Method for determining the concentration of an analyte in a liquid sample using small volume samples and fast test times

• US 8,425,759 B2
• Filed: 01/11/2012
• Issued: 04/23/2013
• Est. Priority Date: 11/16/2001
• Status: Expired due to Term

• Current Assignee: Roche Diabetes Care Inc. (Roche Holding AG)
• Original Assignee: Roche Diagnostics Operations Incorporated (Roche Holding AG)
• Inventors: Wilsey, Christopher D.
• Primary Examiner(s): Noguerola, Alex
• Application Number:
  US13/348,309
• Publication Number:
  US 20120103834A1
• Time in Patent Office: 468 Days
• Field of Search: 20440301-40315, 205/77.5, 205/778, 205/777.5, 205/792
• US Class Current: 205/792
• CPC Class Codes: C12Q 1/001 Enzyme electrodes
• CPC Class Codes: C12Q 1/006 for glucose
• CPC Class Codes: G01N 27/307 Disposable laminated or multilayered electrodes G01N27/3272 takes precedence
• CPC Class Codes: G01N 27/3272 Test elements therefor, i.e. disposable laminated substrates with electrodes, reagent and channels optical biosensors G01N33/52
• CPC Class Codes: G01N 27/3273 Devices therefor, e.g. test element readers, circuitry details not specific to biochemical electrodes G01N33/4875
• CPC Class Codes: G01N 27/3275 Sensing specific biomolecules, e.g. nucleic acid strands, based on an electrode surface reaction

Abstract

Analytes in a liquid sample are determined by methods utilizing sample volumes of up to 1.0 μl and test times from about 4 to about 9 seconds after detection of the sample. The methods are preferably performed using small test strips including a sample receiving chamber filled with the sample by capillary action.

Claims

1. A method of determining the concentration of glucose in a blood sample, comprising:

providing a disposable biosensor test strip including a capillary chamber having a depth suitable for capillary flow of blood, and holding a volume of from about 0.2 μ

l to about 0.6 μ

l of the blood sample, working and counter or reference electrodes disposed within the capillary chamber, the working electrode including one or more electrically connected electrode elements having an aggregate width of about 100 μ

m to about 500 μ

m, and a reagent proximal to or in contact with at least the working electrode, the reagent including an enzyme and a mediator;

applying a blood sample containing glucose into the capillary chamber, the capillary chamber directing capillary flow of the blood sample into contact with the reagent to cause the blood sample to at least partially solubilize or hydrate the reagent, the glucose reacting with the reagent to produce an electroactive reaction product;

detecting the blood sample in the capillary chamber;

within about 6 seconds after said detecting, applying an electrooxidation assay potential to the working electrode;

electrooxidizing the electroactive reaction product at the working electrode, said electrooxidizing producing an assay current;

measuring the assay current at one or more times after applying the assay potential,

correlating the assay current measurement to the concentration of glucose in the blood sample, and

within the time period lasting from about 2 seconds to about 8 seconds after said detecting, providing a readout of the glucose concentration in the blood sample.

2. The method of claim 1 in which the capillary chamber holds a volume of about 0.3 μ

l.

3. The method of claim 1 in which the capillary chamber holds a volume of about 0.4 μ

l.

4. The method of claim 1 in which the working electrode has an aggregate width of about 250 μ

m to about 500 μ

m.

5. The method of claim 1 in which said applying comprises applying an electrooxidation assay potential within the time period lasting from about 3 seconds to about 6 seconds after said detecting, and said providing comprises providing a readout of the glucose concentration within a time period lasting from about 3 seconds to about 6 seconds after said detecting.

6. The method of claim 1 in which said measuring comprises measuring the assay current within the time period lasting from about 3 seconds to about 6 seconds after said detecting, and said providing comprises providing a readout of the glucose concentration within a time period lasting from about 3 seconds to about 6 seconds after said detecting.

7. The method of claim 1 in which said applying comprises applying an electrooxidation assay potential within the time period lasting from about 3 seconds to about 6 seconds following said detecting, said measuring comprises measuring the assay current within the time period lasting from about 3 seconds to about 6 seconds following said detecting, and said providing comprises providing a readout of the glucose concentration within a time period lasting from about 3 seconds to about 6 seconds after said detecting.

8. The method of claim 1 and which further includes, following said detecting, providing a delay period prior to application of an electrooxidation assay potential to the working electrode.

9. The method of claim 8 in which the delay period includes an open-circuit time during which no potential is applied to the working electrode.

10. The method of claim 8 in which the delay period comprises a delay period lasting 5 seconds or less following said detecting.

11. The method of claim 10 in which the delay period lasts 3 seconds or less, said applying comprises applying an electrooxidation assay potential within the time period lasting from about 3 seconds to about 6 seconds after said detecting, and said providing comprises providing a readout of the glucose concentration within a time period lasting from about 3 seconds to about 6 seconds after said detecting.

