Implants in the form of wrap-around cuff electrode assemblies

Abstract

The invention relates to a medical implant in the form of a wound cuff electrode assembly, also referred to as a cuff electrode, comprising a flexible, biocompatible, membrane-like carrier substrate in the form of a tube having a certain length in a first region, formed by winding around a winding axis, the tube comprising a straight cylindrical cavity delimited radially relative to the winding axis by a surface of the carrier substrate, at least one electrode surface being mounted on the carrier substrate, the at least one electrode surface being connected to a non-flexible contact assembly via at least one electrical line integrated in the carrier substrate, the at least one electrical line being connected to a power supply and / or discharge line on the non-flexible contact assembly, resulting in an implantable power supply unit formed separately from the implant. The invention is characterized in that the contact assembly has a spatial longitudinal extension oriented parallel to the winding axis; the contact assembly is firmly bonded to the carrier substrate along a dimensionally stable connection region, the connection region having a connection region length oriented parallel to the winding axis (5); and the contact assembly overlaps the first region of the carrier substrate wound to form the tube in orthographic projection relative to the winding axis.

Description

Technical Field

[0001] The present invention relates to a medical implant in the form of a wound cuff electrode assembly, also referred to as a cuff electrode, which is suitable for use as an extravascular or extraneural attachment along a blood vessel or nerve fiber bundle in the body. The medical implant comprises a flexible, biocompatible, membrane-like carrier substrate, which in a first region is in the form of a tube having a certain length, formed by winding around a winding axis. The tube comprises a straight cylindrical cavity, which is radially delimited by the surface of the carrier substrate relative to the winding axis. At least one electrode surface is mounted on the carrier substrate, and the at least one electrode surface is connected to a non-flexible contact assembly via at least one wire integrated in the carrier substrate. The at least one wire is connected to a power supply and / or discharge line on the non-flexible contact assembly, which leads to an implantable power supply unit formed separately from the implant. Background Art

[0002] Cuff electrodes of the aforementioned type are typically used to record electrical signals from internal blood vessels and also to apply electrical signals to internal blood vessels, particularly to nerve bundles. To this end, the cuff electrode comprises a flexible, biocompatible carrier substrate, with at least one electrode, preferably multiple electrodes, applied to the surface of the carrier substrate facing the nerve bundle. The electrodes must be connected in close physical contact with the surface of the nerve bundle.

[0003] WO 2016 / 055512 A1 discloses a cuff electrode of this type. The carrier substrate of the cuff electrode comprises a polyimide film that has been mechanically pre-tensioned for the purpose of at least partially automatic winding around a winding axis. By winding the cuff electrode around a nerve bundle, the individual electrodes of the cuff electrode come into direct surface contact with the epineurium of the nerve fiber bundle. The cuff electrode attaches itself to the nerve fiber bundle via a force-loaded, mating connection, with the carrier substrate areas that have overlapped due to the curling or winding process resting against each other in a loose, sliding manner.

[0004] Each of the wires leading from a single electrode of the cuff electrode extends electrically insulated within the polyimide film and terminates at a side edge region of the polyimide film, which is spatially separated from the winding region of the cuff electrode, and through an electrical contact assembly, each of the ends of the wires on the side edge region is connected to a power supply and discharge line, and the cuff electrode is connected to an implantable power supply unit via the power supply and discharge line, which is located in the body and separated from the cuff electrode.

[0005] On the one hand, due to the natural sensitivity of nerve fibers to external mechanical influences, the mechanical load acting on the nerve fiber bundle must be kept as low as possible. On the other hand, it must be ensured that the cuff electrode surrounds the nerve fiber bundle sufficiently stably to ensure that the cuff electrode is as durable as possible and is connected as firmly as possible along the nerve fiber bundle.

[0006] Practical experience with cuff electrodes has shown that, on the one hand, the loose winding of the carrier substrate (sometimes distributed in multiple layers around the nerve fiber bundle) allows the cuff electrode to dynamically expand radially, thereby allowing the cuff electrode to adapt to the natural changes in the shape of the nerve fiber bundle. On the other hand, external forces acting on the cuff electrode can significantly change its winding geometry, with the result that the nerve fiber bundle may be subjected to considerable mechanical stress, leading to irreversible damage.

