METHOD FOR DETERMINING THE CONCENTRATION OF AN ANALYTE IN A LIQUID SAMPLE USING SMALL VOLUME SAMPLES AND FAST TEST TIMES

• US 20070161070A1
• Filed: 02/22/2007
• Published: 07/12/2007
• Est. Priority Date: 11/16/2001
• Status: Abandoned Application

• Current Assignee: Roche Diabetes Care Inc. (Roche Holding AG)
• Original Assignee: Roche Diabetes Care Inc. (Roche Holding AG)
• Inventors: Wilsey, Christopher
• Application Number:
  US11/677,737
• Publication Number:
  US 20070161070A1
• Time in Patent Office: Days
• US Class Current: 435/14
• 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 less than about 1.5 μl and test times within ten seconds. 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 an analyte in a liquid sample comprising:

providing a test sensor including a sample receiving cavity having a volume of less than about 1.5 μ

l, the sensor including at least one working electrode and at least one counter electrode disposed within the sample receiving cavity, the sensor further including a reagent layer comprising an enzyme and a mediator, the reagent layer being disposed on at least the working electrode, at least one of the enzyme and mediator being selected to react with the analyte to generate an electrochemical signal representative of the concentration of the analyte in the liquid sample;

admitting the liquid sample into the sample receiving cavity;

detecting the time at which the liquid sample enters the sample cavity;

following said detecting, controlling the voltage or current across the working and counter electrodes; and

within ten seconds of said detecting, obtaining a readout of the concentration of the analyte in the liquid sample.

2. The method of claim 1 in which the sample receiving cavity has a volume of less than or equal to about 1.0 μ

l.

3. The method of claim 1 in which the sample receiving cavity has a volume of between about 0.1 μ

l and about 1.5 μ

l.

4. The method of claim 3 in which the sample receiving cavity has a volume of between about 0.6 μ

l and about 1.0 μ

l.

5. The method of claim 1 which includes obtaining a readout of the concentration of the analyte within about 6 seconds after said detecting.

6. The method of claim 5 which includes obtaining a readout of the concentration of the analyte between about 2 seconds and about 6 seconds after said detecting.

7. The method of claim 6 which includes obtaining a readout of the concentration of the analyte between about 2 seconds and about 5 seconds after said detecting.

8. The method of claim 7 which includes obtaining a readout of the concentration of the analyte within about 5 seconds after said detecting.

9. The method of claim 1 in which said controlling comprises applying a DC voltage of 100-500 mV across the working and counter electrodes, said obtaining comprising measuring the current received from the working electrode and determining the concentration of the analyte from the measured current.

10. The method of claim 9 in which said applying a voltage comprises applying a voltage of about 200 mV to about 400 mV.

11. The method of claim 1 in which said obtaining comprises measuring the current received from the working electrode and determining the concentration of the analyte from the current within ten seconds of said detecting.

12. The method of claim 1 in which the sample receiving cavity has a height of about 25 to about 200 μ

m.

13. The method of claim 1 in which the reagent layer is present as a coating on both the working and counter electrodes.

14. The method of claim 1 in which the analyte is glucose.