidic chip, in particular its fluid inlet and/or fluid outlet, when the microfluidic chip is arranged with the holding device. The supply line and/or discharge line can each be connected in a fluid-conducting manner to a connection leadthrough of the high-pressure viewing cell, which is led through a sample receiving chamber wall of the sample receiving chamber, in order to lead examination fluid through the sample receiving chamber wall via the connection leadthrough. The connection leadthrough can be part of the supply line or discharge line. The supply line or discharge line usually form a fluid receiving volume into which examination fluid can be led during use, which fluid receiving volume is separated from the sample receiving chamber, in particular a receiving cavity of the sample receiving chamber. During use, the fluid receiving volumes can be filled with an examination medium that is separate from the filling medium with which the sample receiving space, in particular its receiving cavity, is filled.

[0027] The fluid inlet or fluid outlet of the microfluidic chip is usually connected to the microfluidic channel system of the microfluidic chip in a fluid-conducting manner. The microfluidic channel system is usually formed with several fluid channels connected to one another in a fluid-conducting manner. In this way, a rock porosity or a rock channel system through which a fluid can be guided can be simulated with the microfluidic chip or the microfluidic channel system. The microfluidic channel system usually has a volume for accommodating fluid of between 5 μl and 100 μl. A diameter of the fluid channels is usually less than 1000 μm, in particular less than 500 μm, in particular less than 50 μm. The microfluidic chip is usually plate-shaped. The microfluidic chip usually has a length and a width of less than 10 cm each. The height of the microfluidic chip is usually orthogonal to a length and width of the microfluidic chip, whereby the height is usually smaller than the length and width of the microfluidic chip. The microfluidic chip usually has two light-transmissible or transparent cover surfaces, usually made of quartz glass, between which the microfluidic channel structure is formed. The cover surfaces are usually oriented parallel to a longitudinal extension and a width extension of the microfluidic chip. The microfluidic chip can be part of the high-pressure viewing cell. The cover surfaces are usually opposite one another on the microfluidic chip. According to the invention, the holding device is designed to arrange the microfluidic chip in the sample receiving space in such a way that the microfluidic chip can be subjected to a filling medium pressure of a filling medium with which the sample receiving space can be filled from a top and a bottom of the microfluidic chip. When the sample receiving space is filled with the filling medium, the filling medium usually borders on the cover surfaces of the microfluidic chip. The holding device has a chip carrier which is designed to arrange or fix a microfluidic chip, in particular detachably, on the holding device.

[0028] As a rule, the high-pressure viewing cell has an inlet line for supplying a filling fluid into the sample receiving chamber and/or an outlet line for removing filling fluid from

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the sample receiving chamber. The sample receiving chamber usually defines a receiving cavity which can be filled with the filling fluid. The input line and/or the output line can each be fluidically connected to a connection leadthrough of the high-pressure viewing cell which is led through a sample receiving chamber wall of the sample receiving chamber, in particular connected to this, in order to lead filling fluid through the sample receiving chamber wall via the connection leadthrough.

[0029] It is advantageous if the high-pressure viewing cell has a temperature control device in order to temperature control, in particular to heat and/or cool, fluid that is supplied to the sample receiving space or is supplied to it when used with the temperature control device. The fluid can be the filling fluid and/or the examination fluid. The temperature control device can be formed with one or more heating devices and/or cooling devices. The temperature control device can be implemented, for example, with an electrical resistance heater, one or more Peltier elements and/or a temperature control channel through which a temperature control medium flows. The high-pressure viewing cell can expediently have one or more temperature sensors in order to control the temperature control device depending on a measurement result of the temperature sensors. This can be implemented with an electronic control device of the high-pressure viewing cell. The temperature sensor, in particular an electrical connection cable and/or a temperature measuring head of the temperature sensor, can be introduced into the sample receiving chamber, in particular a close area of the holding device, via a measurement feedthrough channel that passes through a sample receiving chamber wall. The measurement feedthrough channel can have a fluid receiving volume that is spatially separated from the sample receiving chamber, in particular the receiving cavity, in which the temperature sensor, in particular its electrical connection cable and/or the temperature measuring head are located. It is advantageous if the temperature control device is designed to temperature control, in particular to heat and/or cool, connection feedthroughs that pass through the sample receiving chamber wall for conducting fluid, in particular filling fluid and/or examination fluid, through the sample receiving chamber wall in order to temperature control the fluid. The temperature control device can have a heat transfer surface that contacts a sample receiving chamber wall of the sample receiving chamber, in particular on the outside, in a heat-transferring manner in order to temperature control the respective fluid through the sample receiving chamber wall. The heat transfer surface can extend circumferentially around the sample receiving chamber, contacting the sample receiving chamber wall in a heat-transferring manner. The heat transfer surface can be formed with a temperature control band, in particular a heating band and/or cooling band.

