High Aspect Ratio Microelectrode Arrays Enabled to Have Customizable Lengths and Methods of Making the Same

• US 20120138335A1
• Filed: 06/03/2009
• Published: 06/07/2012
• Est. Priority Date: 06/03/2008
• Status: Active Grant

• Current Assignee: University of Utah Research Foundation (State of Utah)
• Original Assignee: University of Utah Research Foundation (State of Utah)
• Inventors: Solzbacher, Florian, Tathireddy, Prashant
• Granted Patent: US 8,886,279 B2
• Time in Patent Office: Days
• US Class Current: 174/250
• CPC Class Codes: A61N 1/0529 Electrodes for brain stimulation
• CPC Class Codes: A61N 1/0531 Brain cortex electrodes
• CPC Class Codes: Y10T 29/49117 Conductor or circuit manufacturing

Abstract

A method of fabricating an array of micro electrodes enabled to have customizable lengths. A substantially criss-cross pattern of channels on a top surface of the work-piece substrate (10) is formed using electrical discharge machining to form a plurality of shaped columns (20) having tapered profiles. The shaped columns have a tapering profile which extends at least 50% of the length of the columns. The plurality of shaped columns is etched to sharpen the tapered tips into needle tips forming the array of microelectrodes.

Claims

1. A method of fabricating an array of microelectrodes enabled to have customizable lengths, comprising:

providing a work-piece substrate;

forming a substantially criss-cross pattern of channels on a top surface of the work-piece substrate to form a plurality of shaped columns each having a tapered tip and a base, wherein the tapered tips have a tapering profile which extends at least 50% of a height of the shaped columns; and

etching the plurality of shaped columns to sharpen the tapered tips into needle tips to form the array of microelectrodes.

2. The method of claim 1, further comprising:

forming a second substantially criss-cross pattern of rectangular channels in the back surface of the work-piece substrate; and

filling the rectangular channels with a dielectric material prior to mounting the back surface of the work-piece substrate on the top surface of the support substrate.

3. The method of claim 2, wherein the forming the second pattern in the back surface is accomplished using a dicing saw prior to any EDM.

4. The method of claim 2, wherein the work-piece substrate comprises Si and the dielectric material comprises a glass.

5. The method of claim 2, wherein the work-piece substrate comprises metal and the dielectric material comprises an epoxy.

6. The method of claim 5, wherein the metal is selected from the group consisting of titanium, platinum, iridium, stainless steel, steel, titanium nitride, a titanium-aluminum-vanadium alloy, tungsten carbide, copper, and combination thereof.

7. The method of claim 1, wherein the work-piece substrate is selected from the group consisting of a semiconductor material, metal, and combination thereof.

8. The method of claim 1, wherein the forming the criss-cross pattern is accomplished using EDM.

9. The method of claim 1, further comprising mounting a back surface of the work-piece substrate on a top surface of a support substrate with a conductive material sandwiched between the work-piece substrate and the support substrate;

10. The method of claim 9, wherein mounting the back surface of the work-piece substrate on the top surface of the support substrate further comprises adhering the work-piece substrate to the support substrate with an epoxy on a perimeter interface of the work-piece substrate and the top surface of the support substrate.

11. The method of claim 10, wherein the epoxy is a conductive material.

12. The method of claim 1, wherein the forming the criss-cross pattern is accomplished using EDM.

13. The method of claim 12, wherein the forming includes a two-step process of a first rough cut step and a second finishing step.

14. The method of claim 1, wherein the height of one of the shaped columns is between 1.5 mm and 2 cm with a spacing between adjacent shaped columns is from 50 μ

m to 150 μ

m at a base of the shaped column before etching.

15. The method of claim 1, wherein the plurality of columns have an aspect ratio from about 10 to about 20.

16. The method of claim 1, wherein the tapering profile extends at least 90% of the length.

17. The method of claim 16, wherein the tapering profile extends substantially to the base.

18. The method of claim 1, wherein forming the channels on the work-piece substrate creates at least two adjacent shaped columns of varying heights.

19. The method of claim 1, wherein etching the plurality of shaped columns uses an etchant solution selected from the group consisting of a chemical etchant, an electrochemical etchant, and combination thereof.

21. The three-dimensional array of micro electrodes of claim 18, wherein a height of one of the shaped columns is between 3 mm and 10 mm.

20. A three-dimensional array of microelectrodes, comprising:

a base of rigid material; and

a plurality of shaped electrically conductive columns having tapered tips protruding from the base, wherein the shaped electrically conductive columns are electrically isolated from each other at the base by a dielectric material, and wherein a height of one of the shaped columns is between 1.5 mm and 2 cm with a distance between tips of the shaped electrically conductive columns from 100 μ

m to 400 μ

m.