Implantable Electrical Contact Array

Abstract

An implantable electrical contact array is described, which has at least one electrode element array completely surrounded by a biocompatible electrically insulating material and an electrode surface directly or indirectly surrounded by the biocompatible electrically insulating material, the electrode element array having a layer composite in a laminated shape with a metallization layer on at least a ceramic substrate on an adhesion-promoting layer. The invention is characterized in that the layer composite in a laminated shape is bonded to a passivation layer by forming covalent bonds and is completely encapsulated by the passivation layer except for at least one surface area of ​​the metallization layer facing away from the layer composite, the passivation layer has a surface facing away from the layer composite in a laminated shape and is directly or indirectly adjacent to the passivation layer, and the passivation layer is deposited on the layer composite in a laminated shape by plasma-enhanced chemical vapor deposition (PECVD), physical vapor deposition (PVD) or wet-chemical coating.

Description

[Technical Field]

[0001] An implantable electrical contact array is described having at least one electrode element array completely surrounded by a biocompatible, electrically insulating material, with at least one electrode surface surrounded directly or indirectly by the biocompatible, electrically insulating material, the electrode element array having a layer composite in a laminate configuration having a metallized layer on at least a ceramic substrate on an adhesion promoting layer. [Background technology]

[0002] A particular challenge in the manufacture and design of implantable electrical contact arrays in which electrical leads or lead structures electrically contact one another is the prevention of water or moisture penetration into and / or through the material interfaces contained within the electrical contact array. Water contact on conductive leads and electrode structures made primarily of metallic materials leads to irreversible signs of degradation and associated impairment of electrical energy and signal transmission characteristics. Furthermore, a permanently moist environment leads to signs of delamination between the metallic structures contained within the electrical contact array and the immediately surrounding surfaces, which are usually made of polymeric materials, ultimately reducing the useful life of such contact arrays.

[0003] According to a paper by Patrick Kiele et al. entitled "Thin-layer metallization stacks act on active implants," published in IEEE Transactions on Components, Packing and Manufacturing Technology, Vol. 10, No. 11, November 2020, better results in terms of adhesive strength were obtained in the manufacture of medical implants with electrical connection or contact structures fabricated by conventional metal deposition processes, such as sputtering on ceramic substrates, preferably Al2O3 substrates, followed by a screen printing process using a metal paste with subsequent high-temperature processing. In particular, good results were achieved in the manufacture of such electrical contact structures by metallizing with sputtered aluminum on a tungsten-titanium adhesive layer, which can increase adhesive strength on aluminum oxide substrates. A biocompatible, electrically insulating material is then poured around the contact structures thus created to protect them from the wet internal environment of the body.

[0004] Document DE10 2016 222 710 A1 discloses an implantable electrical contact arrangement comprising an array of electrode elements completely surrounded by an electrically insulating material, with at least one freely accessible electrode surface surrounded directly or indirectly by a biocompatible electrically insulating material. Summary of the Invention

[0005] It is an object of the present invention to further develop an implantable electrical contact arrangement having at least one electrode element arrangement completely surrounded by a biocompatible electrically insulating material, having at least one electrode surface surrounded directly or indirectly by the biocompatible electrically insulating material, the electrode element arrangement having a laminated layer composite having a metallized layer on a ceramic substrate on at least an adhesion promoting layer such that the resistance of the implantable electrical contact arrangement surrounded by the biocompatible electrically insulating material is significantly improved with respect to moisture or water from most environments within the body, thereby extending the life of the medical implant and the manufacturer-specified maximum in-body operating duration.

[0006] The solution to the problem forming the basis of the present invention is set out in claim 1. Features further explaining the subject matter of the invention are set out in the subject matter of the dependent claims as well as in the detailed description, particularly with reference to the drawings.

[0007] According to the features of claim 1, the implantable electrical contact arrangement according to the invention is characterized in that the layer composite in the form of a laminate of the electrode element device is bonded to the passivation layer in a covalent bond-forming manner and is completely surrounded by the passivation layer except for at least one surface area of ​​the metallization layer facing away from the layer composite, and furthermore the passivation layer has a passivation layer surface facing away from the layer composite in the form of a laminate and directly or indirectly adjacent to the biocompatible electrically insulating material, which also forms a covalent bond with the biocompatible electrically insulating material on the side of the layer composite.

[0008] As a result of covalent or chemical bonds formed between the surface of the laminate-shaped layer composite and the passivation layer, and preferably between the passivation layer and the biocompatible electrically insulating material, respectively, as a result of external electronic interactions between atoms and / or molecules, penetration of moisture or water is at least largely eliminated, at least in the area of ​​the contact arrangement surrounded by the biocompatible electrically insulating material. In this way, delamination of the interfaces between two adjacent material layers, for example, interfaces within the laminate-shaped layer composite, the interface between the passivation layer and the laminate-shaped composite, and the interface between the passivation layer and the surrounding enclosure of the biocompatible electrically insulating material, can be largely eliminated.

