Implantable Electrical Contact Arrangement

Abstract

An implantable electrical contact arrangement comprising at least one electrode element entirely integrated into a carrier substrate of a biocompatible, electrically insulating material, and at least one freely accessible electrode surface enclosed by the biocompatible, electrically insulating carrier substrate. Within a sub-space which does not contain an electrode element, the carrier substrate surrounds at least one space containing at least one material with a modulus of elasticity differing from a modulus of elasticity of the material of the carrier substrate.

Claims

1-17: (canceled)

18. An implantable electrical contact comprising: at least one electrode integrated into a carrier substrate of a biocompatible electrically insulating material and at least one accessible electrode surface enclosed by the biocompatible electrically insulating carrier substrate; a sub-space not containing the at least one electrode; and the carrier substrate of a biocompatible electrically insulating material surrounding at least one space containing at least one material having a modulus of elasticity differing from a modulus of elasticity of the material of the carrier substrate of a biocompatible electrically insulating material.

19. An implantable electrical contact arrangement according to claim 18, wherein the carrier substrate with the at least one electrode is a neutral fiber separating the sub-space containing the at least one electrode containing the at least one space.

20. An implantable electrical contact arrangement according to claim 18, comprising an orthogonal projection onto the electrode surface and the at least one space overlapping, at least partially, the electrode surface.

21. An implantable electrical contact arrangement according to claim 18, wherein the carrier substrate of a biocompatible electrically insulating material is a polymer of one of: polyimide, liquid crystal polymer (LCP), parylene or PDMS.

22. An implantable electrical contact according to claim 18, wherein: the carrier substrate of a biocompatible electrically insulating material is a sheet with a carrier substrate side having the at least one accessible electrode surface and opposite thereto a carrier substrate underside having at least one space extending in parallel to the carrier substrate of a biocompatible electrically insulating material upper side and to the carrier substrate underside of a biocompatible electrically insulating material which contains the at least one material having a modulus of elasticity differing from a modulus of elasticity of a biocompatible electrically insulating material of the material of the carrier substrate.

23. An implantable electrical contact according to claim 18, wherein: the biocompatible electrically insulating material is gaseous, liquid or a solid.

24. An implantable electrical contact according to claim 18, comprising: at least two materials each with a different modulus of elasticity are contained within the at least one space.

25. An implantable electrical contact according to claim 18, wherein: the at least one material is a transducer material.

26. An implantable electrical contact according to claim 25, wherein: the transducer material is a material chosen from the group of materials of: bimetal, shape-memory alloy, piezo ceramic, electrostrictive ceramic, magnetoscriptive alloy, electro- or magnetorheological fluid.

27. An implantable electrical contact according to claim 22, wherein: the sheet carrier substrate of a biocompatible electrically insulating material has a longitudinal direction, the space is dimensioned to be smaller in a longitudinal direction of the sheet.

28. An implantable electrical contact according to claim 18, wherein: the at least one space encloses a spatial volume of a maximum of 17 mm.sup.3.

29. An implantable electrical contact according to claim 27, wherein: a dimension orientated in the longitudinal direction of the sheet is at least one order of magnitude smaller.

30. An implantable electrical contact according to claim 18, wherein: the at least one space and the material contained in the at least one space does not to exert a force which determines a spatial shape of the implantable electrically contact.

31. An implantable electrical contact according to claim 18, comprising: first spaces filled with at least one material, which is in an array along a first straight line or along a first plane with each being spaced apart from each other within the carrier substrate.

32. An implantable electrical contact according to claim 31, comprising: second spaces each filled with at least one material which is in a second straight line or along a second plane and are separated from each other within the carrier substrate.

33. An implantable electrical contact arrangement according to claim 33, wherein: the first and the second straight lines or the first and the second planes are orientated parallel to each other.

34. An implantable electrical contact arrangement according to claim 32, comprising: additional spaces each filled with at least one material distributed along an additional straight line or along an additional plane which separated within the carrier substrate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The invention will be described below without restricting the general inventive concept by way of examples of embodiment with reference to the drawings. Here:

[0030] FIGS. 1 a, b, c each show a longitudinal section through a carrier substrate with an electrode arrangement and at least one space.

DETAILED DESCRIPTION OF THE INVENTION

[0031] FIG. 1a shows a longitudinal section through a sheet of carrier substrate 1, preferably in the form of polyimide film, with a carrier substrate upper side 2, and opposite this, a carrier substrate underside 3. Embedded within the carrier substrate 1 is an electrode arrangement which comprises at least one electrode element 4 which is contacted via electrical supply and outlet leads 5 extending within the carrier substrate 1. The electrode element 4 comprises a freely accessible electrode surface 6. Not necessarily, but advantageously, the electrode element 4 projects beyond the carrier substrate upper side 2, which in the implanted state is orientated towards an intracorporeal tissue surface, which is not shown, so that the electrode surface 6 comes into surface contact with the tissue surface.

