Microelectrode systems for neuro-stimulation and neuro-sensing and microchip packaging and related methods

• US 20070123766A1
• Filed: 09/29/2006
• Published: 05/31/2007
• Est. Priority Date: 09/29/2005
• Status: Active Grant

• Current Assignee: Doheny Eye Institute
• Original Assignee: Doheny Eye Institute
• Inventors: Humayun, Mark, Weiland, James, Whalen, John
• Granted Patent: US 8,195,266 B2
• Time in Patent Office: Days
• US Class Current: 600/395
• CPC Class Codes: A61B 2562/0215 Silver or silver chloride containing
• CPC Class Codes: A61B 2562/0217 Electrolyte containing
• CPC Class Codes: A61B 2562/125 characterised by the manufacture of electrodes
• CPC Class Codes: A61B 5/24 Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
• CPC Class Codes: A61B 5/685 Microneedles
• CPC Class Codes: A61N 1/04 Electrodes electrosurgical electrodes A61B18/14
• CPC Class Codes: A61N 1/0541 Cochlear electrodes
• CPC Class Codes: A61N 1/0543 Retinal electrodes
• CPC Class Codes: A61N 1/0551 Spinal or peripheral nerve electrodes
• CPC Class Codes: A61N 1/37205 Microstimulators, e.g. implantable through a cannula
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 15/00 Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites

Abstract

Microelectrode assemblies and related methods are disclosed for bio-stimulating and/or bio-sensing a target tissue. The assemblies can include a two-side substrate, an array of microelectrodes, each of the microelectrodes including a nano-wire embedded within the substrate and extending from a proximal end to a distal end and through the substrate, each nano-wire having a diameter preferably less than 1 μm. The substrate can include portions made of nano-porous material(s) through which the microelectrodes pass. The substrate with the embedded nano-wires can effectively be fluid impermeable. The proximal ends of the nano-wires can be adapted to be connected to an electronic device and the distal ends are adapted to be disposed in a biological environment for bio-stimulating a target tissue and/or bio-sensing activities of the target tissue. Suitable alloys such as platinum, platinum-iridium, and/or other noble-metal-alloyed compositions can be used for the nano-wires.

Claims

1. A microelectrode assembly for bio-stimulating and/or bio-sensing a target tissue comprising:

a substrate having a first side and a second side; and

an array of microelectrodes, each of the microelectrodes including a nano-wire embedded within the substrate and extending from a proximal end at the first side to a distal end at the second side, each nano-wire having a diameter less than 1 μ

m,

wherein the substrate with the embedded nano-wires is fluid impermeable, and wherein the proximal ends are adapted to be connected to an electronic device and the distal ends are adapted to be disposed in a biological environment,

and wherein the nano-wires are made from an alloy of about 88% platinum and about 12% iridium by molar fraction.

2. A microelectrode assembly according to claim 1, wherein the substrate is made from a biocompatible material.

3. A microelectrode assembly according to claim 1, wherein the substrate is made from a ceramic material.

4. A microelectrode assembly according to claim 1, wherein the substrate is made from aluminum oxide.

5. A microelectrode assembly according to claim 1, wherein the substrate is made from a polymer.

6. A microelectrode assembly according to claim 1, wherein the alloy further includes platinum oxide and iridium oxide.

7. A microelectrode assembly according to claim 1, wherein the nano-wire has a diameter equal to or less than 200 nm.

8. A microelectrode assembly according to claim 1, wherein the substrate has a thickness equal to or greater than 50 μ

m.

9. A microelectrode assembly according to claim 1, wherein the array of microelectrodes are distributed in the substrate with a pattern.

10. A microelectrode assembly according to claim 1, wherein the substrate has a curvature that conforms to a curvature of the target tissue.

11. A microelectrode assembly according to claim 1, wherein the nano-wires extend out of the substrate at least one of the first side and the second side of the substrate.

