Biosensor

1. A device, comprising:

a foil layer;

an electrode layer positioned on the foil layer;

a first hydrogel layer positioned over the foil layer and having an opening through which a portion of the electrode layer is exposed; and

a second hydrogel layer positioned in the opening and in contact with the electrode layer, the second hydrogel layer including an immobilized bio-recognition element.

2. The device of claim 1 , further comprising:

an adhesive layer positioned between and in contact with the foil layer and the first hydrogel layer.

3. The device of claim 1 , wherein the opening in the first hydrogel layer is one of a plurality of openings in the first hydrogel layer through which respective portions of the electrode layer are exposed, and wherein the second hydrogel layer is in contact with the electrode layer through fewer than all of the plurality of openings in the first hydrogel layer.

4. The device of claim 1 , wherein the foil layer is a polymeric foil.

5. The device of claim 1 , wherein the electrode layer is a layer of an electrically conductive polymer.

6. The device of claim 1 , wherein the electrode layer comprises a titanium seed layer in contact with the foil layer and a gold layer positioned over the titanium seed layer.

7. A biosensor, comprising

a substrate;

an electrode layer over the substrate;

a first hydrogel layer positioned over the substrate and having a through-opening extending to the electrode layer; and

a second hydrogel layer positioned in the opening and in contact with the electrode layer, the second hydrogel layer including an immobilized bio-recognition element.

8. The biosensor of claim 7 , wherein the second hydrogel layer is arranged partly on and in direct contact with the first hydrogel layer and partly on and in direct contact with the electrode layer.

9. The biosensor of claim 7 , wherein the second hydrogel layer includes a first portion positioned in the opening and in contact with the electrode layer and a second portion positioned on the first hydrogel layer such that the first hydrogel layer is positioned between the second portion of the second hydrogel layer and the electrode layer.

10. The biosensor of claim 7 , further comprising:

a foil layer positioned on the substrate; and

an adhesive layer positioned over and in contact with the foil layer and between a part of the first hydrogel layer and the foil layer.

11. The biosensor of claim 10 , wherein the adhesive layer comprises silane.

12. The biosensor of claim 7 , wherein the bio-recognition element is an enzyme.

13. The biosensor of claim 7 , wherein at least one of the first and second photo-definable hydrogel membranes comprises at least one of oligomers and prepolymers.

14. The biosensor of claim 13 , wherein the at least one of oligomers and prepolymers is selected from a group consisting of:

15. A biosensor, comprising

a substrate;

an electrode layer over the substrate;

a first hydrogel layer positioned over the substrate and having a through-opening extending to the electrode layer; and

a second hydrogel layer positioned in the opening and in contact with the electrode layer, the second hydrogel layer including an immobilized bio-recognition element, wherein a portion of the first hydrogel layer is positioned between a portion of the second hydrogel layer and the electrode layer.

16. The biosensor of claim 15 , wherein the second hydrogel layer is arranged partly on and in direct contact with the first hydrogel layer and partly on and in direct contact with the electrode layer.

17. The biosensor of claim 15 , wherein the second hydrogel layer includes a first portion positioned in the opening and in contact with the electrode layer and a second portion positioned on the first hydrogel layer such that the first hydrogel layer is positioned between the second portion of the second hydrogel layer and the electrode layer.

18. The biosensor of claim 15 , further comprising:

a foil layer positioned on the substrate; and

an adhesive layer positioned over and in contact with the foil layer and between a part of the first hydrogel layer and the foil layer.

19. The biosensor of claim 15 , wherein the bio-recognition element is an enzyme.

20. The biosensor of claim 15 , wherein at least one of the first and second photo-definable hydrogel membranes comprises at least one of oligomers and prepolymers selected from a group consisting of PEG diacrylate, PEG diamethacrylate, polyproplylene fumerate-co-ethylene glycol, acrylic modified PVA, commutated hyaluronic acid, methacrylate-modified Dextran, and polyphosphazene.