Electrochemical-sensor design

• US RE44,521 E1
• Filed: 10/23/2008
• Issued: 10/08/2013
• Est. Priority Date: 08/02/1999
• Status: Expired due to Fees

• Current Assignee: Ascensia Diabetes Care Holdings AG (PHC Holdings Corporation)
• Original Assignee: Bayer Healthcare LLC (Bayer AG)
• Inventors: Musho, Matthew K., Noell, J. Oakey, Edelbrock, Andrew J., Huang, Dijia
• Primary Examiner(s): Noguerola, Alex
• Application Number:
  US12/257,031
• Time in Patent Office: 1,811 Days
• Field of Search: 20440301-40315, 205/777.5, 205/778, 205/792, 205/775
• US Class Current: 205/775
• CPC Class Codes: C12Q 1/001 Enzyme electrodes
• 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

An electrochemical test sensor adapted to assist in determining the concentration of analyte in a fluid sample is disclosed. The sensor comprises a base that assists in forming an opening for introducing the fluid sample, a working electrode being coupled to the base, and 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, and a sub-element being coupled to the base. A major portion of the counter electrode is located downstream relative to the opening and at least a portion of the working electrode. The sub-element is located upstream relative to the working electrode such that when electrical communication occurs between only the sub-element and the working electrode there is insufficient flow of electrical current through the detector to determine the concentration of the analyte in the fluid sample.

Claims

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

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

a working electrode with an exposed portion not insulated from sample by dielectric material 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; and

a sub-element being coupled to the base, a major portion of the counter electrode being located downstream relative to the opening and at least a the exposed portion of the working electrode, the sub-element being located upstream relative to the working electrode such that when electrical communication occurs between only the sub-element and the working electrode there is insufficient flow of electrical current through the detector to determine the concentration of the analyte in the fluid test sample a first current profile is produced in response to electrical communication between the sub-element and the working electrode, and a second current profile is produced in response to electrical communication between the sub-element, the major portion of the counter electrode, and the working electrode, the first current profile being indicative of a short fill.

2. The sensor of claim 1 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.

3. The sensor of claim 2, wherein the cover includes an air vent.

4. The sensor of claim 1 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 to produce electrons, the electrons being adapted to be transferred to the working electrode.

5. The sensor of claim 1, wherein the area of the sub-element is less than 10% of the area of the working electrode.

6. The sensor of claim 1, wherein the sub-element and the counter electrode are physically connected.

7. 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 that assists in forming an opening for introducing the fluid test sample, a working electrode with an exposed portion not insulated from sample by dielectric material being coupled to the base, a counter electrode being coupled to the base, and a sub-element being coupled to the base, a major portion of the counter electrode being located downstream relative to the opening and at least a the exposed portion of the working electrode, the sub-element being located upstream relative to the working electrode;

introducing the fluid test sample to the test sensor; and

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

8. The method of claim 7 further comprising, prior to the act of determining whether a sufficient quantity of the fluid test sample has been introduced to the electrochemical test sensor, measuring current at a plurality of time periods to obtain a plurality of current measurements.

9. The method of claim 8 further comprising providing a current to initiate a test sequence prior to the act of measuring current at a plurality of time periods.

10. The method of claim 8 further comprising, prior to after the act of measuring current at a plurality of time periods, the acts of:

converting the plurality of current measurements into a plurality of error checking parameters; and

comparing the plurality of error checking parameters with their corresponding tolerance ranges.

11. The method of claim 10 wherein the act of notifying a user that an insufficient quantity of the fluid test sample has been introduced occurs when one or more of the plurality of error checking parameters are outside of their corresponding tolerance ranges.

12. The method of claim 11, wherein one or more of the plurality of error checking parameters is outside of its corresponding tolerance range when the fluid test sample fails to contact a major portion of the counter electrode.

13. The method of claim 10, wherein the plurality of error checking parameters is derived from the plurality of current measurements.

14. The method of claim 7, wherein the act of applying the fluid test sample to the sensor electrically connects the sub-element to the working electrode.

15. The method of claim 7, wherein the act of notifying a user that an insufficient quantity of the fluid test sample has been introduced includes providing an error signal.

16. The method of claim 7, 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.

17. The method of claim 16, wherein the cover includes an air vent.

18. The method of claim 7, 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 to produce electrons, the electrons being adapted to be transferred to the working electrode.

