FLEXIBLE ELECTROCHEMICAL MICRO-SENSOR

• US 20150253276A1
• Filed: 03/07/2014
• Published: 09/10/2015
• Est. Priority Date: 03/07/2014
• Status: Active Grant

• Current Assignee: STMicroelectronics International N.V. (STMicroelectronics NV)
• Original Assignee: Stmicroelectronics Pte Limited (STMicroelectronics NV)
• Inventors: Le Neel, Olivier, Cherian, Suman, Leung, Calvin
• Granted Patent: US 9,918,667 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1468 using chemical or electrochemical methods, e.g. by polarographic means A61B5/1486 takes precedence
• CPC Class Codes: A61B 5/1473 invasive, e.g. introduced into the body by a catheter A61B5/1482 takes precedence
• CPC Class Codes: G01N 27/3272 Test elements therefor, i.e. disposable laminated substrates with electrodes, reagent and channels optical biosensors G01N33/52

Abstract

A universal electrochemical micro-sensor can be used either as a biosensor or an environmental sensor. Because of its small size and flexibility, the micro-sensor is suitable for continuous use to monitor fluids within a live subject, or as an environmental monitor. The micro-sensor can be formed on a reusable glass carrier substrate. A flexible polymer backing, together with a set of electrodes, forms a reservoir that contains an electrolytic fluid chemical reagent. During fabrication, the glass carrier substrate protects the fluid chemical reagent from degradation. A conductive micromesh further contains the reagent while allowing partial exposure to the ambient biological or atmospheric environment. The micromesh density can be altered to accommodate fluid reagents having different viscosities. Flexibility is achieved by attaching a thick polymer tape and peeling away the micro-sensor from the glass carrier substrate. The final structure is thereby transferred to the polymer tape, providing a flexible product.

Claims

1. A fluid electrochemical micro-sensor, comprising:

a plurality of photosensitive polymer films;

a volume of a fluid chemical reagent contained by at least the photosensitive polymer films, a portion of a surface area of the fluid chemical reagent being exposed to an ambient environment; and

electrodes at least partially embedded between the photosensitive polymer films and in contact with the fluid chemical reagent.

2. The fluid electrochemical micro-sensor of claim 1, further comprising a species inlet net partially covering the exposed portion of the fluid chemical reagent.

3. The fluid electrochemical micro-sensor of claim 1 wherein the surface area of the fluid chemical reagent exposed to the ambient environment is substantially circular.

4. The fluid electrochemical micro-sensor of claim 2 wherein the surface area of the fluid chemical reagent exposed to the ambient environment is defined by the species inlet net.

5. The fluid electrochemical micro-sensor of claim 4 wherein the species inlet net is a conductive micromesh.

6. The fluid electrochemical micro-sensor of claim 5 wherein dimensions of the conductive micromesh are based on a viscosity of the fluid chemical reagent.

7. The fluid electrochemical micro-sensor of claim 5 wherein the conductive micromesh is coupled to one or more of the electrodes.

8. The fluid electrochemical micro-sensor of claim 1 wherein each electrode is electrically coupled to a corresponding arc segment that partially surrounds the fluid chemical reagent.

9. The fluid electrochemical micro-sensor of claim 1 wherein the electrodes are made of a biocompatible conducting material.

10. The fluid electrochemical micro-sensor of claim 9 wherein the biocompatible conducting material includes one or more of gold, platinum, or carbon.

11. The fluid electrochemical micro-sensor of claim 1 wherein one or more of the photosensitive polymer films is polyimide.

12. The fluid electrochemical micro-sensor of claim 1 wherein the fluid chemical reagent includes one or more of an electrolyte or an enzyme.

13. The fluid electrochemical micro-sensor of claim 1 wherein the fluid chemical reagent is in the form of one or more of a gel, a liquid, or a paste.

14. The fluid electrochemical micro-sensor of claim 1 wherein the ambient environment is inside an organism and the fluid chemical reagent is biologically configured to react with blood of the organism.

15. The fluid electrochemical micro-sensor of claim 1 wherein the ambient environment is atmospheric and the fluid chemical reagent is a gas.

16. A method of fabricating a fluid electrochemical micro-sensors, the method comprising:

forming a first polymer layer on a rigid substrate, the polymer layer having openings patterned therein, the openings including a well opening;

forming metal electrodes corresponding to the openings;

forming traces coupling the metal electrodes;

forming a second polymer layer, the first and second polymer layers together forming sides of a well suitable for containing a fluid;

dispensing a volume of a fluid chemical reagent into the well;

laminating a polymer tape onto the micro-sensor;

singulating the micro-sensors; and

separating the micro-sensors from the rigid substrate.

17. The method of claim 16 wherein the rigid substrate is a glass carrier substrate.

18. The method of claim 16 wherein separating the micro-sensor from the substrate includes:

submerging the substrate in a water bath; and

peeling the polymer tape, together with the micro-sensor, off the substrate.

19. The method of claim 16 wherein the openings include contact holes.

20. The method of claim 16 wherein the well opening is substantially circular.

21. The method of claim 16 wherein singulating the sensors entails use of a laser beam.

22. The method of claim 16 wherein forming the metal electrode corresponding to the well opening entails forming one or more arc segments adjacent to a perimeter of the well opening.

23. The method of claim 16 wherein forming the metal electrode corresponding to the well opening further includes forming a metal micromesh over the well opening.