Flux limiting membrane for intravenous amperometric biosensor

• US 20070202562A1
• Filed: 02/23/2007
• Published: 08/30/2007
• Est. Priority Date: 02/27/2006
• Status: Abandoned Application

• Current Assignee: Edwards Lifesciences Corporation
• Original Assignee: Edwards Lifesciences Corporation
• Inventors: Curry, Kenneth M.
• Application Number:
  US11/710,329
• Publication Number:
  US 20070202562A1
• Time in Patent Office: Days
• US Class Current: 435/14
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14865 invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors

Abstract

A flux limiting layer for an intravenous amperometric biosensor is formed on a substrate to limit a diffusion rate of an analyte from blood to an enzyme electrode. The layer may be formed from ethylene vinylacetate (EVA) dissolved in a solvent such as paraxylene, spray-coated to cover a portion of the electrode, and cured to seal the electrode to the substrate. In a glucose sensor having glucose oxidase disposed on the electrode, thickness and concentration of the EVA layer are optimized to promote a linear output of electrode current as a function of blood glucose concentration.

Claims

1. A flux limiting membrane for an intravenous amperometric biosensor, comprising:

an ethylene vinylacetate (EVA) polymer at least partially coating a reagent disposed on an electrode of the biosensor to limit a rate at which a reactant from blood diffuses to the reagent.

2. The flux limiting membrane of claim 1, wherein the reactant comprises glucose.

3. The flux limiting membrane of claim 1, wherein the EVA polymer is deposited from a solution comprising EVA dissolved in a solvent.

4. The flux limiting membrane of claim 3, wherein the solution comprises between about 0.5 wt % and about 6.0 wt % of an EVA composition.

5. The flux limiting membrane of claim 4, wherein the EVA composition has a vinyl acetate content between about 9 wt % and about 50 wt %.

6. The flux limiting membrane of claim 3, wherein the solvent is selected from the group comprising cyclohexanone, paraxylene, and tetrahydrofuran.

7. The flux limiting membrane of claim 1, wherein the EVA polymer comprises an average diffusion layer thickness between about 0.5 microns and about 10 microns.

8. The flux limiting membrane of claim 1, further comprising a biocompatibility layer.

9. The flux limiting membrane of claim 8, wherein the biocompatibility layer comprises heparin.

10. The flux limiting membrane of claim 1, further comprising poly(methylmethacrylate-co-butyl methacrylate) blended with the EVA polymer.

11. The flux limiting membrane of claim 1, wherein the EVA polymer is cross-linked with diglycidil ether.

12. The flux-limiting membrane of claim 1, wherein the EVA polymer is cross-linked with a diisocyanate.

13. An intravenous amperometric biosensor, comprising:

a substrate;

an electrode bonded to the substrate;

a reagent disposed on the electrode; and

an ethylene vinylacetate (EVA) flux limiting membrane at least partially coating the reagent to limit a rate at which a reactant from blood diffuses to the reagent.

14. The biosensor of claim 13, wherein the reagent comprises glucose oxidase and the reactant comprises glucose.

15. The biosensor of claim 13, wherein the EVA flux limiting membrane adheres to a portion of the electrode.

16. The biosensor of claim 13, wherein the EVA flux limiting membrane seals the electrode to the substrate.

17. The biosensor of claim 13, wherein the EVA flux limiting membrane is deposited from a solution comprising EVA dissolved in a solvent.

18. The biosensor of claim 17, wherein the solution comprises between about 0.5 wt % and about 6.0 wt % of an EVA composition.

19. The biosensor of claim 18, wherein the EVA composition has a vinyl acetate content between about 9 wt % and about 40 wt %.

20. The biosensor of claim 17, wherein the solvent is selected from the group comprising cyclohexanone, paraxylene, and tetrahydrofuran.

21. The biosensor of claim 13, wherein the EVA flux limiting membrane comprises an average diffusion layer thickness between about 0.5 microns and about 10 microns.

22. The biosensor of claim 13, further comprising poly(methylmethacrylate-co-butyl methacrylate) blended with the EVA flux limiting membrane.

23. The biosensor of claim 13, wherein the EVA flux limiting membrane is cross-linked with diglycidil ether.

24. The biosensor of claim 13, wherein the EVA flux limiting membrane is cross-linked with a diisocyanate.

25. On a biosensor having an enzyme electrode disposed on a substrate, a method for forming a flux limiting membrane on the enzyme electrode, comprising:

dissolving ethylene vinylacetate (EVA) in a solvent;

applying a layer of the dissolved EVA to an area of the substrate that includes at least a portion of the enzyme electrode; and

curing the applied layer.

26. The method of claim 25, wherein the solvent is selected from the group comprising cyclohexanone, paraxylene, and tetrahydrofuran.

27. The method of claim 25, wherein the dissolving step further comprises dissolving between about 0.5 wt % and about 6.0 wt % of an EVA composition in the solvent.

28. The method of claim 27, wherein the EVA composition has a vinyl acetate content between about 9 wt % and about 40 wt %.

29. The method of claim 25, wherein the applying step comprises spray-coating the EVA solution onto the area of the substrate.

30. The method of claim 25, wherein the applying step further comprises creating a layer of the EVA solution having a thickness between about 0.5 microns and about 10 microns.