Methods for determining an analyte concentration using signal processing algorithms

• US 8,460,537 B2
• Filed: 09/03/2009
• Issued: 06/11/2013
• Est. Priority Date: 10/05/2006
• Status: Expired due to Fees

• Current Assignee: Cilag Gmbh International (Johnson & Johnson)
• Original Assignee: LifeScan Scotland Limited (Johnson & Johnson)
• Inventors: Blythe, Stephen Patrick, Alvarez-Icaza, Manuel, Day, Emma Vanessa Jayne, Day, Richard Michael, Leach, Christopher Philip, Cardosi, Marco F, Mills, Leanne
• Primary Examiner(s): Van, Luan
• Assistant Examiner(s): RUFO, LOUIS J
• Application Number:
  US12/553,976
• Publication Number:
  US 20110005941A1
• Time in Patent Office: 1,377 Days
• Field of Search: 205/775, 205/792, 204/403.14, 204/403.04, 702/25
• US Class Current: 205/775
• CPC Class Codes: G01N 27/3273 Devices therefor, e.g. test element readers, circuitry details not specific to biochemical electrodes G01N33/4875

Abstract

A method for determining an analyte concentration in blood is described that reduces the effects of hematocrit using a test strip attached to a test meter. The test strip includes a working electrode and a reference electrode. The test meter applies a test voltage between the working electrode and the reference electrode. After a user applies a blood sample containing an analyte onto the test strip, the test meter measures a plurality of test currents for a test time interval.

Claims

1. A method for determining an analyte concentration using a test strip having a working electrode and a reference electrode, the method comprising:

applying a test voltage between the working electrode and the reference electrode;

measuring a plurality of test currents with the test meter when a blood sample containing the analyte is applied to the test strip;

calculating an analyte correlation value (Y) using an equation which is

2. The method of claim 1, wherein a duration of the first pre-determined time interval, the second pre-determined time interval, and the third pre-determined time interval are calculated by minimizing the effect of hematocrit.

3. The method of claim 1, wherein a sum of a duration of the first pre-determined time interval and of the third pre-determined time interval does not equal the second pre-determined time interval.

4. The method of claim 1, wherein a sum of a duration of the first pre-determined time interval and of the third pre-determined time interval equals the second pre-determined time interval.

5. The method of claim 1, wherein the analyte correlation value (Y) is calculated during the test time interval, whereby a microprocessor in the test meter can calculate the analyte concentration faster than if the test meter calculates the analyte correlation value (Y) after the test time interval.

6. The method of claim 1 further comprising the step of:

determining a maximum peak time from the plurality of test current;

determining an ending point of a first pre-determined time interval by multiplying the maximum peak time times a calibration factor.

7. The method of claim 6, wherein the calibration factor ranges from about 0.5 to about less than one.

8. The method of claim 1, wherein a reagent layer is disposed over the working electrode, the reagent layer comprising:

an enzyme;

a ruthenium hexamine mediator; and

a buffer for dissolving the enzyme and the ruthenium hexamine mediator;

wherein the ruthenium hexamine has a concentration range from about 15% to about 20%(weight/volume).

9. The method of claim 8, wherein the enzyme is a material selected from the group consisting of glucose oxidase and glucose dehydrogenase.

10. The method of claim 8, wherein the buffer is a chemical selected from the group consisting of phosphate, citrate, and citraconate.

11. The method of claim 8, wherein the buffer is phosphate and has a pH of about 7.

12. The method of claim 8, wherein the formulation further comprises a filler having hydrophilic and hydrophobic domains.

13. The method of claim 8, wherein the filler comprises silca modified by surface treatment with methyl dichorosilane.

14. The method of claim 8, wherein the formulation is printed on the working electrode via a screen that secures a plurality of interwoven threads, the plurality of interwoven threads defining a plurality of open rectangular spaces for allowing the formulation to pass therethrough, the plurality of interwoven threads having a thread spacing and a thread diameter, wherein the thread spacing ranges from about 90 threads per centimeter to about 120 threads per centimeter and the thread diameter may range from about 30 microns to about 50 microns.

15. The method of claim 1, wherein the working electrode comprises microelectrode array.

16. The method of claim 1, wherein the test strip further comprises an integrated lance.