Methods for Forming an Electrode Device with Reduced Impedance

• US 20130066182A1
• Filed: 09/14/2012
• Published: 03/14/2013
• Est. Priority Date: 09/14/2011
• Status: Active Grant

• Current Assignee: Neuronexus Technologies Incorporated (NEL Group, Inc.)
• Original Assignee: Neuronexus Technologies Incorporated (NEL Group, Inc.)
• Inventors: Seymour, John P.
• Granted Patent: US 9,192,757 B2
• Time in Patent Office: Days
• US Class Current: 600/377
• CPC Class Codes: A61B 2562/0285 Nanoscale sensors
• 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 5/68 Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
• CPC Class Codes: A61N 1/04 Electrodes electrosurgical electrodes A61B18/14
• CPC Class Codes: A61N 1/05 for implantation or insertion into the body, e.g. heart electrode A61N1/06 takes precedence
• CPC Class Codes: A61N 1/0534 Electrodes for deep brain stimulation

Abstract

Improved low-cost, highly reliable methods for increasing the electrochemical surface area of neural electrodes are described. A mono-layer of polymeric nanospheres is first deposited on a metallization supported on a dielectric substrate. The nanospheres self-assemble into generally repeating lattice forms with interstitial space between them. Then, the geometric surface area of the metallization material is increased by either selectively etching part-way into its depth at the interstitial space between adjacent nanospheres. Another technique is to deposit addition metallization material into the interstitial space. The result is undulation surface features provided on the exposed surface of the metallization. This helps improve the electrochemical surface area when the treated metallizations are fabricated into electrodes.

Claims

1. A neural interface system, which comprises:

a) a substrate;

b) at least one primary metallization supported on the substrate, wherein. the primary metallization. has a perimeter extending from a lower metallization surface supported on the substrate to an upper metallization surface spaced from the lower metal1ization surface by a thickness of the perimeter, wherein the upper surface of the primary metallization. is characterized by a plurality of undulating structures, and

c) wherein the substrate supporting the primary metallization with the undulating structures on its upper metallization surface thereof is provided in a shape that is suitable for contact with body tissue.

2. The neural interface system of claim 1 wherein the substrate is of a. dielectric material selected from the group consisting of parylene, polyimide, silicone, silicon carbide, and silicon.

3. The neural interface system of claim 1 wherein the primary metallization is of a material. selected from the groups consisting of gold, platinum, platinum/iridium alloy, iridium oxide, and titanium. nitride.

4. The neural interface system of claim 1 wherein the thickness of the primary metallization ranges from about 10 micron to about 20 microns.

5. The neural interface system of claim 1 wherein the undulating structures comprise a plurality of recesses that extending part way into the thickness of the primary metallization.

6. The neural interface system of claim 1 wherein the recesses extend from about 50% to about 90% into the thickness of the primary metallization from the upper surface thereof.

7. The neural interface system of claim 1 wherein the recesses are not in communication with each other.

8. The neural interface system of claim 1 wherein the undulating structures comprise a plurality of upstanding secondary metallizations supported on the upper surface of the primary metallization.

9. The neural interface system of claim 8 wherein a second thickness of the upstanding secondary metallizations ranges from about 225 nm to about 2,250 nm above the upper surface of the primary metallization.

10. The neural interface system of claim 1 wherein the primary metallization and the second metallization are of the same or different materials.

11. A method for providing a neural interface system, comprising the steps of

a) providing a substrate;

b) depositing at least one primary metallization supported on the substrate, the primary metallization comprising a perimeter extending from a lower metallization surface supported on the substrate to an upper metallization surface spaced from the lower metallization surface by a thickness of the perimeter;

c) depositing a monolayer of nanospheres contacting the upper surface of the metallization, and

d) treating the upper surface of the primary metallization not contacted by the nanospheres to thereby provide a plurality of undulating structures.

12. The method of claim 11 including providing the thickness of the primary metallization ranging from about 10 micron to about 20 microns.

13. The method of claim 11 including providing the nanospheres are comprised of polystyrene or glass.

14. The method of claim 11 including mixing the nanospheres with ethanol and de-ionized water to form a nanosphere solution that is deposited on the primary metallizations.

15. The method of claim 11 including providing the undulating structures by etching recesses part-way through the thickness of the metallization from the upper surface thereof.

16. The method of claim 15 including providing the nanospheres having a diameter ranging from about 20 nm to about 1,000 nm.

17. The method of claim. 15 including providing the recesses extending from about 50% to about 90% into the thickness of the primary metallization from the upper surface thereof and not being in communication with each other.

18. The method of claim 11 including depositing a second metallization on the primary metallization to thereby provide the undulating structures.

19. The method of claim 18 including providing the nanospheres having a diameter ranging from about 500 nm to about 5,000 nm.

20. The method of claim 18 including providing a second thickness of the upstanding secondary metallizations ranging from about 225 nm to about 2,250 nm above the upper surface of the primary metallization.

21. The method of claim 18 including discontinuing deposition of the secondary metallization when its thickness has reached about 90% of a radius of the nanospheres.

22. The method of claim 11 including:

i) depositing a relatively more etchable second metallization material on the primary metallization followed depositing a relatively less etchable tertiary metallization material on the second metallization material to thereby form a metallization stack; and

ii) etching the metallization stack to remove a portion of the second metallization so that a greater surface area of the primary and tertiary metallization materials is obtained.

23. The method of claim 22 including the primary and tertiary metallization materials being the same of different.

24. The method of claim 22 including providing the secondary metallization material being gold.

25. The method of claim 22 including selecting the primary and tertiary metallization materials from the group consisting of platinum, iridium, iridium oxide, and titanium nitride