12. A microelectrode system includes multiple microelectrode assemblies of claim 1.

13. A method of making a microelectrode assembly having an array of microelectrodes for bio-stimulating and/or bio-sensing a target tissue comprising:

providing a substrate having a first side and a second side and an array of nano-channels passing through the substrate from the first side to the second side, each of the nano-channels having a diameter less than 1 μ

m;

depositing a layer of electrically conductive material on the first side; and

electrodepositing an electrically conductive material into the array of nano-channels to fill the nano-channels from the second side to form the array of microelectrodes, wherein the electrically conductive material includes an alloy of about 88% platinum and about 12% iridium by molar fraction.

14. A method according to claim 13, wherein, before depositing a layer of electrically conductive material on the first side, the method further comprises:

depositing a layer of photoresist on the first side; and

patterning the layer of photoresist to define a pattern for the array of microelectrodes.

15. A method according to claim 13, wherein the substrate is made from a ceramic material.

16. A method according to claim 13, wherein the substrate is made from aluminum oxide.

17. A method according to claim 13, wherein the alloy further includes platinum oxide and iridium oxide.

18. A method according to claim 17, wherein electrodepositing an electrically conductive material into the array of nano-channels to fill the nano-channels from the second side to form the array of microelectrodes includes immersing the array of nano-channels in a deposition solution.

19. A method according to claim 13 further comprising at least partially removing the layer of the electrically conductive material.

20. A method according to claim 19 further comprising partially removing the substrate from the first side of the substrate to partially reveal the microelectrodes.

21. A method according to claim 13 further comprising partially removing the substrate from the second side of the substrate to partially reveal the microelectrodes.

22. A method according to claim 18, wherein the solution includes ammonium hexachloroplatinate and sodium hexachloroiridate.

23. A method according to claim 13 further comprising forming the substrate with the microelectrodes to form a curvature at least one of the first side and the second side, and wherein the curvature conforms to a curvature of the target tissue.

24. A method according to claim 13, wherein the substrate includes a barrier layer at the first side, and wherein the method further comprising patterning the barrier layer to define a pattern for the array of microelectrodes.

57. The method of claim 13, further comprising sintering the substrate.

25. A method of making a microelectrode assembly having an array of microelectrodes for bio-stimulating and/or bio-sensing a target tissue comprising:

providing a substrate having a first side and a second side and an array of nano-channels passing through the substrate from the first side to the second side, each of the nano-channels having a diameter less than 1 μ

m;

providing an electrolyte including ammonium hexachloroplatinate and sodium hexachloroiridate; and

using the electrolyte to electrodeposit platinum and iridium into the array of nano-channels to fill the nano-channels to form the array of microelectrodes, wherein the microelectrodes include an alloy of platinum and iridium.

26. A method according to claim 25, wherein providing an electrolyte including ammonium hexachloroplatinate and sodium hexachloroiridate includes mixing a first electrolyte including ammonium hexachloroplatinate and a second electrolyte including sodium hexachloroiridate.

27. A method according to claim 26, wherein mixing a first electrolyte including ammonium hexachloroplatinate and a second electrolyte including sodium hexachloroiridate includes forming the first electrolyte by mixing ammonium hexachloroplatinate and sodium hydrogen phosphate in water.

28. A method according to claim 26, wherein mixing a first electrolyte including ammonium hexachloroplatinate and a second electrolyte including sodium hexachloroiridate includes forming the second electrolyte by adding sodium hexachloroiridate in HCl solution.

29. A method according to claim 25, wherein the method further comprises:

depositing a layer of photoresist on the first side; and

patterning the layer of photoresist to define a pattern for the array of microelectrodes.

30. A method according to claim 25, wherein the substrate is made from a ceramic material.

31. A method according to claim 25, wherein the substrate is made from aluminum oxide.

32. A method according to claim 25 further comprising partially removing the substrate from the first side of the substrate to partially reveal the microelectrodes.

33. A method according to claim 25 further comprising partially removing the substrate from the second side of the substrate to partially reveal the microelectrodes.

