Methods for measuring physiological fluids

• US 20070084734A1
• Filed: 10/17/2005
• Published: 04/19/2007
• Est. Priority Date: 10/17/2005
• Status: Active Grant

• Current Assignee: Cilag Gmbh International (Johnson & Johnson)
• Original Assignee: Lifescan Incorporated (Duv Holding Corporation)
• Inventors: Roberts, Neil, Smeaton, Gary
• Granted Patent: US 8,066,866 B2
• Time in Patent Office: Days
• US Class Current: 205/792
• 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

Electrochemical measurement techniques for measuring the concentration of an analyte in a physiological fluid sample are described. More particularly, the present invention relates to techniques for distinguishing a signal caused by an extraneous event from a desired information providing signal such as one indicative of a measurement error.

Claims

1. A method of electrochemically analyzing a physiological fluid sample to determine the concentration of an analyte present in the physiological fluid sample, the method comprising the steps of:

providing a test device comprising a test fluid application portion having at least a pair of electrodes and a reagent;

providing a predetermined potential across the at least a pair of electrodes;

detecting a current at the at least a pair of electrodes equal to or above a threshold value and subsequently monitoring the magnitude of the current over a first time period; and

performing one of the following;

1) if the magnitude of the current remains above a predetermined value over the first time period, then using the magnitude of the current at the end of a second time period as a test reading indicative of the concentration of an analyte in a physiological fluid present in the test fluid application area of the test device wherein the first time period comprises an initial portion of the second time period; and

2) if the magnitude of the current is equal to or below the predetermined value anytime during the first time period, then repeating the step of detecting a current and the step of performing one of the following.

2. The method of claim 1, further comprising providing a physiological fluid sample at the test fluid application portion of the test device.

3. The method of claim 2, wherein the step of detecting a current comprises detecting a current generated by a reaction between the provided physiological fluid sample and the reagent of the test device.

4. The method of claim 1, wherein the step of detecting a current comprises detecting a current generated by an extraneous event.

5. The method of claim 4, wherein the extraneous event comprises electrostatic discharge.

6. The method of claim 1, wherein the threshold value of the detected current is indicative of the presence of a physiological fluid present in the test fluid application area of the test device.

7. The method of claim 1, wherein step 2) comprises waiting until the end of the first time period before repeating the step of detecting a current and the step of performing one of the following.

8. The method of claim 1, comprising using the magnitude of the current at the end of at least one additional time period as at least one additional test reading indicative of the concentration of an analyte in a physiological fluid present in the test fluid application area of the test device.

9. The method of claim 8, comprising using the test reading indicative of the concentration of an analyte in a physiological fluid and the at least one additional test reading indicative of the concentration of an analyte in a physiological fluid to determine the concentration of the analyte in the physiological fluid.

10. The method of claim 1, wherein the duration of the first time period is greater than the time needed for a current spike from a predetermined extraneous event to decay below the threshold value and less than the second time period.

11. The method of claim 1, wherein the duration of the first time period is less than about 500 milliseconds.

12. The method of claim 1, wherein the duration of the first time period is less than about 100 milliseconds.

13. A method of preventing electrostatic discharge from interfering with an electrochemical measurement of the concentration of an analyte in a physiological fluid sample, the method comprising the steps of:

providing a test device comprising a test fluid application portion having at least a pair of electrodes and a reagent;

providing a predetermined potential across the at least a pair of electrodes;

measuring a current at the at least a pair of electrodes and using the magnitude of the current at the end of a first predetermined time period as a test reading indicative of the concentration of an analyte in a physiological fluid present in the test fluid application area of the test device if the magnitude of the current remains above a threshold current value for a second predetermined time period wherein the second time period comprises an initial portion of the first time period.

14. The method of claim 13, wherein the predetermined potential provided across the at least a pair of electrodes is continuously provided over the first time period.

15. The method of claim 14, wherein the predetermined potential provided across the at least a pair of electrodes is constant in magnitude over the first time period.

16. The method of claim 13, wherein the duration of the second time period is greater than the time needed for a current spike from a predetermined extraneous event to decay below the threshold value and less than the first time period.

17. The method of claim 13, wherein the duration of the second time period is less than about 100 milliseconds.

20. The testing system of claim 13, wherein the duration of the second time period is less than about 100 milliseconds.

18. A testing meter for electrochemically measuring the concentration of an analyte in a physiological fluid sample, the testing meter comprising:

a processor;

an electrochemical measurement device that can be electrically connected to a test device comprising a fluid application portion having at least a pair of electrodes and a reagent so that the electrochemical measurement device can provide a potential and measure current flow across the at least a pair of electrodes when a test device is electrically connected to the electrochemical measurement device; and

memory comprising programming that can cause the electrochemical meter, when a test device is electrically connected thereto, to measure a current at the least a pair of electrodes and use the magnitude of the current at the end of a first predetermined time period as a test reading indicative of the concentration of an analyte in a physiological fluid present in the test fluid application area of the test device if the magnitude of the current remains above a threshold current value for a second predetermined time period wherein the second time period comprises an initial portion of the first time period.

19. The testing system of claim 18, wherein the duration of the second time period is greater than the time needed for a current spike from a predetermined extraneous event to decay below the threshold value and less than the first time period.