[0030] In use, a sample arranged in the sample receiving space, in particular a microfluid chip held with the holding device, can be observed with an optical measuring device, in particular a microscope, arranged in front of the window element or outside the sample receiving space against the outward direction of the window element. The optical measuring device, in particular the microscope, can be part of the high-pressure viewing cell.

[0031] The window element can be formed with, in particular essentially from, glass. It is preferred if the window element is formed with, in particular from, sapphire, in particular sapphire glass. The window element holder is usually formed with, in particular essentially from, metal, in particular an iron alloy, preferably steel. The sample receiving space, in particular its receiving cavity, can have a freely selectable size depending on the intended use. It is particularly advantageous, in particular with regard to an examination of a microfluid chip or of examination fluid in its microfluid channel system, if the sample receiving space, in particular its receiving cavity, has a volume between 5 ml and 1000 ml, in particular between 10 ml and 500 ml, preferably between 15 ml and 100 ml, particularly preferably between 20 ml and 50 ml. It has proven useful if the holding device is designed to arrange a microfluidic chip in such a way that an average distance between the microfluidic chip and the inner transparent surface of the window element is less than 2 cm. The distance is usually between 0.1 mm and 10 mm, preferably between 0.2 mm and 0.7 mm. The distance can be a distance corresponding to the window.

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terelement facing outer surface, in particular the cover surface, of the microfluidic chip. The distance usually refers to the window element through which an optical observation or measurement of the sample or the microfluidic chip takes place.

[0032] For high usability, it is advantageous if the high-pressure viewing cell has several window element arrangements, in particular a first window element arrangement and a second window element arrangement, wherein the respective window element arrangement comprises a window element holder and a window element held by the window element holder, wherein the window element arrangements, in particular the window elements, are arranged on different, in particular opposite, sides of the sample receiving space. In particular, in this way, during use, a sample located in the sample receiving space can be illuminated through one of the window elements with light from an illumination device and observed through the other window element with an optical measuring device, in particular with a microscope. The window element holder and the window element of the respective window element arrangement can be implemented as described in this document. The respective window element holder and the respective window element can be referred to as the first or second window element and as the first or second window element holder, analogously to the designation of the respective first or second window element arrangement. The optical measuring device and/or the illumination device can be part of the high-pressure viewing cell. In particular, the optical measuring device, in particular the microscope, can be arranged in front of the first window element against the outward direction of the first window element in order to observe the sample with the optical measuring device through the first window element, in particular to examine it optically. The lighting device can be arranged in front of the second window element against the outward direction of the second window element in order to irradiate the sample with light through the second window element using the lighting arrangement. The holding device can be designed to arrange the microfluidic chip in the sample receiving space in such a way that one of the cover surfaces of the microfluidic chip faces the first window element and the other cover surface of the microfluidic chip faces the second window element.

[0033] Inside or inside with respect to a component of the high-pressure viewing cell, in the context of what is described in this document, usually refers to a side of the component facing the sample receiving space. Outside or outside with respect to a component of the high-pressure viewing cell, in the context of what is described in this document, usually refers to a side of the component facing away from the sample receiving space, in particular opposite the sample receiving space on the component. Use, in particular of the high-pressure viewing cell, usually refers to a state of the high-pressure cell in which the sample receiving space, in particular a filling fluid volume of the sample receiving space, is filled with filling fluid, and a sample located in the sample receiving space is observed through the window element. Stop for a component in a certain direction of the component usually refers to a stop for a movement of the component in this direction.

[0034] Further features, advantages and effects of the invention emerge from the following illustration of an embodiment. In the drawings, to which reference is made, show:

[0035] Fig. 1 is a schematic representation of a high-pressure viewing cell for optical observation of a microfluidic chip, in particular a flow of an examination fluid in a microfluidic channel system of the microfluidic chip;

[0036] Fig. 2 and Fig. 3 are schematic representations of cross sections through the high-pressure viewing cell of Fig. 1;

[0037] Fig. 4 is a schematic representation of a window element of the high-pressure viewing cell of Fig. 1 held by a window element holder in a cross section through the high-pressure viewing cell.