34. A method according to claim 25, wherein the substrate has a curvature at least one of the first side and the second side that conforms to a curvature of the target tissue.

35. A method according to claim 25, further comprising machining the substrate with the microelectrodes to form a curvature at least one of the first side and the second side, and wherein the curvature conforms to a curvature of the target tissue.

36. A method according to claim 25, wherein the substrate includes a barrier layer at the first side, and wherein the method further comprising patterning the barrier layer to define a pattern for the array of microelectrodes.

56. The method of claim 25, wherein using the electrolyte to electrodeposit platinum and iridium into the array of nano-channels includes non-steady-state application of potential.

37. A microelectrode assembly for bio-stimulating and/or bio-sensing a target tissue comprising:

a substrate having a first side and a second side; and

an array of microelectrodes, each of the microelectrodes including a nano-wire embedded within the substrate and extending from a proximal end at the first side to a distal end at the second side, each nano-wire having a diameter less than 1 μ

m,

wherein each of the nano-wires includes a first section of a first electrically conductive material and a second section of a second electrically conductive material, which is different from the first electrically conductive material.

38. A microelectrode assembly according to claim 37, wherein the first electrically conductive material is gold.

39. A microelectrode assembly according to claim 37, wherein the second electrically conductive material is selected from a group consisting of platinum, platinum oxide, iridium, iridium oxide, platinum-iridium alloy, tantalum, tantalum oxide, carbon, and ruthenium.

40. A microelectrode assembly according to claim 37, wherein the substrate with the embedded nano-wires is fluid impermeable.

41. A microelectrode system includes multiple microelectrode assemblies of claim 37.

42. A method of making a microelectrode assembly having an array of microelectrodes for bio-stimulating and/or bio-sensing a target tissue comprising:

providing a substrate having a first side and a second side and an array of nano-channels passing through the substrate from the first side to the second side, each of the nano-channels having a diameter less than 1 μ

m;

electrodepositing a first electrically conductive material into the array of nano-channels to partially fill the nano-channels; and

electrodepositing a second electrically conductive material, which is different from the first electrically conductive material, into the array of nano-channels to fill the nano-channels.

43. A method according to claim 42, wherein the first electrically conductive material is gold.

44. A method according to claim 43, wherein the second electrically conductive material is selected from a group consisting of platinum, platinum oxide, iridium, iridium oxide, platinum-iridium alloy, tantalum, tantalum oxide, carbon, and ruthenium.

45. A microelectrode assembly for bio-stimulating and/or bio-sensing a target tissue comprising:

a substrate having a first side and a second side, wherein the substrate includes a plurality of nano-porous portions, each extending through the substrate from the first side to the second side; and

an array of microelectrodes, each microelectrode including a nano-wire embedded within a nano-porous portion of the substrate and extending from a proximal end at the first side to a distal end at the second side, each nano-wire having a diameter less than 1 μ

m,

wherein the substrate with the embedded nano-wires is fluid impermeable, and wherein the proximal ends are adapted to be connected to an electronic device and the distal ends are adapted to be disposed in a biological environment.

46. The assembly of claim 45, wherein the nano-wires include an alloy of about 88% platinum and about 12% iridium by molar fraction.

47. The assembly of claim 46, wherein the nano-wires include platinum.

48. The assembly of claim 47, wherein the nano-wires include a noble-metal-alloy.

49. The assembly of claim 47, wherein the substrate includes aluminum oxide.

50. The assembly of claim 47, wherein the nano-porous portions include aluminum oxide.

51. The assembly of claim 47, wherein the nano-porous portions include calcium-phosphate.

52. The assembly of claim 51, wherein the calcium-phosphate includes tri-calcium phosphate.

53. The assembly of claim 47, wherein the substrate includes calcium-phosphate.

54. The assembly of claim 47, wherein the nano-porous sections include hydroxyappatite.

55. The assembly of claim 47, wherein the nano-porous sections include nano-diamond.