ELECTROCHEMICAL ANALYTE MEASUREMENT METHOD AND SYSTEM

• US 20130095510A1
• Filed: 03/30/2011
• Published: 04/18/2013
• Est. Priority Date: 03/31/2010
• Status: Active Grant

• Current Assignee: Cilag Gmbh International (Johnson & Johnson)
• Original Assignee: LifeScan Scotland Limited (Johnson & Johnson)
• Inventors: Malecha, Michael, Craggs, Adam
• Granted Patent: US 8,962,270 B2
• Time in Patent Office: Days
• US Class Current: 435/14
• 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 33/49 Blood chemical methods for determining blood cell populations G01N33/5094; chemical analysis of blood groups or blood types G01N33/80
• CPC Class Codes: G16B 99/00 Subject matter not provided for in other groups of this subclass

Abstract

Described and illustrated herein are systems and exemplary methods of operating an analyte measurement system having a meter and a test strip. In one embodiment, the method may be achieved by applying a first test voltage between a reference electrode and a second working electrode and applying a second test voltage between the reference electrode and a first working electrode; measuring a first test current, a second test current, a third test current and a fourth test current at the second working electrode after a blood sample containing an analyte is applied to the test strip; measuring a fifth test current at the first working electrode; estimating a hematocrit-corrected analyte concentration from the first, second, third, fourth and fifth test currents; and annunciating the hematocrit-corrected analyte concentration.

Claims

1. A method for determining a glucose concentration measurable with a system having a test strip and a meter having a test circuit including a microprocessor, the method comprising:

applying, with the test circuit, a first test voltage between a reference electrode and a second working electrode coated with a reagent layer of the test strip and applying a second test voltage between the reference electrode and a first working electrode coated with a reagent layer;

measuring a first test current, a second test current, a third test current and a fourth test current at the second working electrode after a blood sample is applied to the test strip;

measuring a fifth test current at the first working electrode;

determining, with the microprocessor, a glucose concentration based on the first, second, third, fourth and fifth test currents; and

annunciating the glucose concentration.

2. The method of claim 1, in which the reference electrode, the first electrode and the second electrodes are disposed on a single plane.

3. The method of claim 1, in which the first test current is measured from about 0.98 to about 1.00 seconds after initiation of the measuring.

4. The method of claim 1, in which the second current is measured from about 1.98 to about 2.00 seconds after initiation of the measuring.

5. The method of claim 1, in which the third current is measured from about 2.43 to about 2.45 seconds after initiation of the measuring.

6. The method of claim 1, in which the fourth current is measured from about 2.61 to about 2.63 seconds after initiation of the measuring.

7. The method of claim 1, in which the fifth current is measured from about 2.70 to about 2.72 seconds after initiation of the measuring.

8. The method of claim 1, in which the first test current is measured from about 3.37 to about 3.39 seconds after a reaction period of time.

9. The method of claim 1, in which the second current is measured from about 3.46 to about 3.48 seconds after a reaction period of time.

10. The method of claim 1, in which the third current is measured from about 3.54 to about 3.56 seconds after a reaction period of time.

11. The method of claim 1, in which the fourth current is measured from about 4.05 to about 4.07 seconds after a reaction period of time.

12. The method of claim 1, in which the fifth current is measured from about 4.08 to about 4.10 seconds after a reaction period of time.

13. The method of claim 1, in which the glucose concentration comprises a value obtained with an equation of the form:

14. The method of claim 13, in which first tuning parameter is from about 9.9 to about 10.2 and second tuning parameter is from about 10.8 to about 11.2.

15. A method for determining a glucose concentration measurable with a system having a test strip and a meter, the method comprising:

applying a first test voltage between a reference electrode and a second working electrode coated with a reagent layer and applying a second test voltage between a reference electrode and a first working electrode coated with a reagent layer;

measuring a first test current, a second test current, a third test current and a fourth test current at the second working electrode after a blood sample containing glucose is applied to the test strip;

measuring a fifth test current at the first working electrode;

determining the glucose concentration from the first, second, third, fourth and fifth test currents with an equation of the form;

16. The method of claim 15, in which first tuning parameter is from about 9.9 to about 10.2 and second tuning parameter is from about 10.8 to about 11.2.