[0007] DE 4433111 A1 describes a cuff electrode comprising a flexible, multilayer substrate made of non-conductive silicone, on which a raised electrode made of conductive silicone is attached. Conductor paths to the electrodes extend between the non-conductive layers and are also made of conductive silicone. The cuff electrode's rolled-up form is achieved by applying different bias voltages within the cuff's multilayer structure. Summary of the Invention

[0008] The present invention is directed to further developing a cuff electrode comprising a flexible, biocompatible, membrane-like carrier substrate, which in a first region is formed into a tube by being wound around a winding axis, the tube comprising a straight cylindrical cavity radially delimited relative to the winding axis by the surface of the carrier substrate, at least one electrode surface being mounted on the carrier substrate, the electrode surface being connected to a non-flexible contact assembly via at least one electrical line integrated into the carrier substrate, the at least one electrical line being connected to a current supply and / or discharge line, which leads to an implantable current supply unit formed separately from the implant, in such a way that the force or pressure exerted by the cuff electrode on the nerve fiber bundle is ensured to be as uniform and gentle as possible in the simplest manner. This is particularly true when the cuff electrode is subjected to tensile forces along the current supply and / or discharge line, which may be caused, for example, by movements of the human body itself.

[0009] The solution to the object underlying the invention is set forth in claim 1. Features further contributing to the solution concept are the subject matter of the dependent claims and can also be found in the accompanying description.

[0010] According to this solution, the medical implant designed in the form of a wound cuff electrode assembly according to the features of the guide section of claim 1 is characterized in that the contact assembly is firmly bonded to the carrier substrate along a dimensionally stable connection region. The connection region has a spatial length oriented parallel to the winding axis, wherein the contact assembly, orthogonally projected relative to the winding axis, overlaps with a first region of the carrier substrate wound to form a tube.

[0011] The design of the cuff electrode according to the invention involves a special design and application of a contact assembly relative to a carrier base region of the cuff electrode, which is in the form of a tube by a rolling or winding process and which in the implanted state locally surrounds a bundle of nerve fibers, based on the experience gained with the known cuff electrode according to WO 2016 / 055512 A1. In the known cuff electrode, the region of the membrane-like carrier base which is directly and integrally adjacent to the first region of the carrier base wound to form a tube is essentially band-shaped or strip-shaped. All electrical wires connected to the electrodes of the cuff electrode extend along the band-shaped carrier base region. The band-shaped carrier base region has a longitudinal extent oriented essentially parallel to the winding axis and is connected to the carrier base region wound into the tube locally in the center by a narrow band portion bent at right angles. In the event of a tensile or thrust force acting along the band-shaped carrier base oriented parallel to the winding axis, symmetrical forces are exerted on the carrier base region wound into the tube. Along the winding axis, on one side of the wound carrier substrate, the pressure environment generated may lead to tighter winding and associated contraction, while on the opposite side of the wound carrier substrate area, it leads to expansion and associated local unwinding, so that the intrinsic nerve bundles are subjected to significant abnormal pressure or mechanical effects.

[0012] According to an embodiment of the solution, such asymmetric stress conditions acting on the nerve bundle are avoided on the one hand, since the contact device made of a non-flexible material (e.g. ceramic) acts as a force coupler, which transmits the tensile and / or thrust forces acting along the supply and / or discharge lines as evenly as possible to the region of the carrier base wound to form the tube and applies them in a grid-like manner around the nerve fiber bundle. As a result, asymmetric winding geometries with a smaller diameter at one end of the tube and a larger diameter at the other end are avoided. The force transmission preferably takes place via the contact assembly along the entire axial length of the tube to the region of the carrier base wound to form the tube. In this way, any shear forces acting on the nerve bundle can be avoided. Preferably, the contact assembly and the carrier base are connected by a connection region, which has a connection region length oriented parallel to the winding length and which corresponds at most to the mutual overlap between the contact assembly and the tube in an orthographic projection relative to the winding axis. It is particularly advantageous in this regard if the longitudinal length of the contact assembly is equal to or greater than the tube length.

[0013] Examples of embodiments are also conceivable in which the dimensions of the longitudinal extension of the contact assembly, the tube length and the connection area length differ from one another, but in these cases it must advantageously be ensured that the contact assembly is securely connected relative to the carrier substrate such that the longitudinal extension of the contact assembly, the tube length and the connection area length all have a common center axis that is orthogonal to the winding axis.

