ELECTROCHEMICAL TEST SENSOR

• US 20060219551A1
• Filed: 11/01/2004
• Published: 10/05/2006
• Est. Priority Date: 03/07/2002
• Status: Active Grant

• Current Assignee: Ascensia Diabetes Care Holdings AG (PHC Holdings Corporation)
• Original Assignee: Bayer Healthcare LLC (Bayer AG)
• Inventors: Edelbrock, Andrew J., Vreeke, Mark S., Musho, Matthew K.
• Granted Patent: US 7,118,668 B1
• Time in Patent Office: Days
• US Class Current: 204/403.140
• CPC Class Codes: A61M 2230/201 Glucose concentration
• CPC Class Codes: C12Q 1/001 Enzyme electrodes
• CPC Class Codes: C12Q 1/004 mediator-assisted
• CPC Class Codes: G01N 27/3274 Corrective measures, e.g. error detection, compensation for temperature or hematocrit, calibration coding of calibration information G01N33/48771

Abstract

Disclosed is an electrochemical sensor for the determination of analytes in body fluids, e.g. glucose in blood. The sensor involves a non-conductive base which provides a flow path for the body fluid with the base having a working and counter electrode on its surface which are in electrical communication with a detector of current. The base and a cover therefore provide a capillary space containing the electrodes into which the body fluid is drawn by capillary action. The counter electrode has a sub-element which contains an electroactive material and is configured in the system (sensor and meter) to provide an error signal when insufficient body fluid is drawn into the capillary.

Claims

1-10. -10. (canceled)

11. An electrochemical test sensor for detecting the concentration of an analyte in a fluid test sample, the test sensor comprising:

a non-conductive base that provides a flow path for the fluid test sample, the base including a counter electrode, a working electrode and a sub-element on an upper surface thereof, the counter and working electrodes being adapted to be in electrical communication with a detector of electrical current, the sub-element being physically disconnected from the counter electrode, the sub-element comprising an electroactive material that is adapted to allow oxidation to occur at the surface of the working electrode under an applied potential;

a reaction layer on at least the surface of the working electrode, the reaction layer comprising an enzyme; and

a cover coupled with the non-conductive base and forming a capillary space with an opening for the introduction of the fluid test sample thereto, the space forming a flow path for the fluid test sample,

wherein the sub-element of the counter electrode is located upstream from the working electrode relative to the opening such that when electrochemical communication occurs between only the sub-element and the working electrode there is insufficient flow of electrical current through a detector to constitute a valid determination of the analyte concentration in the fluid test sample.

12. The test sensor of claim 11 further comprising an insulating layer, the insulating layer exposing a portion of the sub-element to the reaction layer.

13. The test sensor of claim 11 wherein the reaction layer further comprises a mediator.

14. The test sensor of claim 13 wherein the mediator is ferricyanide.

15. The test sensor of claim 11 wherein the reaction layer further comprises poly(ethylene) oxide.

16. The test sensor of claim 11 wherein the enzyme is glucose oxidase.

17. The test sensor of claim 11 wherein the electroactive material is an oxide of Ag, Cu, Mn, Pb, Hg, Ni, Co, Bi, Re, or Te.

18. The test sensor of claim 17 wherein the electroactive material is AgO.

19. The test sensor of claim 11 wherein the electroactive material is a metal halide.

20. The test sensor of claim 11 wherein the cover has a concave portion, the concave portion forming the capillary space when the cover is coupled with the non-conductive base.

21. The test sensor of claim 11 further including a spacer element with a U-shaped indentation, the U-shaped indentation being located between the cover and the non-conductive base and forming the capillary space.

22. The test sensor of claim 11 wherein a major portion of the counter electrode is located downstream relative to the opening and at least a portion of the working electrode.

