SYSTEMS AND METHODS FOR IMPROVED STABILITY OF ELECTROCHEMICAL SENSORS

• US 20120080326A1
• Filed: 09/30/2010
• Published: 04/05/2012
• Est. Priority Date: 09/30/2010
• Status: Active Grant

• Current Assignee: LifeScan IP Holdings, LLC
• Original Assignee: Cilag Gmbh International (Johnson & Johnson)
• Inventors: Chatelier, Ronald C., Hodges, Alastair M.
• Granted Patent: US 8,932,445 B2
• Time in Patent Office: Days
• US Class Current: 205/782
• CPC Class Codes: C12Q 1/001 Enzyme electrodes
• CPC Class Codes: C12Q 1/54 involving glucose or galactose
• 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 27/3274 Corrective measures, e.g. error detection, compensation for temperature or hematocrit, calibration coding of calibration information G01N33/48771
• CPC Class Codes: G01N 33/5438 Electrodes

Abstract

Methods for determining a concentration of an analyte in a sample, and the devices and systems used in conjunction with the same, are provided herein. In one exemplary embodiment of a method for determining a concentration of an analyte in a sample, a sample including an analyte is provided in a sample analyzing device having a working and a counter electrode. An electric potential is applied between the electrodes and a measurement of a parameter correlating to changes in a physical property of the sample analyzing device is calculated. A concentration of the analyte in view of the parameter correlating to a change in the physical property can then be determined Systems and devices that take advantage of the parameter correlating to changes in a physical property to make analyte concentration determinations are also provided.

Claims

1. A method for determining a concentration of an analyte in a sample, the method comprising:

introducing a sample including an analyte into an electrochemical cell of a sample analyzing device to cause a transformation of the analyte, the electrochemical cell having a first electrode and a second electrode;

determining a measurement of a parameter correlating to a physical property of the electrochemical cell;

calculating a correction factor, wherein said correction factor is in view of at least said parameter; and

determining a concentration of the analyte in view of the correction factor.

2. The method of claim 1, wherein said parameter comprises a measured capacitance of the electrochemical cell.

3. The method of claim 2, wherein determining said measured capacitance of the electrochemical cell comprises:

applying a first test voltage between the first electrode and the second electrode, the first test voltage having an AC voltage component and a DC voltage component, the AC voltage component being applied at a predetermined amount of time after the application of the first test voltage, the DC voltage component having a magnitude sufficient to cause a limiting test current at the second electrode, the second electrode not having a reagent layer coating; and

processing a portion of the test currents, resulting from the AC voltage component, into a capacitance value.

4. The method of claim 1, wherein said physical property is related to at least one of an age of the electrochemical cell and a storage condition of the electrochemical cell.

5. The method of claim 4, wherein said storage condition comprises a storage temperature and a storage time.

6. The method of claim 1, wherein the sample analyzing device comprises a glucose sensor.

7. The method of claim 1, wherein the sample analyzing device comprises an immunosensor.

8. The method of claim 1, wherein the sample comprises blood.

9. The method of claim 8, wherein the blood comprises whole blood.

10. An electrochemical system, comprising:

an electrochemical cell having a first electrode and a second electrode;

a meter including a control unit connected to the electrochemical cell so that the control unit applies a potential between the first electrode and the second electrode of the electrochemical cell and

the control unit determines a measurement of a parameter correlating to a physical property of the electrochemical cell and uses said measurement to calculate a corrected concentration of the analyte in the sample.

11. The electrochemical system of claim 10, wherein said parameter comprises a measured capacitance of the electrochemical cell.

12. The electrochemical system of claim 10, wherein said physical property is related to at least one of an age of the electrochemical cell and a storage condition of the electrochemical cell.

13. The method of claim 12, wherein said storage condition comprises a storage temperature and a storage time.

14. The electrochemical system of claim 10, wherein the sample comprises blood.

15. The electrochemical system of claim 14, wherein the blood comprises whole blood.

16. A method for measuring a corrected analyte concentration, the method comprising:

applying a sample containing an analyte to a test strip;

applying to the sample a first test voltage for a first time interval between a first electrode and a second electrode sufficient to oxidize a reduced mediator at the second electrode;

following the application of the first test voltage, applying to the sample a second test voltage for a second time interval between the first electrode and the second electrode sufficient to oxidize the reduced mediator at the first electrode

calculating a first analyte concentration in the sample based on test current values during the first time interval and the second time interval;

determining a capacitance of the test strip; and

calculating a capacitance corrected analyte concentration based on the first glucose concentration and the capacitance.

17. The method of claim 16, wherein the step of calculating the capacitance corrected analyte concentration comprises:

calculating a correction factor based on the capacitance and the first analyte concentration, wherein the capacitance corrected analyte concentration is calculated based on the first analyte concentration and the correction factor.

18. The method of claim 16, wherein determining a capacitance of the test strip comprises:

applying a first test voltage between the first electrode and the second electrode, the first test voltage having an AC voltage component and a DC voltage component, the AC voltage component being applied at a predetermined amount of time after the application of the first test voltage, the DC voltage component having a magnitude sufficient to cause a limiting test current at the second electrode, the second electrode not having a reagent layer coating; and

processing a portion of the test currents, resulting from the AC voltage component, into a capacitance value.

19. The method of claim 16, wherein the capacitance corrected analyte concentration is calculated when the capacitance is less than a first capacitance threshold and the first analyte concentration is greater than a first analyte concentration threshold.

20. The method of claim 16, wherein the step of calculating the capacitance corrected analyte concentration further comprises:

dividing the correction factor by one hundred and adding one to give an intermediate term; and

multiplying the intermediate term by the first analyte concentration to give a capacitance corrected analyte concentration.

21. The method of claim 16 further comprising:

determining if the correction factor is greater than a correction factor threshold value, then setting the correction factor to the correction factor threshold value.

22. The method of claim 16, wherein the correction factor is about zero when the capacitance is about equal to a predetermined ideal capacitance of the test strip.

23. The method of claim 16, wherein the analyte comprises glucose.

24. An electrochemical system, comprising:

(a) a test strip including electrical contacts configure to mate with a test meter and an electrochemical cell comprising;

(i) a first electrode and a second electrode in a spaced apart relationship; and

(ii) a reagent; and

(b) a test meter including a processor adapted to receive current data from the test strip upon application of voltages to the test strip, and further adapted to determine a capacitance corrected glucose concentration based on a calculated glucose concentration and a measured capacitance.

25. The electrochemical system of claim 24, wherein said test meter includes data storage containing a glucose concentration threshold and a capacitance threshold.

26. The electrochemical system of claim 24, wherein said processor determines the capacitance corrected glucose concentration value when the measured capacitance is less than the capacitance threshold and the calculated glucose concentration is greater than the glucose concentration threshold.

27. The electrochemical system of claim 24, wherein the measured capacitance correlates with a physical property of the test strip relating to at least one of an age of the test strip and a storage condition of the test strip.

28. The method of claim 27, wherein said storage condition comprises a storage temperature and a storage time.