[0014] Preferably, the contact assembly comprises a plate-like carrier, on which at least one electrical wire on the cuff electrode side is contacted, preferably via microelectrical contacts, to an electrode applied to the carrier. The carrier-side electrode is in turn connected to another electrode surface, separately applied to the carrier, to which a power supply and / or discharge line leading to an independent power supply unit is electrically connected via welding, soldering, or adhesive bonding. Naturally, a plurality of such electrode / electrode surface pairs may be present on the plate-like carrier, via which a corresponding number of electrical wires on the cuff electrode side are connected to corresponding power supply and / or discharge lines assembled into a cable strand.

[0015] One or more power supply and / or discharge wires combined into a cable strand and a plate-shaped carrier are surrounded by an elastic material, which is connected to the carrier base in a fluid-tight manner in the connection area. The elastic material surrounding at least one power supply and / or discharge wire in a fluid-tight, hose-like or matrix-like manner is formed into a bundle shape with a longitudinal extension, the length of which is determined according to the individual positions of the cuff electrode and the supply unit in the body. The carrier length of the plate-shaped carrier is much greater than its carrier width, and its longitudinal extension is oriented parallel to the winding axis. The relatively narrow carrier shape is preferably sized so that it can be embedded in the bundle along which the at least one power supply and / or discharge wire is integrated without or without any substantial shape change. Specific embodiments are described in more detail below.

[0016] In a preferred embodiment, for the purpose of additional force distribution of the forces acting on the nerve fiber bundle via the cuff electrode, at least one additional fastening device is applied adjacent to the cuff electrode along the bundle or tube containing at least one power supply and / or discharge line, the fastening device being in the form of a wound cuff or spiral structure. The additional fastening device comprises a straight cylindrical cavity like the cuff electrode, which is coaxially aligned with the winding axis.

[0017] In another preferred embodiment, in the longitudinal extension of the bundle, the bundle or tube provides a bundle extension adjacent to the contact assembly, on which a second fastening device of the type described above as the first fastening device is formed and applied. In this way, tensile and / or thrust forces acting along the supply and / or discharge lines can be deflected or transferred symmetrically along the nerve bundle relative to the force electrode assembly.

[0018] All electrical conductor structures applied on the carrier substrate, including at least one electrode surface and at least one electrical wire electrically connected to the electrode surface, are preferably made integrally by a metal deposition process, so that there are no connection points and associated discontinuous electrical impedance differences along the electrical conductor structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will now be described by way of example with reference to the accompanying drawings, without limiting the general inventive concept, in which:

[0020] Figure 1 An example of an embodiment of a medical implant designed according to the solution is shown. DETAILED DESCRIPTION

[0021] Figure 1 A cuff electrode 1 is shown, which is configured in the style of a wound cuff electrode assembly with a membranous carrier substrate 2, which is preferably made of a polyimide film. The carrier substrate 2 comprises two regions 3, 4 that are completely connected, and the first region 3 of the carrier substrate 2 is wound around a winding axis 5. The first region 3 of the carrier substrate 2 wound into the tube maintains its wound shape due to the inherent tensile force of the material itself, which is applied by appropriately treating the membranous carrier substrate 2 (for example by heat treatment), and the first region 3 comprises a straight cylindrical cavity 6, which is axially open on both sides. At least one electrode surface 7, preferably a plurality of such electrode surfaces, is applied to the surface of the tubular wound first region 3 of the carrier substrate 2 facing the straight cylindrical cavity 6, each surface being in direct physical contact with the outer wall of the nerve fiber bundle not shown in detail. Each electrode surface 7 is integral with an electrical wire 8, and all electrical wires 8 extend in an electrically insulated manner within the carrier substrate 2.

[0022] The second region 4 of the carrier substrate 2 integrally adjoins the first region 3 of the carrier substrate 2, the second region 4 having a side edge 9 facing away from the first region 3, along which the electrical wires 8 terminate adjacent to one another and, via microelectrical contacts 10, respectively contact electrodes attached to a contact assembly 11. The contact assembly 11 is configured as a plate-shaped carrier 12, preferably comprising a ceramic disk, and having a longitudinal extension 13. The length of the carrier 12 is much greater than its width.