[0038] Fig. 1 shows a schematic view of a high-pressure viewing cell 1 for optically observing a microfluid chip 2, in particular a flow of a fluid under investigation in a microfluid channel system of the microfluid chip 2. The high-pressure viewing cell 1 has a sample receiving chamber 3 for receiving the microfluid chip 2, wherein the microfluid chip 2 is usually arranged, in particular held, in the sample receiving chamber 3 by a holding device 4 of the microfluid chip 2. The high-pressure viewing cell 1 has at least one window element 5 in order to observe, in particular optically measure, the microfluid chip 2 or its microfluid channel system from outside the sample receiving chamber 3 through the window element 5. The window element 5 usually forms part of a sample receiving chamber wall of the sample receiving chamber 3. It is advantageous if the high-pressure viewing cell 1 has two window elements 5 that are opposite one another in relation to the sample receiving chamber 3. The high-pressure viewing cell 1 is designed such that, during use, the sample receiving space 3 is filled with a filling fluid, for example water, with a high filling fluid pressure. Usually, during use, an outer surface of the microfluidic chip 2 is in direct contact with the filling fluid, so that the outer surface is subjected to the filling fluid pressure. Fig. 2 and Fig. 3 show schematic representations of cross sections through the high-pressure viewing cell 1 of Fig. 1, whereby in Fig. 3, fluid lines, in particular examination fluid lines 6 for supplying and/or removing examination fluid to or from the microfluid channel system of the microfluidic chip 2, are not shown in order to make the structure easier to recognize. The high-pressure viewing cell 1 usually has a filling fluid line 24, in particular a filling fluid inlet line and/or a filling fluid outlet line, in order to supply filling fluid to the sample receiving chamber 3, in particular to a receiving cavity of the sample chamber, via the filling fluid line 24 from outside the sample receiving chamber 3, in particular to supply it via the filling fluid inlet line from outside the sample receiving chamber 3 or to discharge it from there to outside the sample receiving chamber 3 via the filling fluid outlet line. The high-pressure viewing cell 1 usually has examination fluid lines 6, in particular in the form of a supply line and/or a discharge line, in order to supply an examination fluid via the examination fluid lines 6 during use from outside the sample receiving chamber 3 to a microfluid channel system of a microfluid chip 2 arranged with the holding device 4 in the sample receiving chamber 3 via an inlet of the microfluid chip 2 or to discharge it via an outlet of the microfluid chip 2 from the microfluid channel system to outside the sample receiving chamber 3. The examination fluid can be an oil, for example. As a rule, the filling fluid pressure and/or an examination fluid pressure of the examination fluid is greater than 100 bar during use. The high-pressure viewing cell can have a temperature control device 25 designed as a heating band, wherein the heating band contacts a sample receiving chamber wall of the sample receiving chamber on the outside in a heat-transferring manner in order to heat the respective fluid passed through the sample receiving chamber wall during use with the heating band.

[0039] The window element 5 is held by a window element holder 7, the window element 5 being tapered at least in sections in an external direction A of the window element 5 from an internal pressure side of the window element 5 to an external pressure side of the window element 5, so that a positive connection is formed between a support element 8 of the window element holder 7 and the window element 5. Fig. 4 shows a schematic representation of a window element 5 of the high-pressure viewing cell 1 of Fig. 1 held by the window element holder 7 in a cross section parallel to the external direction A of the window element 5. In the cross section through the window element 5 parallel to the external direction A of the window element 5, the window element 5 has at least in sections a tapered side contour representing the side surface 9 in the external direction A of the window element 5. The support element 8 has a through-channel 10 with a through-channel wall 11 designed to correspond in shape to the window element 5, wherein the window element 5 is inserted at least partially, preferably substantially entirely, into the through-channel 10 in the outward direction A, so that a positive connection is formed between the through-channel wall 11 and a side surface 9 of the window element 5. The through-channel wall 11 usually forms a stop for the side surface 9 in the outward direction A of the window element 5. Preferably, the window element 5 is at least partially, in particular

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mainly, preferably essentially, conical, with the side surface 9 being formed with a conical surface of the conical shape of the window element 5. The window element 5 usually has an external transparent surface 12 and an internal transparent surface 13, between which transparent surfaces 12, 13 the side surface 9 extends, usually circumferentially around the window element 5.