12. The method of claim 10 in which the delay period lasts 3 seconds or less, said measuring comprises measuring the assay current within the time period lasting from about 3 seconds to about 6 seconds after said detecting, and said providing comprises providing a readout of the glucose concentration within a time period lasting from about 3 seconds to about 6 seconds after said detecting.

13. The method of claim 10 in which the delay period lasts 3 seconds or less, said applying comprises applying an electrooxidation assay potential within the time period lasting from about 3 seconds to about 6 seconds following said detecting, said measuring comprises measuring the assay current within the time period lasting from about 3 seconds to about 6 seconds following said detecting, and said providing comprises providing a readout of the glucose concentration within a time period lasting from about 3 seconds to about 6 seconds after said detecting.

14. The method of claim 13 in which the electrooxidation assay potential is a DC potential.

15. The method of claim 14 in which the capillary chamber has a depth of 100 μ

m to 200 μ

m.

16. A method of determining the concentration of glucose in a blood sample, comprising:

providing a disposable biosensor test strip including a capillary chamber having a depth suitable for capillary flow of blood, and holding a volume of from about 0.2 μ

l to about 0.6 μ

l of the blood sample, working and counter or reference electrodes disposed within the capillary chamber, the working electrode including one or more electrically connected electrode elements having an aggregate area of 0.1 mm² to 0.5 mm², and a reagent proximal to or in contact with at least the working electrode, the reagent including an enzyme and a mediator;

applying a blood sample containing glucose into the capillary chamber, the capillary chamber directing capillary flow of the blood sample into contact with the reagent to cause the blood sample to at least partially solubilize or hydrate the reagent, the glucose reacting with the reagent to produce an electroactive reaction product;

detecting the blood sample in the capillary chamber;

within about 6 seconds after said detecting, applying an electrooxidation assay potential to the working electrode;

electrooxidizing the electroactive reaction product at the working electrode, said electrooxidizing producing an assay current;

measuring the assay current at one or more times after applying the assay potential,

correlating the assay current measurement to the concentration of glucose in the blood sample, and

within the time period lasting from about 2 to about 8 seconds after said detecting, providing a readout of the glucose concentration in the blood sample.

17. The method of claim 16 in which the capillary chamber holds a volume of about 0.3 μ

l.

18. The method of claim 16 in which the capillary chamber holds a volume of about 0.4 μ

l.

19. The method of claim 16 in which the working electrode has an aggregate width of about 250 μ

m to about 500 μ

m.

20. The method of claim 16 in which said applying comprises applying an electrooxidation assay potential within the time period lasting from about 3 seconds to about 6 seconds after said detecting, and said providing comprises providing a readout of the glucose concentration within a time period lasting from about 3 seconds to about 6 seconds after said detecting.

21. The method of claim 16 in which said measuring comprises measuring the assay current within the time period lasting from about 3 seconds to about 6 seconds after said detecting, and said providing comprises providing a readout of the glucose concentration within a time period lasting from about 3 seconds to about 6 seconds after said detecting.

22. The method of claim 16 in which said applying comprises applying an electrooxidation assay potential within the time period lasting from about 3 seconds to about 6 seconds following said detecting, said measuring comprises measuring the assay current within the time period lasting from about 3 seconds to about 6 seconds following said detecting, and said providing comprises providing a readout of the glucose concentration within a time period lasting from about 3 seconds to about 6 seconds after said detecting.

23. The method of claim 16 and which further includes, following said detecting, providing a delay period prior to application of an electrooxidation assay potential to the working electrode.

24. The method of claim 23 in which the delay period includes an open-circuit time during which no potential is applied to the working electrode.

25. The method of claim 23 in which the delay period comprises a delay period lasting 5 seconds or less following said detecting.

26. The method of claim 25 in which the delay period lasts 3 seconds or less, said applying comprises applying an electrooxidation assay potential within the time period lasting from about 3 seconds to about 6 seconds after said detecting, and said providing comprises providing a readout of the glucose concentration within a time period lasting from about 3 seconds to about 6 seconds after said detecting.

27. The method of claim 25 in which the delay period lasts 3 seconds or less, said measuring comprises measuring the assay current within the time period lasting from about 3 seconds to about 6 seconds after said detecting, and said providing comprises providing a readout of the glucose concentration within a time period lasting from about 3seconds to about 6 seconds after said detecting.

28. The method of claim 25 in which the delay period lasts 3 seconds or less, said applying comprises applying an electrooxidation assay potential within the time period lasting from about 3 seconds to about 6 seconds following said detecting, said measuring comprises measuring the assay current within the time period lasting from about 3 seconds to about 6 seconds following said detecting, and said providing comprises providing a readout of the glucose concentration within a time period lasting from about 3 seconds to about 6 seconds after said detecting.

29. The method of claim 28 in which the electrooxidation assay potential is a DC potential.

30. The method of claim 29 in which the capillary chamber has a depth of 100 μ

m to 200 μ

m.