17. A method for determining a hematocrit-corrected test current measurable with a system having a test strip and a meter, the method comprising:

applying a first test voltage between a reference electrode and a second working electrode coated with a reagent layer and applying a second test voltage between a reference electrode and a first working electrode coated with a reagent layer;

measuring a first test current, a second test current, a third test current and a fourth test current at the second working electrode after a blood sample containing glucose is applied to the test strip;

measuring a fifth test current at the first working electrode; and

determining the hematocrit-corrected test current by determining a ratio of the first test current to the second test current raised to a power term and multiplying the ratio by the fifth test current, where the power term is a function of a first tuning parameter and a second tuning parameter.

18. The method of claim 17, in which first tuning parameter is from about 31 to about 33 and second tuning parameter is from about 53 to about 55;

the first test current comprises a current measured from about 0.9 to about 1.0 seconds after initiation of the measuring;

the second current comprises a current measured from about 1.1 to about 2.0 seconds after initiation of the measuring;

the third current comprises a current measured from about 2.4 to about 2.5 seconds after initiation of the measuring;

the fourth current comprises a current measured from about four 2.61 to about 2.63 seconds after initiation of the measuring;

the fifth current comprises a current measured from about 2.70 to about 2.72 seconds after initiation of the measuring.

19. The method of claim 17, in which no test voltage is applied for a period of time after the deposition of the physiological fluid to provide for a reaction time before application of the test voltage.

20. The method of claim 19, in which the first test current is measured from about 3.37 to about 3.39 seconds after a reaction period of time;

the second current is measured from about 3.46 to about 3.48 seconds after a reaction period of time;

the third current is measured from about 3.54 to about 3.56 seconds after a reaction period of time;

the fourth current is measured from about 4.05 to about 4.07 seconds after a reaction period of time;

the fifth current is measured from about 4.08 to about 4.10 seconds after a reaction period of time.

21. The method of claim 20, in which the reference electrode, the first electrode and the second electrodes are disposed on one plane.

22. An analyte measurement system to measure a glucose concentration in physiological fluid of a user, the system comprising:

a test strip including a substrate having a reference electrode, a first working electrode and a second working electrode coated with a reagent layer having a mediator, the electrodes being connected to corresponding contact pads; and

an analyte meter having a microprocessor and a test circuit in connection with a test strip port that receives the contact pads of the test strip so that the meter is configured to apply a test voltage after deposition of physiological fluid on the electrodes and determine a hematocrit-corrected glucose concentration from measured first, second, third, fourth and fifth test currents at first, second, third, fourth and fifth discrete intervals after application of the test voltage by the meter.

24. The system any one of claims 22 and 23, in which the first test current comprises a current measured from about 0.98 to about 1.00 seconds after initiation of the measuring;

the second current comprises a current measured from about 1.09 to about 2.00 seconds after initiation of the measuring;

the third current comprises a current measured from about 2.43 to about 2.45 seconds after initiation of the measuring;

the fourth current comprises a current measured from about four 2.61 to about 2.63 seconds after initiation of the measuring;

the fifth current comprises a current measured from about 2.70 to about 2.72 seconds after initiation of the measuring.

25. The system of any one of claims 22 and 23, in which the first test current is measured from about 3.37 to about 3.39 seconds after a reaction period of time;

the second current is measured from about 3.46 to about 3.48 seconds after a reaction period of time;

the third current is measured from about 3.54 to about 3.56 seconds after a reaction period of time;

the fourth current is measured from about 4.05 to about 4.07 seconds after a reaction period of time;

the fifth current is measured from about 4.08 to about 4.10 seconds after a reaction period of time.

23. An analyte measurement system to measure a glucose concentration in physiological fluid of a user, the system comprising:

a test strip including a substrate having a reference electrode, a first working electrode and a second working electrode coated with a reagent layer having a mediator, the electrodes being connected to corresponding contact pads; and

an analyte meter having a microprocessor and a test circuit in connection with a test strip port that receives the contact pads of the test strip so that the meter is configured to apply a test voltage after deposition of physiological fluid on the electrodes and determine a hematocrit-corrected glucose concentration from measured first, second, third, fourth and fifth test currents so that at least 97% of plural samples are within an ISO (International Standards Organization) bias criteria of about ±

20%, with at least 85% of the plural samples are within ISO bias criteria of about ±

15%, and at least 69% of the samples are within ISO bias criteria of about ±

10%.