19. The method of claim 7, wherein the area of the sub-element is less than 10% of the area of the working electrode.

20. The method of claim 7, wherein the sub-element and the counter electrode are physically connected.

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

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

a working electrode with an exposed portion not insulated from sample by dielectric material 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; and

a sub-element being coupled to the base, a portion of the counter electrode being located downstream relative to the opening and the exposed portion of the working electrode, the sub-element being located upstream relative to the working electrode such that a first current profile is produced in response to electrical communication between the sub-element and the working electrode, and a second current profile is produced in response to electrical communication between the sub-element, the portion of the counter electrode, and the working electrode, the first current profile being indicative of a short fill.

22. The sensor of claim 21 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.

23. The sensor of claim 22, wherein the cover includes an air vent.

24. The sensor of claim 21 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 to produce electrons, the electrons being adapted to be transferred to the working electrode.

25. The sensor of claim 21, wherein the area of the sub-element is less than 10% of the area of the working electrode.

26. The sensor of claim 21, wherein the sub-element and the counter electrode are physically connected.

27. The electrochemical test sensor of claim 21, further comprising a reaction layer including an enzyme adapted to react with the analyte to produce electrons, the electrons being adapted to be transferred to the working electrode, the reaction layer being in contact with at least a portion of the working electrode, the reaction layer being removed from contact with the sub-element.

28. 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 that assists in forming an opening for introducing the fluid test sample, a working electrode with an exposed portion not insulated from sample by dielectric material being coupled to the base, a counter electrode being coupled to the base, and a sub-element being coupled to the base, a portion of the counter electrode being located downstream relative to the opening and the exposed portion of the working electrode, the sub-element being located upstream relative to the working electrode;

introducing the fluid test sample to the test sensor; and

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

29. The method of claim 28 further comprising, prior to the act of determining whether a sufficient quantity of the fluid test sample has been introduced to the electrochemical test sensor, measuring current at a plurality of time periods to obtain a plurality of current measurements.

30. The method of claim 29 further comprising providing a current to initiate a test sequence prior to the act of measuring current at a plurality of time periods.

31. The method of claim 29 further comprising, after the act of measuring current at a plurality of time periods, the acts of:

converting the plurality of current measurements into a plurality of error checking parameters; and

comparing the plurality of error checking parameters with their corresponding tolerance ranges.

32. The method of claim 31 wherein the act of notifying a user that an insufficient quantity of the fluid test sample has been introduced occurs when one or more of the plurality of error checking parameters are outside of their corresponding tolerance ranges.

33. The method of claim 32, wherein one or more of the plurality of error checking parameters is outside of its corresponding tolerance range when the fluid test sample fails to contact the portion of the counter electrode.

34. The method of claim 31, wherein the plurality of error checking parameters is derived from the plurality of current measurements.

35. The method of claim 28, wherein the act of applying the fluid test sample to the sensor electrically connects the sub-element to the working electrode.

36. The method of claim 28, wherein the act of notifying a user that an insufficient quantity of the fluid test sample has been introduced includes providing an error signal.

37. The method of claim 28, 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.

38. The method of claim 37, wherein the cover includes an air vent.

39. The method of claim 28, 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 to produce electrons, the electrons being adapted to be transferred to the working electrode.

40. The method of claim 28, wherein the area of the sub-element is less than 10% of the area of the working electrode.

41. The method of claim 28, wherein the sub-element and the counter electrode are physically connected.

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

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

a working electrode with an exposed portion not insulated from sample by dielectric material 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 sub-element being coupled to the base, a portion of the counter electrode being located downstream relative to the opening and the exposed portion of the working electrode, the sub-element being located upstream relative to the working electrode; and

a reaction layer including an enzyme adapted to react with the analyte to produce electrons, the electrons being adapted to be transferred to the working electrode, the reaction layer being in contact with at least a portion of the working electrode, the reaction layer being removed from contact with the sub-element such that when electrical communication occurs between only the sub-element and the working electrode there is insufficient flow of electrical current through the detector to determine the concentration of the analyte in the fluid test sample.

43. The electrochemical test sensor of claim 42, wherein the area of the sub-element is less than 10% of the area of the working electrode.