High aspect ratio microelectrode arrays enabled to have customizable lengths and methods of making the same

• US 8,886,279 B2
• Filed: 06/03/2009
• Issued: 11/11/2014
• 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: Tathireddy, Prashant, Solzbacher, Florian
• Primary Examiner(s): Dvorak, Linda
• Assistant Examiner(s): Cardinal, Erin M
• Application Number:
  US12/996,356
• Publication Number:
  US 20120138335A1
• Time in Patent Office: 1,987 Days
• Field of Search: 600/378, 600/377, 600/393, 600544-545, 607116-118, 298/25, 295/921
• US Class Current: 600/378
• 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:

a) providing a substantially non-metal work-piece substrate;

b) forming a substantially criss-cross pattern of channels on a top surface of the substantially non-metal work-piece substrate to form a plurality of tapered columns each shaped by electrical discharge machining (EDM) to have a tapered tip and a base, wherein the tapered tips have a tapering profile which extends at least 50% of a height of the tapered columns; and

c) etching the plurality of tapered columns with an etchant capable of etching non-metals to sharpen the tapered tips into needle tips to form the array of microelectrodes.

2. The method of claim 1, further comprising:

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

b) filling the rectangular channels with a dielectric material prior to mounting the back surface of the substantially non-metal work-piece substrate on a top surface of a 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 forming the substantially criss-cross pattern of channels on the top surface of the substantially non-metal work-piece substrate.

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

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

6. The method of claim 5, wherein mounting the back surface of the substantially non-metal work-piece substrate on the top surface of the support substrate further comprises adhering the substantially non-metal work-piece substrate to the support substrate with an epoxy on a perimeter interface of the substantially non-metal work-piece substrate and the top surface of the support substrate.

7. The method of claim 6, wherein the epoxy is a conductive material.

8. The method of claim 1, wherein the forming of the tapering profile includes a two-step EDM process of a first rough cut step and a second finishing step.

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

m to 150 μ

m at the base of the tapered columns before etching.

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

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

12. The method of claim 11, wherein the tapering profile extends substantially to the base.

13. The method of claim 1, wherein forming the channels on the substantially non-metallic work-piece substrate creates at least two adjacent tapered columns of varying heights.

14. The method of claim 1, wherein the etchant capable of etching non-metals is an etchant solution selected from the group consisting of a chemical etchant, an electrochemical etchant, and combination thereof.

15. A three-dimensional array of microelectrodes formed by the method of claim 1 wherein:

the substantially non-metal work-piece substrate is further a rigid material; and

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

m to 400 μ

m.

16. The three-dimensional array of microelectrodes of claim 15, wherein the tapering profile extends at least 90% of the height.