Electrodes and their use in assays

• US 6,309,535 B1
• Filed: 07/19/1999
• Issued: 10/30/2001
• Est. Priority Date: 11/07/1996
• Status: Expired due to Term

• Current Assignee: Cambridge Sensors Limited
• Original Assignee: Cambridge Sensors Limited
• Inventors: Yon-Hin, Bernadette, Williams, Stephen Charles, Blair, Neil
• Primary Examiner(s): Tung, T.
• Assistant Examiner(s): NOGUEROLA, ALEXANDER STEPHAN
• Application Number:
  US09/297,717
• Time in Patent Office: 834 Days
• Field of Search: 205/794.5, 205/777.5, 204/403, 204/294
• US Class Current: 205/777.5
• CPC Class Codes: G01N 27/308 at least partially made of carbon

Abstract

An electrode comprises a non-conductive substrate and a conductive layer comprising, in a bonded matrix, graphite particles coated with a noble metal, and carbon particles, wherein the graphite particles are up to 20 μm is size and have a surface area of 1-50 m²/g. This electrode is capable of measuring low levels of analyte, e.g. glucose in sweat when convined with a layer containing glucose oxidase.

Claims

1. An electrode comprising a non-conductive substrate and a conductive layer positioned on the non-conductive substrate, the conductive layer comprising, in a bonded matrix, graphite particles coated with a noble metal, and uncoated carbon particles, wherein the graphite particles are up to 20 μ

m in size and have a surface area of 1-50 m²/g and the carbon particles have an average size of less than 1 μ

m.

2. An electrode according to claim 1, wherein the carbon particles are 5-70 nm in size, and have a surface area of less than 150 m²/g.

3. A electrode according to claim 2, wherein the noble metal is platinum.

4. An electrode according to claim 3, wherein the graphite particles are coated with 5-20% w/w of the metal.

5. An electrode according to claim 4, wherein the matrix is a cross-linked polymer.

6. An electrode according to claim 5, which additionally comprises a further layer, on the conductive layer, including an enzyme.

7. An electrode according to claim 1, wherein the noble metal is platinum.

8. An electrode according to claim 7, Wherein the graphite particles are coated with 5-20% w/w of the metal.

9. An electrode according to claim 8, wherein the matrix is a cross-linked polymer.

10. An electrode according to claim 9, which additionally comprises a further layer, on the conductive layer, including an enzyme.

11. An electrode according to claim 1, wherein the graphite particles are coated with 5-20% w/w of the metal.

12. An electrode according to claim 11, wherein the matrix is a cross-linked polymer.

14. An electrode according to claim 1, wherein the matrix is a cross-linked polymer.

15. An electrode according to claim 14, which additionally comprises a further layer, on the conductive layer, including an enzyme.

16. An electrode according to claim 1, which additionally comprises a further layer, on the conductive layer, including an enzyme.

19. An electrode according to claim 6, wherein the enzyme is glucose oxidase.

20. A method of amperometrically detecting glucose in a host comprising contacting the skin of the host with an electrode according to claim 19, collecting sweat from the host in the further layer including the glucose oxidase enzyme, permitting the sweat to react with the glucose oxidase enzyme to produce hydrogen peroxide, and amperometrically measuring the hydrogen peroxide produced as a measure of glucose in the host.

13. An electrode according to claimn 12, which additionally comprises a further layer, on the conductive layer, including an enzyme.

17. An electrode according to clain 16, which additionally comprises a separate conducting layer, capable of being heated.

18. An electrode according to claim 17, wherein the enzyme is glucose oxidase.