Hybrid diamond-polymer thin film sensors and fabrication method

Patent metadata

Field	Value
Publication number	US-10667709-B2
Application number	US-201716301915-A
Country	US
Kind code	B2
Filing date	May 26, 2017
Priority date	May 27, 2016
Publication date	Jun 2, 2020
Grant date	Jun 2, 2020

Abstract

An implantable device is provided. The implantable device includes a flexible polymeric substrate that extends through an aperture in an electrically conductive material to form an anchor that partially covers the electrically conductive material. Methods for fabricating the implantable device are also provided.

First claim

What is claimed is:

1. A method of fabricating a flexible device, the method comprising:
generating a layer of SiO 2 on a surface of a substrate;
disposing a layer of an electrically conductive material on the layer of SiO 2 ;
removing a portion of the layer of an electrically conductive material to define a pattern in the remaining electrically conductive material, wherein the pattern includes a plurality of apertures that extend through the electrically conductive material and optionally through the layer of SiO 2 to the substrate;
applying an etching compound into the apertures and etching the SiO 2 vertically downward to the Si substrate when the apertures do not extend through the layer of SiO 2 and etching a portion of the layer of SiO 2 horizontally beneath the electrically conductive material to form a plurality of undercuts;
disposing a flexible polymeric material over the electrically conductive material, wherein the flexible polymeric material fills the undercuts and covers the electrically conductive material; and
removing the substrate and the remainder of the SiO 2 by etching to generate the flexible device.

2. The method according to claim 1 , wherein the substrate comprises silicon (Si), glass, or GaAs.

3. The method according to claim 1 , wherein the electrically conductive material comprises boron doped polycrystalline diamond (BDD).

4. The method according to claim 1 , wherein the layer of an electrically conductive material has a thickness of from about 0.25 μm to about 10 μm.

5. The method according to claim 1 , wherein the flexible polymeric material is parylene-C.

6. The method according to claim 1 , wherein the flexible polymeric material has a thickness of from about 1 μm to about 50 μm.

7. The method according to claim 1 , wherein the removing the substrate and the remainder of the SiO 2 by etching comprising etching with potassium hydroxide (KOH), tetramethylammonium hydroxide (TMAH), or HF/nitric/acetic acid (HNA).

8. The method according to claim 1 , further comprising at least one of chemically modifying at least a portion of the electrically conductive material, disposing a ligand to at least a portion of the electrically conductive material, or disposing a thin film over at least a portion of the electrically conductive material.

9. The method according to claim 1 , further comprising attaching components to the electrically conductive material, wherein the components are selected from the group consisting of contact pads, contacts, light emitting diodes (LEDs), micro LEDs (μLEDs), wires, and combinations thereof.

10. The method according to claim 1 , wherein the flexible device is a brain implant.

11. The method according to claim 1 , wherein the removing a portion of the layer of an electrically conductive material is performed by photolithography.

12. The method according to claim 11 , wherein the photolithography comprises:
disposing a metal layer onto the layer of an electrically conductive material, wherein the metal layer comprises aluminum (Al), copper (Cu), or gold (Au);
disposing a layer of photoresist on the metal layer;
disposing a ultraviolet light (UV)-transparent mask on the layer of photoresist, wherein the UV-transparent mask comprises a pattern that is not UV-transparent;
and exposing the UV-transparent mask to UV light.

13. The method according to claim 11 , wherein the photolithography is performed by a lift-off method.

14. A method of fabricating a flexible device, the method comprising:
generating a layer of SiO 2 on a surface of a silicon (Si) substrate;
disposing a layer of boron doped polycrystalline diamond (BDD) on the layer of SiO 2 ;
removing a portion of the BDD to define a pattern in the remaining BDD, wherein the pattern includes a plurality of apertures that extend through the BDD and optionally through the layer of SiO 2 to the substrate;
applying an etching compound into the apertures and etching the SiO 2 vertically downward to the Si substrate when the apertures do not extend through the layer of SiO 2 and etching a portion of the layer of SiO 2 horizontally beneath the electrically conductive material to form a plurality of undercuts;
disposing parylene-C over the BDD, wherein the parylene-C fills the undercuts and covers the BDD;
removing a portion of the parylene-C located above the BDD;
inverting the device and removing a top portion of the parylene-C and substantially all of the Si substrate;
inverting the device and removing the remainder of the SiO 2 ;
disposing additional parylene-C over top and bottom surfaces of the BDD by chemical vapor deposition;
and removing the parylene-C disposed on the top surface of the BDD.

15. The method according to claim 14 , wherein the flexible device is a sensor comprising a working electrode, a counter electrode, and a reference electrode.

16. The method according to claim 15 , wherein the method further comprises:
at least one of chemically modifying at least the working electrode, disposing a ligand to at least the working electrode, and disposing a thin film over at least the working electrode.

17. The method according to claim 15 , wherein the flexible device is configured to be implanted in neural tissue.

18. A method of fabricating a flexible device, the method comprising:
generating a layer of SiO 2 on a surface of a substrate;
placing a layer of an electrically conductive material comprising boron doped polycrystalline diamond on the layer of SiO 2 ;
removing a portion of the electrically conductive material to define a pattern in the remaining electrically conductive material;
etching a portion of the layer of SiO 2 horizontally beneath the electrically conductive material to form at least one undercut;
placing a flexible polymeric material over the electrically conductive material to fill the at least one undercut and cover the electrically conductive material; and
removing the substrate and the remainder of the SiO 2 by etching to create the flexible device.

19. The method according to claim 18 , wherein the flexible substrate comprises silicon (Si), glass, or GaAs, and the pattern includes a plurality of apertures that extend through the electrically conductive material, and the method further comprises applying an etching compound into the apertures.

20. The method according to claim 18 , wherein the removing the portion of the electrically conductive material is performed by photolithography.

21. The method according to claim 18 , further comprising attaching components to the electrically conductive material, wherein the components comprise at least one of: contact pads, contacts, light emitting diodes (LEDs), micro LEDs (μLEDs), wires, or combinations thereof.

22. The method according to claim 18 , wherein the flexible device is a mammalian implantable sensor or probe.

23. A flexible device comprising:
an electrically conductive material that defines a predetermined pattern, wherein the pattern includes at least one aperture that extends from a first surface of the electrically conductive material to a second opposing surface of the electrically conductive material; and
a flexible polymeric substrate,
wherein the second surface of the electrically conductive material is disposed on the flexible polymer substrate and the flexible polymeric substrate extends through the at least one aperture from the second surface to the first surface and extends radially on the first surface about

Assignees

• Univ Michigan State
• Fraunhofer Usa

Inventors

• Li Wen
• Fan Bin
• Rechenberg Robert
• Becker Michael
• Rusinek Cory

Classifications

• B81B2201/0214

  Biosensors; Chemical sensors · CPC title

• H01L21/3065

  Electricity · mapped topic

• A61B5/04001 Primary

  Human Necessities · mapped topic

• B81B2203/04

  Electrodes · CPC title

• H01L21/32137

  Electricity · mapped topic