23. The test sensor of claim 11 wherein the area of the subelement is less than the area of the working electrode.

24. An electrochemical test sensor adapted to assist in determining the concentration of an analyte in a fluid test sample, the test sensor comprising:

a base assisting in forming an opening for introducing the fluid test sample;

a working electrode being coupled to the base;

a counter electrode being coupled to the base, the counter electrode and the working electrode being adapted to be in electrical communication with a detector of electrical current, a portion of the counter electrode being located downstream relative to the opening and at least a portion of the working electrode; and

a sub-element being coupled to the base, the sub-element being physically disconnected from the counter electrode, the sub-element comprising an electroactive material that is adapted to allow oxidation to occur at the surface of the working electrode under an applied potential, the sub-element of the counter electrode being located upstream from the working electrode relative to the opening such that when electrochemical communication occurs between only the sub-element and the working electrode there is insufficient flow of electrical current through a detector to constitute a valid determination of the analyte concentration in the fluid test sample.

25. The test sensor of claim 24 further comprising a cover adapted to be coupled to the base to form a capillary space, the capillary space having an opening for introducing the fluid test sample therein, the capillary space forming a flow path for the fluid test sample, the working electrode and the counter electrode being situated in the flow path.

26. The test sensor of claim 25 wherein the cover has a concave portion, the concave portion forming the capillary space when the cover is coupled with the base.

27. The test sensor of claim 25 further including a spacer element with a U-shaped indentation, the U-shaped indentation being located between the cover and the base and forming the capillary space.

28. The test sensor of claim 24 further comprising a reaction layer located on the surface of at least the working electrode, the reaction layer comprising an enzyme adapted to react with the analyte.

29. The test sensor of claim 24 wherein the reaction layer further comprises poly(ethylene) oxide.

30. The test sensor of claim 24 wherein the enzyme is glucose oxidase.

31. The test sensor of claim 24 wherein the electroactive material is an oxide of Ag, Cu, Mn, Pb, Hg, Ni, Co, Bi, Re, or Te.

32. The test sensor of claim 24 wherein the electroactive material is a metal halide.

33. A method of determining whether a sufficient quantity of a fluid test sample has been introduced to an electrochemical test sensor, the method comprising the acts of:

providing the electrochemical test sensor adapted to assist in determining the concentration of an analyte in a fluid test sample, the sensor comprising a base, a working electrode, a counter electrode and a sub-element, the base assisting in forming an opening for introducing the fluid test sample, the working electrode being coupled to the base, the counter electrode being coupled to the base, the counter electrode and the working electrode being adapted to be in electrical communication with a detector of electrical current, at least a portion of the counter electrode being located downstream relative to the opening and at least a portion of the working electrode, the sub-element being coupled to the base, the sub-element being physically disconnected from the counter electrode, the sub-element comprising an electroactive material that is adapted to allow oxidation to occur at the surface of the working electrode under an applied potential, the sub-element of the counter electrode being located upstream from the working electrode relative to the opening such that when electrochemical communication occurs between only the sub-element and the working electrode there is insufficient flow of electrical current through a detector to constitute a valid determination of the analyte concentration in the fluid test sample;

introducing the fluid test sample to the test sensor; and

determining whether a sufficient quantity of the fluid test sample has been introduced and, if not, notifying a user that an insufficient quantity of the fluid test sample has been introduced.

34. The method of claim 33, wherein the test sensor further comprises a cover adapted to be coupled to the base to form a capillary space, the capillary space having an opening for introducing the fluid test sample therein, the capillary space forming a flow path for the fluid test sample, the working electrode and the counter electrode being situated in the flow path.

35. The method of claim 34 wherein the cover has a concave portion, the concave portion forming the capillary space when the cover is coupled with the base.

36. The method of claim 34 further including a spacer element with a U-shaped indentation, the U-shaped indentation located between the cover and the base and forming the capillary space.

37. The method of claim 33 wherein the test sensor further comprises a reaction layer located on the surface of at least the working electrode, the reaction layer comprising an enzyme adapted to react with the analyte.

38. The method of claim 33 wherein the electroactive material is an oxide of Ag, Cu, Mn, Pb, Hg, Ni, Co, Bi, Re, or Te.

39. The method of claim 33 wherein the electroactive material is a metal halide.

40. The method of claim 33 wherein the analyte is glucose.