IMPLANTABLE ELECTRODE CONFIGURATION

Abstract

The invention is an implantable electrode configuration having a carrier substrate of a biocompatible polymer in at least some areas and a freely accessible electrode surface applied to the carrier substrate or integrated into the carrier substrate on the carrier substrate surface in at least some areas is described and a method for producing the implantable electrode configuration. The electrode has a metallic base plate having a planar top side and bottom side, including at least one structural element protruding orthogonally from the top side. The planar surface of the metallic base plate is oriented parallel to the carrier substrate surface and the metallic base plate is enclosed by the biocompatible polymer, except for a first surface area of the at least one structural element which faces the carrier substrate surface and is the freely accessible electrode surface.

Claims

1-11. (canceled)

12. An implantable electrode configuration having a carrier substrate comprising a biocompatible polymer located in at least part of the substrate in which an accessible electrode surface of an electrode is applied to the carrier substrate or is integrated into the carrier substrate in at least part of the carrier substrate surface, comprising: a metallic base plate having a planar surface with a top side and bottom side, at least one structural element protruding relative to the top side and the planar surface of the metallic base plate being oriented parallel to the carrier substrate surface; and wherein the metallic base plate is enclosed by the biocompatible polymer, except for a first surface area of the at least one structural element which is oriented to face the carrier substrate surface and corresponds to the accessible electrode surface.

13. The electrode configuration according to claim 12, comprising: an adhesion promotion layer located at least between the bottom side of the metallic base plate and the biocompatible polymer of the carrier substrate.

14. The electrode configuration according to claim 12, comprising: the at least one structural element is connected in one piece to the metallic base plate.

15. The electrode configuration according to claim 13, comprising: the at least one structural element is connected in one piece to the metallic base plate.

16. The electrode configuration according to claim 12, comprising: identical structural elements located on the top side of the metallic base plate in a geometric pattern.

17. The electrode configuration according to claim 13, comprising: identical structural elements located on the top side of the metallic base plate in a geometric pattern.

18. The electrode configuration according to claim 14, comprising: identical structural elements located on the top side of the metallic base plate in a geometric pattern.

19. The electrode configuration according to claim 15, comprising: identical structural elements located on the top side of the metallic base plate in a geometric pattern.

20. The electrode configuration according to claim 12, wherein: the at least one structural element is one of columns, ribs, sleeves or webs.

21. The electrode configuration according to claim 13, wherein: the at least one structural element is one of columns, ribs, sleeves or webs.

22. The electrode configuration according to claim 14, wherein: the at least one structural element is one of columns, ribs, sleeves or webs.

23. The electrode configuration according to claim 15, wherein: the at least one structural element is one of columns, ribs, sleeves or webs.

24. The electrode configuration according to claim 16, wherein: the at least one structural element is one of columns, ribs, sleeves or webs.

25. The electrode configuration according to claim 17, wherein: the at least one structural element is one of columns, ribs, sleeves or webs.

26. The electrode configuration according to claim 18, wherein: the at least one structural element is one of columns, ribs, sleeves or webs.

27. The electrode configuration according to claim 19, wherein: the at least one structural element is one of columns, ribs, sleeves or webs.

28. The electrode configuration according to claim 12, wherein: the at least one structural element includes a longitudinal extension oriented orthogonal to the top side of the metallic base plate, along the longitudinal extension the at least one structural element has at least one web which protrudes orthogonal relative to the longitudinal extension and includes a second surface area parallel to the top side of the metallic base plate and to which an adhesion promotion layer is applied thereto; and the second surface area is separated from the first surface area and is surrounded by the biocompatible polymer.

29. The electrode configuration according to claim 13, comprising: the at least one structural element includes a longitudinal extension oriented orthogonal to the top side of the metallic base plate, along the longitudinal extension the at least one structural element has at least one web which protrudes orthogonal relative to the longitudinal extension and includes a second surface area parallel to the top side of the metallic base plate and to which an adhesion promotion layer is applied thereto; and the second surface area is separated from the first surface area and is surrounded by the biocompatible polymer.

30. The electrode configuration according to claim 14, comprising: the at least one structural element includes a longitudinal extension oriented orthogonal to the top side of the metallic base plate, along the longitudinal extension the at least one structural element has at least one web which protrudes orthogonal relative to the longitudinal extension and includes a second surface area parallel to the top side of the metallic base plate and to which an adhesion promotion layer is applied thereto; and the second surface area is separated from the first surface area and is surrounded by the biocompatible polymer.

31. The electrode configuration according to claim 20, comprising: the at least one structural element includes a longitudinal extension oriented orthogonal to the top side of the metallic base plate, along the longitudinal extension the at least one structural element has at least one web which protrudes orthogonal relative to the longitudinal extension and includes a second surface area parallel to the top side of the metallic base plate and to which an adhesion promotion layer is applied thereto; and the second surface area is separated from the first surface area and is surrounded by the biocompatible polymer.

32. The electrode configuration according to claim 28, wherein: the second surface area faces away from the carrier substrate surface.