[0009] Similar to the deposition of the adhesion promoter layer on the ceramic substrate and the metallization layer on the adhesion promoter layer, plasma-enhanced chemical vapor deposition (PECVD) is also suitable for the deposition of the passivation layer on the stacked layer composite and, if applicable, on the available surface area of ​​the ceramic substrate. Alternatively, suitable methods are physical vapor deposition (PVD) or wet-chemical coating of the passivation layer on the stacked layer composite and, optionally, on adjacent surface areas of the ceramic substrate.

[0010] The passivation layer is provided completely circumferentially on the surface of the layer composite in laminate form, with the proviso that at least the surface of the metallization layer provided for electrical contact with the electrical conductor structure is preferably in the form of an electrical cable, one end of which is soldered, bonded or adhesively connected to the surface of the metallization layer intended for contact, thereby providing a permanent, strong electrical contact.

[0011] After creating corresponding electrical contacts on the freely accessible surface areas of the metallization layer for this purpose, the layer composite in laminate form, together with the ceramic substrate, which is not completely covered with the passivation layer, is surrounded by a biocompatible electrically insulating material, preferably made of a polymer, thus seamlessly enclosing the layer composite in laminate form as part of the injection method and which can then be converted into a solid state by curing. Particularly preferred are the following types of polymers: silicone, polyimide resin, liquid crystal polymer (LCP) or parylene.

[0012] The encapsulation formed by the solidification of the cured biocompatible electrically insulating material also encloses the conductive structures in contact with the laminated layer composite.

[0013] The conductor structure connected in an electrically conductive manner to at least one surface region of the metallization layer can in principle have any function and form, and can, for example, be a separate electrical component connected to the metallization layer by at least one electrical connection, which, except for that electrical connection, is also covered by a passivation layer.

[0014] The layer composite in laminate form is preferably produced according to the design described in the publication cited in the introduction to Kiele et al., i.e. a titanium or tungsten-titanium layer is applied as an adhesion promoter layer onto an aluminum oxide layer as ceramic substrate, on top of which a platinum or gold layer is applied in the form of a metallization layer.

[0015] In principle, one of the following material compounds is suitable for the passivation layer: silicon oxide, silicon carbide, silicon nitride or silicon oxynitride. [Brief explanation of the drawings]

[0016] The invention will now be described by way of example, without limiting the general inventive concept, by way of example of embodiments, with reference to the drawings, in which: [Figure 1] FIG. 1 shows a perspective view from above of an implantable electrical contact array; [Figure 2] 1 shows a longitudinal section through an implantable contact arrangement in the area of ​​contact with an electrical conductor structure. DETAILED DESCRIPTION OF THE INVENTION

[0017] 1 shows a schematic perspective view of an implantable electrical contact structure designed in accordance with the present invention for electrical connection between an electrical lead 1 connected to an active medical implant (not shown) and a discharge lead 2 connected to an implantable power supply unit (not shown). The power supply unit provides electrical energy and control signals for operation of the medical implant.

[0018] For the purpose of 1:1 contact between the electrical leads 1 and the power supply and discharge leads 2, there are in each case two, preferably identically constructed, electrical contact arrangements 3, the layered structure of which is shown in a representative schematic manner in the cross-sectional view of FIG. 2.

[0019] On the other hand, the electrical contact 11 is for making electrical contact with the electrical lead 1, and the electrical contact 12 is for making electrical contact with the electrical supply and discharge lead 2. Each of the individual electrical contacts 11 and 12 is paired with a metallization layer designed in the form of a strip conductor 13 and electrically connected to each other.

[0020] By means of physical vapor deposition (PVD), a ceramic substrate 4 is deposited, preferably AlO 3, An adhesion promoting layer 5 consisting of, preferably a mud consisting of WTi or Ti is deposited on its surface, also using a PVD coating method, to deposit a metallization layer 6, preferably in the form of platinum or gold.

[0021] The deposition process for forming the metallization layer 6 is carried out using a suitable structure mask, which allows such a minimally sized and geometrically limited layer deposition onto the Al2O3 substrate 4 to be carried out.

[0022] Thereafter, by means of PVD deposition, a passivation layer 7 is applied both to the surface of the metallization layer 6 and to the surrounding surface area of ​​the ceramic substrate 4. Suitable as passivation layer 7 is preferably silicon oxide, which is able to form covalent bonds with both the metallization layer 6 and the ceramic layer 4. With regard to the passivation layer 7, only the surface area of ​​the metallization layer 6 remains uncovered, on which electrical contact with the power supply and discharge leads 2 or electrical leads 1, respectively, is subsequently envisaged.

[0023] 2, the surface area 8 of the metallization layer 6 intended for electrical contact of the power and discharge leads 2 is not covered by the passivation layer 7. The ends of the power and discharge leads 2 directly contact the surface area 8 of the metallization layer 6 intended for making contact and are firmly connected thereto electrically and mechanically by means of soldering, gluing or adhesive joints 9.