[0023] Electrodes attached to the plate-like carrier 12 connect each of the electrical wires 8 to an electrical contact surface 14 on top of the plate-like carrier 12, on which the supply and / or discharge wires 15 are electrically contacted by means of a soldered, adhesive or welded connection. Figure 1 All power supply and discharge lines 15 connected to the respective contact surfaces 14 are combined into a cable strand 15 * , which leads to a power supply unit 16 formed separately from the cuff electrode 1, which provides, for example, control signals and electrical energy for operating the cuff electrode 1. In order to separately operate the supply unit 16, for example for replacement, the cable strands 15 are assembled together by means of a fluid-tight plug connection (not shown). * The linear power supply and discharge wires 15 are connected to the power supply unit 16. For electrical insulation and to prevent the humid internal environment, the cable strands 15 including all power supply and / or discharge wires 15 are * Surrounded by a silicone tube 17 or embedded in a silicone bundle 17 .

[0024] In order to ensure that the tensile or thrust forces 18 acting along the silicone strands 17 are distributed as evenly as possible over the entire length 19 of the first region 3 of the carrier substrate 2 wound to form the tube, in the connection region 20 between the contact assembly 11 and the second region 4 of the carrier substrate 2, the carrier substrate 2 is joined to the surface of the plate-shaped carrier 12 of the contact assembly 11 by a firm connection, e.g. Figure 1 As shown, the connection region 20 is arranged at least partially, preferably completely orthographically, relative to the winding axis 5, overlapping with the axial extension 19 of the region 3 of the carrier substrate 2 wound to form the tube. Regardless of the actual dimensions of the individual lengths of the contact assembly 11, the connection region 20 and the first region 3 of the carrier substrate 2 wound to form the tube, the longitudinal extension (13) of the contact assembly 11, the tube length (19) and the connection region length (21) preferably have a common middle axis (24) oriented orthogonally relative to the winding axis (5).

[0025] exist Figure 1 In the embodiment, the connection region 20 has a longitudinal extension 21 that corresponds approximately to the length 19 of the region 3 of the carrier substrate 2 wound to form the tube. In this case, the contact assembly 11 transmits force uniformly to the carrier substrate 2 via the connection region 20 over the entire length 19.

[0026] Optionally, fastening means 22, 22' can be provided along the winding axis 5 on one side of the cuff electrode 1 or on both sides of the cuff electrode 1, similar to how the cuff electrode 1 can be arranged around the periphery of the nerve bundle under the action of force. The fastening means 22, 22' can be in the form of a wrapped cuff or a known spiral structure, which is preferably made of silicone material. The fastening means 22 on the left side of the figure is applied directly to the silicone bundle 17 via a connection 23. The connection 23 is preferably designed as an integral connection, that is, the fastening means 22, the connection 23 and the silicone bundle 17 are made of the same material as part of the same manufacturing process. The connection 23 can be configured in the form of a seamless transition between the silicone bundle 17 and the fastening means 22, up to a special connection geometry, such as a straight, zigzag, spiral or spiral connecting arm. A fastening means 22' is also optionally provided on the right side of the cuff electrode 1, which is applied to the bundle extension 17'. In this case, the connection 23' can also be designed in the same way as described above.

[0027] Reference Signs List

[0028] 1 Cuff electrode

[0029] 2 Carrier substrate

[0030] 3. First region of the carrier substrate

[0031] 4 Second area of the carrier substrate

[0032] 5 Winding axis

[0033] 6 straight cylindrical cavity

[0034] 7 Electrode surface

[0035] 8 wires

[0036] 9 Connecting end edge of carrier substrate

[0037] 10 Micro-electric contacts

[0038] 11 Contact assembly

[0039] 12 Plate carrier

[0040] 13 Longitudinal extension of the contact assembly

[0041] 14 Electrode surface

[0042] 15 Power supply and / or discharge

[0043] 15 * Cable strands

[0044] 16 Power supply unit

[0045] 17 Silicone Bundle

[0046] 17' beam extension

[0047] 18 Push and pull forces

[0048] 19 Length of the second region 3 of the carrier substrate wound to form a tube