33. The electrode configuration according to claim 29, wherein: the second surface area faces away from the carrier substrate surface.

34. The electrode configuration according to claim 30, wherein: the second surface area faces away from the carrier substrate surface.

35. The electrode configuration according to claim 31, wherein: the second surface area faces away from the carrier substrate surface.

36. The electrode configuration according to claim 12, wherein: the base plate has a thickness ranging between 10 nm and 5 μm, and the at least one structural element has a length at a location above the base plate ranging between 50 nm and 5 μm.

37. The electrode configuration according to claim 13, wherein: the base plate has a thickness ranging between 10 nm and 5 μm, and the at least one structural element has a length at a location above the base plate ranging between 50 nm and 5 μm.

38. The electrode configuration according to claim 14, wherein: the base plate has a thickness ranging between 10 nm and 5 μm, and the at least one structural element has a length at a location above the base plate ranging between 50 nm and 5 μm.

39. The electrode configuration according to claim 16, wherein: the base plate has a thickness ranging between 10 nm and 5 μm, and the at least one structural element has a length at a location above the base plate ranging between 50 nm and 5 μm.

40. The electrode configuration according to claim 20, wherein: the base plate has a thickness ranging between 10 nm and 5 μm, and the at least one structural element has a length at a location above the base plate ranging between 50 nm and 5 μm.

41. The electrode configuration according to claim 28, wherein: the base plate has a thickness ranging between 10 nm and 5 μm, and the at least one structural element has a length at a location above the base plate ranging between 50 nm and 5 μm.

42. The electrode configuration according to claim 32, wherein: the base plate has a thickness ranging between 10 nm and 5 μm, and the at least one structural element has a length at a location above the base plate ranging between 50 nm and 5 μm.

43. The electrode configuration according to claim 12, wherein: the carrier substrate has a thickness oriented orthogonal to the carrier substrate surface and the base plate is centrally located relative to the substrate thickness.

44. A method for producing a implantable electrode configuration according to claim 12, comprising: applying a metallic base plate to a carrier substrate of the biocompatible polymer; applying monolithically at least one structural element which extends orthogonally from the top side of the base plate; and applying the biocompatible polymer to the carrier substrate and the base plate so that the at least one structural element, except for a first surface area of the at least one structural element, is oriented to face away from the top side of the base plate and is completely surrounded by the biocompatible polymer.

45. The method according to claim 46, comprising: depositing the at least one structural element by a vapor deposition or sputtering.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The invention is described below on the basis of exemplary embodiments without restricting the general idea of the invention, with reference to the drawings, in which:

[0016] FIG. 1a shows a detailed diagram of an electrode integrated into the carrier substrate;

[0017] FIG. 1b shows an alternative design of a structural element; and

[0018] FIG. 2 shows sequential diagrams for the production of the implantable electrode configuration.

DETAILED DESCRIPTION OF THE INVENTION

[0019] To permanently improve the joining of an electrode body 2, for example, in the form of an electrode strip in or on a carrier substrate 1 made of a biocompatible polymer material, it is proposed that the electrode strip 3 be integrated extensively into the carrier substrate 1 in the following manner as shown in FIG. 1a.

[0020] The electrode body 2 has a metallic base plate 3, which has a top side 31 and a bottom side 32. Orthogonally elevated structural elements 4 are connected in one piece to the top side 31 of the base plate 3 and are preferably distributed over the entire area of the top side. These structural elements preferably are in the form of protrusions shaped like columns, ribs, webs or sleeves, over a surface area 41 facing the carrier substrate surface 1′ as shown in FIG. 1a, which can come into direct contact with the epineurium, for example, of a nerve fiber bundle in the implanted state of the electrode configuration. In addition, an adhesion promotion layer 5 is advantageously provided at least between the bottom side 32 and the polymer material of the carrier substrate 1 surrounding the base plate 3 as seen in FIG. 1b, which shows enlarged detail of the implantable electrode configuration diagrammed in FIG. 1a.

[0021] Furthermore, the adhesion promotion layer 3 may also be applied to the top side 31 of the base plate 3. Especially suitable adhesion promoter layers are silicon carbide (SiC) and diamond-like carbon (DLC). The electrode bodies 2, in particular in the area of the structural elements 3, preferably contain iridium oxide, which is one of the materials having the highest charge transfer capacities.

[0022] Basically, any number and configuration of individual structural elements 4 may be selected, but constellations KO arranged geometrically, such as square, pentagonal, hexagonal or higher-order configuration patterns, are also suitable, as for example, those shown in FIG. 1a.

[0023] A further improved variant of the at least one structural element 4 is illustrated in FIG. 1c. FIG. 1c shows a longitudinal section through a structural element 4, which has a longitudinal extension LA oriented orthogonally to the top side 31 of the metallic base plate 3. The structural element 4 has, along the longitudinal extension, at least one lateral protrusion 42 having an extension oriented orthogonally to the longitudinal axis LA.