[0024] For preferably complete encapsulation or packaging of the implantable electrical contact array 3, a biocompatible electrically insulating material 10 is applied onto the surface of the passivation layer 7, preferably by means of an injection process, and forms a covalent bond therewith. Furthermore, the biocompatible conductive material 10 also surrounds the electrical contact areas 3 and, at least in the case of the electrical contacts 12, the electrical supply and discharge leads 2. The biocompatible conductive material 10 is electrically insulated from one another and is mechanically stable in the same way as the matrix immediately surrounding the electrical supply and discharge leads 2. The electrical connection between the electrical contacts 11 and 12 is achieved by a metallization layer 6, which is produced between the contacts in the form of separate strip conductors and which locally connects the contacts 11, 12 in pairs. Except for the surface area 8 of the metallization layer 6 intended for contacting the electrical cable 1 and the power and discharge leads 2 of the electrical contacts 11 and 12, a passivation layer 7 is deposited over the entire surface of the upper and lower surfaces of the ceramic substrate 4 and on the strip conductors 13, thereby forming a uniform surface for forming covalent bonds with a biocompatible and electrically insulating material layer 10 made of a polymer material applied thereon. [Explanation of symbols]

[0025] 1 Electrical Lead / Cable 2 power and discharge leads 3 Electrical contact arrangement 4. Ceramic substrate 5 Adhesion promotion layer 6 metallization layer 7 Passivation Layer 8. Surface area of ​​the metallized layer 9 Soldered, glued or adhesive connections 10 Biocompatible Electrical Insulating Materials 11 Electrical contacts 12 Electrical contacts 13 Strip conductor

Claims

1. An implantable electrical contact array (3) having at least one electrode element array completely surrounded by a biocompatible, electrically insulating material (10), and having at least one electrode surface directly or indirectly surrounded by said biocompatible, electrically insulating material (10), a layer composite in the form of a stack, comprising at least a metallized layer (6) on a ceramic substrate (4) above an adhesion-promoting layer (5), The stack-shaped layer composite is bonded to a passivation layer (7) so as to form covalent bonds and is completely surrounded by the passivation layer, except for at least one surface area (8) of the metallization layer (6) facing away from the layer composite, the passivation layer (7) has a passivation layer surface facing away from the stack-shaped layer composite and directly or indirectly adjacent to the electrically insulating material (10); said passivation layer (7) is deposited on said stack-shaped layer composite by plasma-enhanced chemical vapor deposition (PECVD), physical vapor deposition (PVD) or wet chemical coating; Contact arrangement.

2. 2. The contact arrangement according to claim 1, wherein the at least one surface area (8) of the metallization layer (6) not covered by the passivation layer (7) is equal to the at least one electrode surface area with which an electrical lead (1) or an electrical supply and discharge lead (2) contacts.

3. 3. A contact arrangement according to claim 1 or 2, wherein said metallization layer (6) is a layer of platinum or gold.

4. A contact arrangement according to any one of claims 1 to 3, wherein the adhesion promoter layer (5) is a tungsten-titanium or titanium layer.

5. A contact arrangement according to any one of claims 1 to 4, wherein the passivation layer (7) is a silicon oxide, silicon carbide, silicon nitride or silicon oxynitride layer.

6. The contact arrangement according to any one of claims 1 to 5, wherein the biocompatible, electrically insulating material (10) is a polymer.

7. The polymer is Silicone, polyimide, liquid crystal polymer (LCP), parylene, 7. The contact arrangement of claim 6, wherein the polymer is any one of the following:

8. 8. The contact arrangement according to any one of claims 1 to 7, wherein the biocompatible, electrically insulating material (10) is selected such that it is connected to at least the passivation layer (7) by covalent bonds.

9. 9. The contact arrangement according to claim 1, wherein an electrical component is connected to the metallization layer by means of at least one electrical connection, the metallization layer being covered with the passivation layer except for the electrical connection.

10. 10. The contact arrangement according to any one of the preceding claims, wherein the stack-shaped layer composite is bonded to the passivation layer (7) in an exclusively covalent manner.

11. 11. The contact arrangement according to any one of claims 1 to 10, wherein the passivation layer surface is bonded to the biocompatible, electrically insulating material (10) by exclusively covalent bonds.

12. 12. The contact arrangement according to any one of claims 2 to 11, wherein the electrical contact of the electrical leads (1) or the electrical supply and discharge leads (2) is implemented on the basis of solidified, bonded or glued connections (9).

13. The contact arrangement according to any one of the preceding claims, wherein the ceramic substrate (4) comprises an oxide ceramic.

14. The oxide ceramic is Al 2 O 3 or ZrO 2 14. The contact arrangement of claim 13, wherein:

Images