[0040] The window element 5 is usually inserted into the through-channel 10 in such a way that the window element 5, in particular the side surface 9 of the window element 5, is pressed against the through-channel wall 11. In this way, a fluid-tight connection can be formed between the window element holder 7 and the window element 5. The through-channel wall 11 can expediently have a pressing surface formed with a sealing material, wherein the side surface 9 is pressed against the pressing surface. Preferably, the pressing surface is formed with a sealing element 14, in particular a sealing ring, wherein the sealing element 14 is usually arranged so that it runs circumferentially along the side surface 9 around the window element 5. This applies in particular when viewed against the external direction A of the window element 5 on the window element 5. In this way, a fluid-tight pressing connection can be formed circumferentially around the window element 5 between the through-channel wall 11 and the side surface 9 of the window element 5. Preferably, the sealing element 14 is at least partially inserted in a form-fitting manner into a sealing element recess 15 of the through-channel wall 11 which corresponds in shape to the sealing element 14.

[0041] The window element holder 7 has an actuating device 16 in the form of a closure element 17 which is movable relative to the support element 8 and with which a pressing force is exerted on the window element 5 so that the window element 5, in particular the side surface 9 of the window element 5, is pressed against the through-channel wall 11, in particular the pressing surface. The closure element 17 usually forms a stop for the window element 5 against the outward direction A of the window element 5. It is advantageous if the closure element 17 is a threaded ring which is reversibly screwed into the through-channel 10 so that the window element 5 is detachably enclosed in the through-channel 10 with the threaded ring. The threaded ring closes the through-channel 10 for the window element 5, usually on a side of the window element 5 facing the sample receiving space 3. The threaded ring is usually screwed into the through-channel 10 in such a way that the threaded ring presses the window element 5 against the through-channel wall 11, in particular the pressing surface. The threaded ring usually applies a pressing force to a surface of the window element 5 facing the sample receiving space 3. The threaded ring is preferably essentially completely sunk into the through-channel 10. The threaded ring is usually detachably connected to the support element 8 and can be detached from the support element 8, in particular by unscrewing it from the through-channel 10.

[0042] For the detachable connection of the window element holder 7 to a basic structure of the high-pressure viewing cell 1, the window element holder 7 is pressed against the basic structure with a fastening element 18 to form a positive connection with the fastening element 18. The fastening element 18 can be connected to the basic structure with a screw connection. The fastening element 18 is preferably a fastening sleeve into which the window element holder 7 is at least partially inserted, in particular in a positive connection. By detaching the fastening element 18 from the basic structure of the high-pressure viewing cell 1, the window element holder 7 can be detached from the basic structure without detaching the connection between the window element holder 7 and the window element 5. The window element holder 7 can expediently have a stepped edge area with a step surface 19 on the outside, wherein the fastening element 18 has a projection 20, in particular designed to correspond in shape to the edge area, which projection 20 engages the step surface 19 in the outward direction A, forming a stop for the step surface 19. The window element holder 7 usually has a contact surface 21, which is pressed against a counter surface 22 of the basic structure. The contact surface 21 and/or the counter surface 22 can be formed with a sealing element 14, in particular a sealing ring, in order to create a fluid-tight connection between

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the contact surface 21 and the counter surface 22. The sealing element 14 can be inserted in a form-fitting manner, at least partially, into a recess in the contact surface 21 and/or the counter surface 22 that corresponds in shape to the sealing element 14. The sealing element 14 can run circumferentially around the window element 5 when viewed against the outward direction A of the window element 5.

[0043] The high-pressure viewing cell 1 can have several window element arrangements 23, each formed with a window element holder 7 and a window element 5 held by the latter, in particular on different sides of the sample receiving space 3. The window element holder 7 and the window element 5 of the respective window element arrangement 23 can be implemented as described in this document, in particular above. It is particularly advantageous if window element arrangements 23, in particular their window elements 5, are arranged on opposite sides of the sample receiving space 3. As a result, during use the microfluid chip 2 or a flow of the examination fluid in the microfluid channel system of the microfluid chip 2 can be irradiated with light through one of the window elements 5 and observed with a microscope through the other window element 5 opposite this on the sample receiving space 3.