[0024] The protrusion 42 has a second surface area 43, which is oriented parallel to the top side 31 of the metallic base plate 3 and faces it. In a first variant, the adhesion promotion layer 5 or an adhesion promotion layer configuration 5′ is applied to the second surface area 43 and is also provided on the bottom side 32 as in the present case. The second surface area 43 is disposed at a distance from the first surface area 31 and is completely surrounded by the biocompatible polymer while separated by the adhesion promotion layer (5) and/or the adhesion promotion layer configuration (5′).

[0025] In a second variant, at least one of the adhesion promotion layer (5) and the adhesion promotion layer configuration (5′) is additionally applied to the top side 44 of the protrusion 42, which is shaped as a web and is preferably also applied to the top side 31 of the base plate 3. To produce the at least one electrode 2 according to the invention, which is inserted into the biocompatible polymer material, the process steps are explained with reference to the sequential images a through ab.

[0026] A polyimide layer PI is applied in a uniform distribution to the surface of a silicon wafer Wa that is supplied at step a by spin coating at step b. Then a photoresist Fl at step c is applied to the polyimide layer Pl which is next exposed with the help of a mask and developed for the purpose of structuring the photoresist Fl as seen at step d. In the next step, an adhesion promoter layer HV is applied over the entire area, as for example, by a vapor deposition technique deposited there. DLC, for example, is suitable for this purpose. Metallization over the entire surface area is performed with step f, preferably with platinum Pt, which is deposited on the adhesion promotion layer HV a sputtering or vapor deposition processes. The base plate 3 of the electrode identified above is created in this way. A lift-off process is carried out at the next step g, in which all the material layers are removed except for the structured platinum base plate Pt, which is applied to the polyimide layer Pl with the adhesion promotion layer HV on the bottom side.

[0027] An adhesion promotion layer HV is applied again in step h. Then a second polyimide layer PI is deposited by spin coating at step i. In step j, a photoresist layer Fl is applied again by spin coating. Next, the photoresist layer Fl is exposed and developed by using a mask at step k. Then in the next step 1, the photoresist layer Fl is removed locally down to the top adhesion promotion layer by dry plasma etching in the area of the opened photoresist layer.

[0028] In step m, an Ir-IrOx layer is applied again. In step n, the structured photoresist layer Fl is extracted by a lift-off process. In the next step o, a photoresist layer Fl is applied. In step p, this photoresist layer Fl is developed and etched down to the level of the Ir-IrOx layer. It should be pointed out that the opening exceeds the width of the Ir-IrOx area of the electrode as seen at step p. An adhesion promotion layer HV is applied again at step q. At step r, a third metallization is performed by at least one of sputtering and vapor deposition. In this step, iridium Ir is deposited with an increasing amount of iridium oxide IrOx in the direction vertically upward. In the next step s, an HV layer is applied again. In step t, a lift-off process is again performed at in which the metal layer applied to the polyimide surface is locally removed.

[0029] Large-area deposition of a polyimide layer Pl then takes place by spin coating at process step u. In the following step v, this layer is covered with a photoresist layer Fl, which is then exposed and developed using a mask in step w, so that a local opening is formed within the photoresist layer. In the next step x, Ir-IrOx is again applied by sputtering to form the protrusion 42 identified above. A lift-off process takes place in process step y, followed by step z, in which a photoresist layer Fl is applied by spin-coating.

[0030] In step aa), these photoresist Fl is developed by using a mask. Two trenches extending to the surface of the silicon wafer Wa are exposed by dry etching. In the last step ab), the photoresist layer Fl is removed, which creates an implantable electrode configuration providing an electrode body 2, which is covered almost completely by polyimide. The electrode body has a base plate 3 made of platinum and a web-type protrusion 4 having a top electrode surface 41 which is freely accessible as shown by the enlarged diagram in FIG. 2.

[0031] With the method described above, it is possible to produce the base plate having a plate thickness between 10 nm and 5 μm, on which structural elements having an elevated length of 50 nm to 5 μm.

[0032] In a preferred configuration of the base plate 3 inside the carrier substrate, which is made of the individual polyimide layers Pl, the base plate 3 is situated centrally within the carrier substrate. The goal is to form the first polyimide layer at step a) so that the thickness is enough to corresponds to the total thickness of the additional polyimide layers Pl, which are applied at steps i) and u). This configuration of the base plate 3 has the experimentally verifiable advantage which is that compensation is provided for inherent stresses which develop during a subsequent tempering process acting on the base plate. The tempering process is required to provide a material prestress into the carrier substrate, as a result of which the implantable cuff is capable of winding itself automatically around the nerve fiber bundle.

REFERENCE LIST

[0033] 1 carrier substrate [0034] 1′ carrier substrate surface [0035] 2 electrode [0036] 3 base plate [0037] 31 top side [0038] 32 bottom side [0039] 4 structural element [0040] 41 first surface area [0041] 42 web-type protrusion [0042] 43 second surface area [0043] 44 third surface area [0044] 5 adhesion promotion layer [0045] 5′ adhesion promotion layer configuration [0046] KO constellation [0047] LA longitudinal extent