[0032] The sheet of the carrier substrate 1 comprises a neutral fiber 7, which separates the carrier substrate 1 into an upper sub-space 8 and a lower sub-space 9. The upper sub-space 8 contains the electrode arrangement, whereas the lower sub-space of the carrier substrate 1 contains at least one space 10, which is completely enclosed by the material of the carrier substrate 1 and in which at least one material 11 is contained which has a modulus of elasticity E1 which differs from the modulus of elasticity E.sub.t of the carrier substrate 1.

[0033] In the example embodiment shown in FIG. 1a, there is an orthogonal projection onto the carrier substrate upper side 2 and the space 10 is locally arranged to completely overlap underneath the electrode element 4.

[0034] A preferred material selection is the use of a metallic substance 11 within the space 10, which is preferably in the form of a one-piece metallic layer, that is completely surrounded by the biocompatible, electrically insulating material of the carrier substrate 1 in an all-encompassing manner. The metallic substance 11 can locally stiffen the carrier substrate 1, so that when the carrier substrate is designed as a cuff electrode, a local increase in the contact pressure is achieved in the region of the electrode element 4 on an intracorporeal tissue surface, which is preferably a nerve fiber bundle. The additional implanting or integration of a material 11 within the space 10 is not associated with an increase in the carrier substrate thickness d.

[0035] The spatial and dimensional arrangement, of the space 10 within the carrier substrate can be diversely selected.

[0036] FIG. 1b illustrates an alternative embodiment that has individual spaces 10′ within the carrier substrate 1 which are all uniformly filled with one material 11 or each are filled with different materials, depending on the desired setting of the stiffness of the carrier substrate 1 in the region of the at least one electrode element 4. In FIG. 1b, the spaces 10′ are arranged along a plane e1 running in parallel to the neutral fiber 7. Also alternative arrangement patterns of the individual spaces 10′ may be used, for example within two or more planes e1, e2 etc. running parallel to each other.

[0037] FIG. 1c illustrates a further example of embodiment with at least two spaces 10″, which each orthogonally project onto the carrier substrate upper side 2 and are applied laterally next to the electrode 4. In this case, when the spaces 10′ are filled with a material having a higher modulus of elasticity than the modulus of elasticity of the carrier substrate 1, the carrier substrate 1 has a lower stiffness in the region of the electrode arrangement than in regions of the carrier substrate which laterally are adjoining it.

[0038] Common to all embodiments is the fact that as a result of the provision within the carrier substrate 1 of a space, or spaces, which are each filled with at least one material, without an increase in the thickness of the sheet carrier substrate, that produces randomly stiffness gradients can be defined within the carrier substrate 1. Not at least because of the free selection of materials for filling the individual spaces, which in addition to solids can also include gaseous or, in particular, liquid or gel-like substances, the surface stiffness behavior of the entire carrier substrate can be finished to have an individual and finely-controlled manner.

[0039] Also possible is the use of fabric or fiber materials, which can be integrated in a locally limited way within the carrier substrate individually or in layers. For example, in the case of a fabric layer, this can be surrounded like a matrix by the biocompatible, electrically non-conductive material of the carrier substrate.

[0040] According to the invention at least one space within the carrier substrate is filled with a material having the modulus of elasticity of which differing from the modulus of elasticity of the carrier substrate, which also serves to compensate for mechanical stresses that occur within the carrier substrate as a result of the integration of the electrode arrangement inside the carrier substrate. Such mechanical stresses can lead to excessive material stresses within the carrier substrate and ultimately restrict the lifespan of the implantable electrical contact arrangement. More particularly, designing the implantable electrical contact arrangement in the form of a known cuff electrode results in material-intrinsic mechanical stresses, which can be completely, or at least largely compensated by way of at least one material-filled space within the carrier substrate.

LIST OF REFERENCE NUMBERS

[0041] 1 Carrier substrate [0042] 2 Upper side of carrier substrate [0043] 3 Lower side of carrier substrate [0044] 4 Electrode element [0045] 5 Electrical supply and outlet lead [0046] 6 Electrode surface [0047] 7 Neutral fiber [0048] 8 Sub-space containing the electrode element arrangement [0049] 9 Sub-space containing the at least one space [0050] 10, 10′, 10″ Space [0051] 11 Material [0052] e1, e2 Arrangement plane for the spaces [0053] d Sheet thickness of the carrier substrate [0054] E1 Modulus of elasticity of the material [0055] E.sub.T Modulus of elasticity of the carrier substrate