High density array of micro-machined electrodes for neural stimulation
The present invention is a micro-machined electrode for neural-electronic interfaces which can achieve a ten times lower impedance and higher charge injection limit for a given material and planar area.
1. A single electrode with enhanced surface area comprising:
a single electrode base having a conductive surface with a planar surface area; and
a plurality of micromachined conductive protuberance on said surface of said single electrode base; wherein a physical surface area of said single electrode base results in a reduction in the electrode impedance at low frequencies relative to said planar surface area.
2. The electrode according to claim 1 , wherein said protuberances are posts.
3. The electrode according to claim 2 , wherein said posts are hollow posts.
4. The electrode according to claim 1 , wherein said protuberances are ridges.
5. The electrode according to claim 1 , wherein said protuberances comprise platinum.
6. The electrode according to claim 1 , wherein said protuberances comprise gold.
7. The electrode according to claim 1 , wherein said protuberances comprise gold covered with platinum.
8. The electrode according to claim 1 , wherein said protuberances comprise iridium.
9. The electrode according to claim 1 , wherein said protuberances comprise iridium oxide.
10. The electrode according to claim 1 , wherein said protuberances comprise titanium oxide.
11. The electrode according to claim 1 , wherein said protuberances comprise a first metal and a second metal forming a hermetic seal over said first metal.
12. An electrode array comprising:
a lower flexible insulating layer;
a flexible conductive layer;
an upper flexible insulating layer including voids exposing a portion of said flexible conductive layer having a conductive surface with a planar surface area; and
a plurality of micromachined conductive protuberance on said surface.
13. The electrode array according to claim 12 , wherein at least one of said flexible insulating layers comprises polyimide.
14. The electrode array according to claim 12 , wherein said flexible conductive layer comprises platinum.
15. The electrode array according to claim 12 , wherein said flexible conductive layer comprises titanium.
16. The electrode array according to claim 12 , wherein said protuberances comprise gold.
17. The electrode array according to claim 12 , wherein said protuberances are posts.
18. The electrode array according to claim 17 , wherein said post are hollow posts.
19. The electrode array according to claim 12 , wherein said protuberances are ridges.
20. A method of increasing an electrode effective surface area of a single electrode comprising the steps of:
providing a single conductive electrode base having a planar surface area; and
micromachining a plurality of conductive protuberances on the surface of said single electrode base; said plurality of protuberances comprising a first metal and a second metal covering said first metal; wherein said physical surface area of said single electrode results in a reduction in the electrode impedance at low frequencies relative to the single electrode base planar surface area.