Electrochemical Sensor for a Bandage Type of Continuous Glucose Monitoring System

• US 20160235346A1
• Filed: 02/15/2016
• Published: 08/18/2016
• Est. Priority Date: 02/16/2015
• Status: Abandoned Application

• Current Assignee: Verily Life Sciences LLC (Alphabet Inc.)
• Original Assignee: Verily Life Sciences LLC (Alphabet Inc.)
• Inventors: Liu, Zenghe, Otis, Brian, Wasson, Jaclyn Leverett, Biederman, William James
• Application Number:
  US15/043,817
• Publication Number:
  US 20160235346A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61B 2560/063 Devices specially adapted for delivering implantable medical measuring apparatus
• CPC Class Codes: A61B 2562/12 Manufacturing methods specially adapted for producing sensors for in-vivo measurements
• CPC Class Codes: A61B 2562/125 characterised by the manufacture of electrodes
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1459 invasive, e.g. introduced into the body by a catheter A61B5/1464 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: A61B 5/14865 invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors
• CPC Class Codes: A61B 5/6847 mounted on an invasive device
• CPC Class Codes: A61B 5/6849 in combination with a needle set
• CPC Class Codes: C25D 11/34 of metals or alloys not provided for in groups C25D11/04 - C25D11/32
• CPC Class Codes: C25D 3/02 from solutions C25D5/34 - C25D5/46 take precedence
• CPC Class Codes: C25D 3/46 of silver
• CPC Class Codes: C25D 5/02 Electroplating of selected surface areas
• CPC Class Codes: C25D 5/48 After-treatment of electroplated surfaces

Abstract

An electrochemical sensor of a flexible, body-mountable analyte sensing device is provided. The electrochemical sensor is disposed on a flexible sensor probe that is configured to penetrate the skin such that the electrochemical sensor disposed on the sensor probe can detect an analyte in interstitial fluid. The electrochemical sensor is made sensitive to the analyte by disposing a substance that selectively binds to reacts with, catalyzes a reaction of, or otherwise selectively interacts with the analyte. The substance is localized by crosslinking on the surface of an electrode and/or by being disposed in a polymer layer disposed on the electrode. The polymer layer can be a hydrogel. Further, a hydrogel layer can be formed on the sensor probe to protect elements of the sensor probe and to increase the biocompatibility of the sensor probe.

Claims

1. A sensor comprising:

a flexible substrate, wherein the flexible substrate is mountable to a skin surface, wherein the flexible substrate includes an elongate portion, wherein a distal end of the elongate portion is configured to extend beneath the skin surface to contact interstitial fluid; and

a first electrode and a second electrode, wherein the first electrode and second electrode are disposed at the distal end of the elongate portion of the flexible substrate, wherein the first electrode is selectively sensitive to an analyte in the interstitial fluid, and wherein the first electrode and second electrode are configured to detect the analyte electrochemically.

2. The sensor of claim 1, wherein the flexible substrate comprises polyimide.

3. The sensor of claim 1, wherein the flexible substrate has a thickness of less than approximately 100 microns.

4. The sensor of claim 1, wherein the elongate portion has a width between approximately 25 microns and approximately 400 microns.

5. The sensor of claim 1, wherein the elongate portion has a length between approximately 500 microns and approximately 6000 microns.

6. The sensor of claim 1, wherein the second electrode comprises a layer of silver and silver chloride disposed on the flexible substrate.

7. The sensor of claim 1, wherein the first electrode comprises a metal layer on the flexible substrate, wherein the first electrode further comprises a substance that selectively interacts with the analyte that is disposed on the metal electrode.

8. The sensor of claim 7, wherein the analyte is glucose, and wherein the substance that selectively interacts with the analyte is glucose oxidase.

9. The sensor of claim 7, wherein the substance that selectively interacts with the analyte comprises a crosslinked layer disposed on the metal layer.

10. The sensor of claim 7, wherein the substance that selectively interacts with the analyte is disposed in a polymer layer disposed on the metal layer, and wherein the polymer layer comprises 2-hydroxyethyl methacrylate units.

11. The sensor of claim 1, wherein the first electrode and the second electrode are disposed on opposite sides of the elongate portion of the flexible substrate.

12. The sensor of claim 1, further comprising an adhesive layer disposed on the flexible substrate.

13. A method comprising:

forming a first electrode and a second electrode on a flexible substrate, wherein the first electrode is selectively sensitive to an analyte in an interstitial fluid, wherein the first electrode and second electrode are configured to detect the analyte electrochemically; and

trimming the flexible substrate to form a first trimmed flexible substrate that includes an elongate portion, wherein a distal end of the elongate portion is configured to extend beneath a skin surface to contact interstitial fluid, wherein the first trimmed flexible substrate is mountable to the skin surface, and wherein trimming the flexible substrate to form the first trimmed flexible substrate comprises trimming the flexible substrate such that the first electrode and second electrode are located at the distal end of the elongate portion of the first trimmed flexible substrate.

14. The method of claim 13, further comprising:

forming a third electrode and a fourth electrode on the flexible substrate, wherein the third electrode is selectively sensitive to the analyte in an interstitial fluid, wherein the third electrode and fourth electrode are configured to detect the analyte electrochemically, wherein trimming the flexible substrate to form a first trimmed flexible substrate that includes an elongate portion comprises trimming the flexible substrate such that the third electrode and the fourth electrode are not located on the first trimmed flexible substrate; and

trimming the flexible substrate to form a second trimmed flexible substrate that includes an elongate portion, wherein a distal end of the elongate portion of the second trimmed flexible substrate is configured to extend beneath a skin surface to contact interstitial fluid, wherein the second trimmed flexible substrate is mountable to the skin surface, and wherein trimming the flexible substrate to form the second trimmed flexible substrate comprises trimming the flexible substrate such that the third electrode and fourth electrode are located at the distal end of the elongate portion of the second trimmed flexible substrate.

15. The method of claim 13, further comprising:

depositing conductive traces on the flexible substrate, wherein forming the first electrode and the second electrode on the flexible substrate comprises depositing the first electrode and the second electrode at least partially on the conductive traces.

16. The method of claim 15, wherein depositing the first electrode and the second electrode at least partially on the conductive traces comprises electroplating at least one of the first electrode and the second electrode on respective conductive traces.

17. The method of claim 13, wherein the second electrode comprises silver, and further comprising:

forming a silver chloride layer on the second electrode by anodic oxidation.

18. The method of claim 13, further comprising:

disposing an analyte-selective substance on the first electrode by crosslinking the analyte-selective substance on the first electrode using a crosslinking agent.

19. The method of claim 13, further comprising:

Forming a polymer layer on the first electrode, wherein the polymer layer comprises the analyte-selective substance and 2-hydroxyethyl methacrylate units, and wherein forming the polymer layer comprises depositing a solution comprising the analyte-selective substance and 2-hydroxyethyl methacrylate units and polymerizing the deposited solution.

20. The method of claim 13, further comprising:

forming an outer protective layer on the elongate portion of the flexible substrate, wherein the outer protective layer comprises a hydrogel, wherein forming the outer protective layer comprises depositing a solution comprising hydrogel monomer units on the elongate portion and polymerizing the deposited solution, and wherein depositing the solution on the elongate portion comprises dipping the elongate portion in the solution comprising hydrogel monomer units.