ELECTRODE ARRAY AND METHOD OF FABRICATION

• US 20110180305A1
• Filed: 01/22/2010
• Published: 07/28/2011
• Est. Priority Date: 01/22/2010
• Status: Active Grant

• Current Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Original Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Inventors: Johnson, Angelique, Wise, Kensall
• Granted Patent: US 8,283,569 B2
• Time in Patent Office: Days
• US Class Current: 174/250
• CPC Class Codes: A61N 1/0541 Cochlear electrodes
• CPC Class Codes: Y10T 29/49155 Manufacturing circuit on or in base
• CPC Class Codes: Y10T 428/31681 Next to polyester, polyamide or polyimide [e.g., alkyd, glue, or nylon, etc.]

Abstract

An electrode array, having application as a cochlear implant, includes a tube formed of Parylene defining a hollow channel. A substrate formed primarily of Parylene is supported by the tube. In turn, a plurality of metallic electrodes and feed lines are supported by the substrate. Numerous voids are defined by the tube which opens into the hollow channel. The size and spacing of the voids regulate stiffness and curl of the tube to provide excellent fit within the cochlea.

Claims

1. A method of fabricating an electrode array, said method comprising the steps of:

depositing a first composition on a carrier wafer wherein the first composition defines a longitudinal slit and the first composition forms a first layer of a substrate;

etching the carrier wafer through the longitudinal slit to define a channel underneath the first layer;

depositing a second composition comprising a polymer through the longitudinal slit and onto the carrier wafer to form a tube around the channel and seal the longitudinal slit;

disposing a plurality of feed lines comprised of conductive material on the substrate opposite the tube;

disposing a plurality of electrodes on the substrate with each electrode electrically connected to at least one of the feed lines;

etching the carrier wafer opposite the substrate to define voids with each void exposing an area of the tube;

removing the areas of the tube exposed by the voids to define slots within the tube; and

releasing the tube and substrate from the carrier wafer.

2. A method as set forth in claim 1 further comprising the step of depositing a third composition comprised of a polymer on the substrate to form another layer of the substrate wherein the third composition defines a plurality of openings with each opening proximate to one of the electrodes to expose the electrodes and allow electrical conduction with the electrodes.

3. A method as set forth in claim 1 wherein the substrate defines a peripheral edge and further comprising the step of disposing a curl strip adjacent the peripheral edge of the substrate.

4. A method as set forth in claim 1 wherein a maximum depth of the channel is about 150-200 μ

m below the level of the substrate.

5. A method as set forth in claim 1 wherein said step of releasing the tube and substrate from the carrier wafer is further defined as dissolving the carrier wafer using a solution including potassium hydroxide.

6. A method as set forth in claim 1 wherein said step of depositing the first composition on the carrier wafer is further defined as the steps of:

depositing the first composition comprised of Parylene on the carrier wafer; and

etching a longitudinal slit using directional O₂ plasma reactive-ion etching.

7. A method as set forth in claim 1 wherein said step of depositing the second composition is further defined as depositing the second composition comprising Parylene using vapor deposition through the longitudinal slit and onto the carrier wafer to form a tube around the channel and seal the longitudinal slit and onto the first layer to form a second layer.

8. An electrode array comprising:

a tube having at least one wall defining a channel;

a substrate comprised of non-conductive material and supported at least partially by the tube;

a plurality of electrodes comprised of a conductive material and supported by the substrate; and

a plurality of feed lines comprised of a conductive material and disposed primarily within the substrate wherein each feed line is electrically connected to at least one of the plurality of electrodes;

wherein the at least one wall of the tube defines a plurality of slots into the hollow channel for regulating stiffness and curl of the tube.

9. An electrode array as set forth in claim 8 wherein the tube comprises Parylene.

10. An electrode array as set forth in claim 8 wherein the tube comprises a metal.

11. An electrode array as set forth in claim 8 wherein the substrate defines a peripheral edge and the electrode array further comprises a curl strip disposed adjacent at least a portion of the peripheral edge.

12. An electrode array as set forth in claim 11 wherein the curl strip is bimetallic.

13. An electrode array as set forth in claim 8 wherein the electrodes comprise metal.

14. An electrode array as set forth in claim 8 wherein the substrate includes a first layer of a polymer supported at least partially by the tube and at least one insulating layer of a polymer disposed on the base layer opposite the tube.

15. An electrode array as set forth in claim 14 wherein said at least one insulating layer comprises a second layer disposed on the first layer opposite the tube and a third layer disposed on the second layer opposite the tube.

16. An electrode array as set forth in claim 15 wherein the feed lines are disposed between the first layer and the second layer.

17. An electrode array as set forth in claim 16 wherein the electrodes are disposed between the second layer and the third layer.

18. An electrode array as set forth in claim 8 wherein each of said electrodes has a generally circular shape and a diameter less than 200 μ

m and a pitch between electrodes of less than 300 μ

m.

19. An electrode array comprising:

a tube comprised of Parylene and having at least one wall defining a channel;

a substrate comprised of non-conductive material and supported at least partially by the tube;

a plurality of electrodes comprised of a conductive material and supported by the substrate; and

a plurality of feed lines comprised of a conductive material and disposed primarily within the substrate wherein each feed line is electrically connected to at least one of the plurality of electrodes.

20. An electrode array as set forth in claim 19 wherein a pitch between electrodes is less than 300 μ

m.