Claims (13)

patent claims 1. High-pressure viewing cell (1) for optical observation of a microfluid chip (2), wherein the microfluid chip (2) can be arranged in a sample receiving space (3) of the high-pressure viewing cell (1), wherein the high-pressure viewing cell (1) has a window element (5) for observing the microfluid chip (2) through the window element (5) and a window element holder (7) for holding the window element (5), wherein in order to produce a connection, in particular a positive and/or non-positive connection, between the window element holder (7) and the window element (5), the window element (5) is tapered at least in sections from an internal pressure side of the window element (5) to an external pressure side of the window element (5), characterized in that the high-pressure viewing cell (1) has a holding device (4) in the sample receiving space (3) for the, in particular detachable, arrangement of the microfluid chip (2) in order to supply an examination fluid to a Microfluid channel system of the microfluid chip (2), wherein the holding device (4) has a chip carrier in order to arrange the microfluid chip (2) on the holding device, and is designed, during use, to arrange the microfluid chip (2) in the sample receiving space (3) in such a way that the microfluid chip (2) can be subjected to a filling medium pressure of a filling medium with which the sample receiving space (3) can be filled, from an upper side and an underside of the microfluid chip (2). 2, High-pressure viewing cell (1) according to claim 1, characterized in that the window element holder (7) positively delimits the window element (5) on a side surface (9) of the window element (5), which side surface (9) runs between an inner transparent surface (13) facing the sample receiving space (3) and an outer transparent surface (12) of the window element (5) located outside the sample receiving space. 3. High-pressure viewing cell (1) according to claim 2, characterized in that the side surface (9) is designed at least in sections as a rotational surface, in particular a conical surface, tapering in the outward direction (A) of the window element (5). 4. High-pressure viewing cell (1) according to claim 2 or 3, characterized in that the window element holder (7) forms a through-channel (10) into which the window element (5) is at least partially inserted, so that the side surface (9) is pressed against a through-channel wall (11) forming the through-channel (10). 5. High-pressure viewing cell (1) according to one of claims 2 to 4, characterized in that the window element holder (7) has a pressing surface, in particular formed with an elastically and/or plastically deformable sealing element (14), wherein the side surface (9) is pressed against the pressing surface in order to implement a fluid-tight press connection. 6. High-pressure viewing cell (1) according to one of claims 1 to 5, characterized in that the window element holder (7) has an actuating device (16) in order to press the window element (5) against the window element holder (7) and/or to change a pressing force between the window element (5) and the window element holder (7) upon actuation of the actuating device (16). 7. High-pressure viewing cell (1) according to claim 6, characterized in that the actuating device (16) forms a movable stop for a surface of the window element (5) facing a sample receiving space (3) of the high-pressure viewing cell (1). 8. High-pressure viewing cell (1) according to one of claims 1 to 7, characterized in that the window element holder (7) is detachably connected to a basic structure of the high-pressure viewing cell (1), wherein the window element holder (7) is detachable from the basic structure without releasing the connection between the window element holder (7) and the window element (5). 9. High-pressure viewing cell (1) according to one of claims 1 to 8, characterized in that the window element holder (7) is detachably connected to a basic structure of the high-pressure viewing cell (1), wherein the window element holder (7) is secured against a counter surface (22) of the basic structure by a fastening element (18) circumferentially surrounding the window element holder (7). structure, wherein in particular a pressing force exerted by the fastening element (18) on the window element holder (7) can be changed by screwing in the fastening element (18). 10. High-pressure viewing cell according to one of claims 1 to 9, characterized in that the high-pressure viewing cell (1) has at least one supply line in order to supply, during use, examination fluid to a microfluidic chip (2) arranged with the holding device (4) from outside the sample receiving chamber (3) via a fluid inlet of the microfluidic chip via the supply line, and/or has at least one discharge line in order to discharge examination fluid from the microfluidic chip (2) arranged with the holding device (4) via a fluid outlet of the microfluidic chip to outside the sample receiving chamber (3) via the discharge line. 11. High-pressure viewing cell (1) according to one of claims 1 to 10, characterized in that the high-pressure viewing cell (1) has an inlet line for supplying filling medium into the sample receiving chamber (3) and/or an outlet line for removing filling medium from the sample receiving chamber (3). 12. High-pressure viewing cell (1) according to one of claims 1 to 11, characterized in that the high-pressure viewing cell (1) has a temperature control device in order to temperature control, in particular to heat and/or cool, fluid which is supplied to or is supplied to the sample receiving chamber (3) when used with the temperature control device. 13. High-pressure viewing cell (1) according to one of claims 1 to 12, characterized in that the high-pressure viewing cell (1) has a plurality of window element arrangements (23), wherein the respective window element arrangement (23) comprises a window element holder (7) and a window element (5) held by the window element holder (7), wherein the window element arrangements (23) are arranged on different, in particular mutually opposite, sides of the sample receiving space (3). Here 2 sheets of drawings