[0049] 20 connection area

[0050] 21 Connection area length

[0051] 22, 22' fastening device

[0052] 23, 23' connection

[0053] 24 Middle axis

Claims

1. A medical implant in the form of a wound cuff electrode assembly, referred to as a cuff electrode (1), comprising a flexible, biocompatible and membrane-like carrier substrate (2), which in a first region (3) is wound around a winding axis (5) to take on the shape of a tube with a tube length (19), the tube comprising a straight cylindrical cavity (6) which is delimited radially relative to the winding axis (5), at least one electrode surface (7) being applied to the straight cylindrical cavity (6), by means of a to At least one electrical wire (8) connects the electrode surface (7) to a non-flexible contact assembly (11), on which the at least one electrical wire (8) is connected to a power supply and / or discharge line (15), which leads to an implantable power supply unit (16) formed separately from the implant, wherein a first region (3) of the carrier substrate (2) wound to form a tube has at least one winding around a winding axis, the winding having at least one winding region in which the carrier substrate (2) is loosely overlapped radially relative to the winding axis (5), It is characterized by: The contact assembly (11) has a spatial longitudinal extension (13) oriented parallel to the winding axis (5), the contact assembly (11) is firmly bonded to the carrier substrate (2) along a dimensionally stable connection region (20), the connection region (20) having a connection region length (21) oriented parallel to the winding axis (5), and the connection region (20) overlaps in orthographic projection with the axial extension of the first region (3) of the carrier substrate (2) wound to form a tube, wherein the connection region length (21) of the connection region (20), the longitudinal extension (13) of the contact assembly (11) and the axial extension of the first region (3) have a common intermediate axis (24) oriented orthogonally with respect to the winding axis (5); The contact assembly (11) has a plate-shaped carrier (12), on which at least one electric wire (8) is contacted via a micro-electrical contact, said micro-electrical contact being electrically connected to an electrode (14) applied to the plate-shaped carrier (12), and a power supply and / or discharge wire (15) being electrically connected to the electrode (14); and The current supply and / or discharge line (15) and the plate-shaped carrier (12) are surrounded by an elastic material, which is connected to the carrier substrate (2) in a fluid-tight manner in a connection region (20).

2. The medical implant according to claim 1, It is characterized by: The contact assembly (11) is arranged relative to the carrier substrate (2) in such a way that the longitudinal extension (13) of the contact assembly (11) and the tube length (19) of the first region (3) of the carrier substrate (2) wound to form the tube overlap maximally in orthographic projection relative to the winding axis (5).

3. The medical implant according to claim 1 or 2, It is characterized by: Between the contact assembly (11) and the carrier substrate (2), the connection region (20) has a connection region length (21) oriented parallel to the winding axis (5), and in orthographic projection relative to the winding axis (5), the connection region length (21) corresponds at most to the common overlap of the longitudinal extension (13) of the contact assembly (11) and the tube length (19).

4. The medical implant according to claim 1, It is characterized by: The contact assembly (11) is securely connected relative to the carrier substrate (2) such that the longitudinal extension (13), the tube length (19), and the connection region length (21) of the contact assembly (11) each have a common intermediate axis (24) oriented orthogonally relative to the winding axis (5).

5. The medical implant according to claim 1, It is characterized by: The carrier substrate (2) has a second flat carrier substrate area (4) adjacent to the first area (3) wound to form a tube, the second flat carrier substrate area (4) having a side edge (9) laterally delimiting the carrier substrate (2), and on the second flat carrier substrate area (4), at least one electrical wire (8) is electrically connected to the contact assembly (11) in a connection area (20).

6. The medical implant according to claim 1, It is characterized by: The elastic material surrounding at least one current supply and / or discharge wire (15) is in the form of a bundle (17) having a bundle longitudinal extension, which is oriented parallel to the winding axis (5) at least in a region immediately adjacent to the contact assembly (11), and a first fastening device (22) comprising a straight cylindrical cavity is applied directly or indirectly in the region of the bundle (17) containing the at least one current supply and / or discharge wire (15) in the form of a wound cuff or spiral structure, the straight cylindrical cavity being oriented coaxially with respect to the winding axis (5).

7. The medical implant according to claim 6, It is characterized by: In its longitudinal extension, the bundle (17) provides a bundle extension (17') opposite the contact assembly (11), on which second fastening means (22') of the type of the first fastening means (22) are applied directly or indirectly.

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