ELECTRODE COMPOSITIONS FOR USE WITH ANALYTE SENSORS

• US 20120190950A1
• Filed: 01/20/2011
• Published: 07/26/2012
• Est. Priority Date: 01/20/2011
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Yang, Qingling, Shah, Rajiv, Li, Xiaolong, Pham, Barry Phong, Li, Yiwen
• Granted Patent: US 8,808,532 B2
• Time in Patent Office: Days
• US Class Current: 600/345
• CPC Class Codes: C12Q 1/001 Enzyme electrodes
• CPC Class Codes: C12Q 1/005 involving specific analytes or enzymes including groups of enzymes, e.g. oxydases; C12Q1/004 takes precedence

Abstract

Embodiments of the invention provide amperometric analyte sensors having optimized elements such as electrodes formed from sputtered platinum compositions as well as layers of material selected to optimize the characteristics of a wide variety of sensor elements and sensors. While embodiments of the innovation can be used in a variety of contexts, typical embodiments of the invention include glucose sensors used in the management of diabetes.

Claims

1. An amperometric analyte sensor apparatus comprising:

a base layer;

a conductive layer disposed on the base layer and comprising a working electrode, wherein the working electrode comprises a sputtered platinum composition;

an electrolyte retaining layer in operable contact with the conductive layer, wherein the electrolyte retaining layer is formed from a composition selected to absorb 10% to 50% water by weight;

an analyte modulating layer disposed over the conductive layer.

2. The analyte sensor apparatus of claim 1, wherein the sputtered platinum composition exhibits a root-mean-square roughness value below 3 nanometers.

3. The analyte sensor apparatus of claim 1, wherein the electrolyte retaining layer is not more than 3, 4, 5, 6 or 7 μ

m thick.

4. The analyte sensor apparatus of claim 1, wherein the electrolyte retaining layer comprises glucose oxidase entrapped within a poly(vinyl alcohol)-styrylpyridinium matrix so as to function as an analyte sensing layer;

and is at least 5, 6, 7, 8, 9 or 10 μ

m thick.

5. The analyte sensor apparatus of claim 1 further comprising an interference rejection membrane that inhibits the diffusion therethrough of compounds having a molecular weight greater than 140 Daltons.

6. The analyte sensor apparatus of claim 1, wherein the electrolyte retaining layer further functions as an interference rejection membrane that inhibits the diffusion therethrough of compounds having a molecular weight greater than 140 Daltons.

7. The analyte sensor apparatus of claim 1, wherein the analyte modulating layer comprises a blended mixture of a linear polyurethane/polyurea polymer and a branched acrylate polymer blended together at a ratio of between 1:

1 and 1;

20 by weight %.

8. The analyte sensor apparatus of claim 7, wherein the analyte modulating layer comprises a blended mixture of:

(1) a polyurethane/polyurea polymer formed from a mixture comprising;

(a) a diisocyanate;

(b) a hydrophilic polymer comprising a hydrophilic diol or hydrophilic diamine; and

(c) a siloxane having an amino, hydroxyl or carboxylic acid functional group at a terminus; and

(2) a branched acrylate polymer formed from a mixture comprising;

(a) a butyl, propyl, ethyl or methyl-acrylate;

(b) an amino-acrylate;

(c) a siloxane-acrylate; and

(d) a poly(ethylene oxide)-acrylate.

9. The analyte sensor apparatus of claim 1, wherein the analyte modulating layer exhibits a permeability to glucose that changes less than 2% per degree centigrade over a temperature range of 22 to 40 degrees centigrade.

10. The analyte sensor apparatus of claim 1, further comprising at least one of:

an analyte sensing layer;

a protein layer;

an adhesion promoting layer disposed over the analyte sensing layer, wherein the adhesion promoting layer promotes the adhesion between the analyte sensing layer and an adjacent layer;

or

a cover layer disposed over the analyte sensor apparatus, wherein the cover layer comprises an aperture positioned on the cover layer so as to facilitate an analyte present in the mammal contacting and diffusing through an analyte modulating layer; and

contacting the analyte sensing layer.

11. The analyte sensor apparatus of claim 1, wherein the analyte sensor apparatus is formed from biocompatible materials and exhibits an architecture compatible with implantation within a mammal.

12. A method of making a sensor apparatus for implantation within a mammal comprising the steps of:

providing a base layer;

forming a conductive layer on the base layer, wherein the conductive layer includes a working electrode formed from a sputtered platinum composition;

forming an electrolyte retaining layer in operable contact with the conductive layer, wherein the electrolyte retaining layer is formed from a composition selected to absorb 10% to 50% water by weight;

forming an analyte sensing layer disposed over the conductive layer; and

forming an analyte modulating layer disposed over the analyte sensing layer.

13. The method of claim 12, wherein the analyte sensing layer comprises glucose oxidase entrapped within a poly(vinyl alcohol)-styrylpyridinium (PVA-SbQ) polymer matrix.

14. The method of claim 13, further comprising modifying a surface of the analyte sensing layer using a plasma deposition process so that chemical moieties on the surface are crosslinked.

15. The method of claim 12, further comprising:

forming an interference rejection membrane on the working electrode, wherein the interference rejection membrane comprises crosslinked methacrylate polymers or crosslinked primary amine polymers;

forming the analyte sensing layer to include a first concentration of glucose oxidase is between 35KU/mL and 55KU/mL, a second concentration of glucose oxidase between 30KU/mL and 55KU/mL, and a third concentration of glucose oxidase between 5KU/mL and 15KU/mL;

forming a protein layer on the analyte sensing layer;

forming an adhesion promoting layer on the analyte sensing layer or the optional protein layer; and

/or

forming a cover layer disposed on at least a portion of the analyte modulating layer, wherein the cover layer further includes an aperture over at least a portion of the analyte modulating layer.

16. The method of claim 15, wherein the crosslinked methacrylate polymers comprise Poly(2-hydroxyethyl methacrylate) (pHEMA) polymers having an average molecular weight of between 100 and 1000 kilodaltons.

17. The method of claim 16, wherein the polymers are crosslinked by a hydrophilic crosslinking agent.

18. The method of claim 12, wherein the analyte modulating layer is formed to comprise a blended mixture of:

(1) a polyurethane/polyurea polymer formed from a mixture comprising;

(a) a diisocyanate;

(b) a hydrophilic polymer comprising a hydrophilic diol or hydrophilic diamine; and

(c) a siloxane having an amino, hydroxyl or carboxylic acid functional group at a terminus; and

(2) a branched acrylate polymer formed from a mixture comprising;

(a) a butyl, propyl, ethyl or methyl-acrylate;

(b) an amino-acrylate;

(c) a siloxane-acrylate; and

(d) a poly(ethylene oxide)-acrylate.

19. The method of claim 12, wherein the analyte modulating layer is formed to exhibit a permeability to glucose that changes less than 2% per degree centigrade over a temperature range of 22 to 40 degrees centigrade.

20. A composition of matter comprising:

a sputtered platinum composition; and

hydrophilic polymer composition comprising;

(a) crosslinked Poly(2-hydroxyethyl methacrylate) polymers having an average molecular weight between 100 and 1000 kilodaltons;

(b) crosslinked primary amine polymers having an average molecular weight between 4 and 500 kilodaltons;

or

(c) crosslinked poly(vinyl alcohol)-styrylpyridinium (PVA-SbQ) polymers.