Method and apparatus for correcting ambient temperature effect in biosensors

• US 6,391,645 B1
• Filed: 05/12/1997
• Issued: 05/21/2002
• Est. Priority Date: 05/12/1997
• Status: Expired due to Term

• Current Assignee: Ascensia Diabetes Care Holdings AG (PHC Holdings Corporation)
• Original Assignee: Bayer Corporation (Bayer AG)
• Inventors: Huang, Dijia, Tudor, Brenda L., Yip, Kin-Fai
• Primary Examiner(s): SNAY, JEFFREY R
• Application Number:
  US08/854,440
• Time in Patent Office: 1,835 Days
• Field of Search: 422/82.02, 436/95, 436/151, 436/152, 435/14, 435/25, 435/287.1, 435/817, 205/777.5
• US Class Current: 436/95
• CPC Class Codes: C12Q 1/006 for glucose
• 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: Y10T 436/144444 Glucose

Abstract

A method and apparatus are provided for correcting ambient temperature effect in biosensors. An ambient temperature value is measured. A sample is applied to the biosensors, then a current generated in the test sample is measured. An observed analyte concentration value is calculated from the current through a standard response curve. The observed analyte concentration is then modified utilizing the measured ambient temperature value to thereby increase the accuracy of the analyte determination. The analyte concentration value can be calculated by solving the following equation: $G_2=\frac{G_1-\left(T_2^2-{24}^2\right)*\mathrm{I2}-\left(T_2-24\right)*\mathrm{I1}}{\left(T_2^2-{24}^2\right)*\mathrm{S2}+\left(T_2-24\right)*\mathrm{S1}+1}$

where G₁ is said observed analyte concentration value, T₂ is said measured ambient temperature value and I1, I2, S1, and S2 are predetermined parameters.

Claims

1. A method for correcting ambient temperature effect in biosensors comprising the steps of:

measuring an ambient temperature value;

applying a sample to the biosensors and measuring a current generated in the test sample;

calculating an analyte concentration value utilizing said measured ambient temperature value to thereby increase the accuracy of the analyte determination; and

said step of calculating said analyte concentration value includes the step of converting said measured current to an observed analyte concentration value and calculating a corrected analyte concentration value utilizing the equation;

$G_2=\frac{G_1-\left(T_2^2-{24}^2\right)*\mathrm{I2}-\left(T_2-24\right)*\mathrm{I1}}{\left(T_2^2-{24}^2\right)*\mathrm{S2}+\left(T_2-24\right)*\mathrm{S1}+1}$

 

where G₁ is said observed analyte concentration value, T₂ is said measured ambient temperature value and I1, I2, S1, and S2 are set values and are experimentally determined coefficients.

2. A method for correcting ambient temperature effect in biosensors as recited in claim 1 wherein I1, I2, S1, and S2 are experimentally determined coefficients by sequentially providing a sample to a plurality of concentration values and measuring a resulting current response for each of the plurality of concentration values for each of a plurality of temperature values;

generating plots of said observed analyte concentration values and using the following equations;

3. A method for correcting ambient temperature effect in biosensors as recited in claim 1 wherein the analyte is glucose.

4. Apparatus for correcting ambient temperature effect in biosensors comprising:

means for measuring an ambient temperature value;

means responsive to an applied sample to the biosensors, for measuring a current generated in the test sample;

means for calculating an analyte concentration value utilizing said measured ambient temperature value to thereby increase the accuracy of the analyte determination; and

wherein said means for calculating said analyte concentration value includes means for converting said measured current to an observed analyte concentration value and for calculating a corrected analyte concentration value utilizing the equation;

$G_2=\frac{G_1-\left(T_2^2-{24}^2\right)*\mathrm{I2}-\left(T_2-24\right)*\mathrm{I1}}{\left(T_2^2-{24}^2\right)*\mathrm{S2}+\left(T_2-24\right)*\mathrm{S1}+1}$

 

where G₁ is said observed analyte concentration value, T₂ is said measured ambient temperature value and I1, I2, S1, and S2 are set values and are experimentally determined coefficients.

5. Apparatus for correcting ambient temperature effect in biosensors as recited in claim 4 includes processor means for performing a predefined test sequence;

and,wherein said means for measuring said ambient temperature value includes a thermistor coupled to said processor means.

6. Apparatus for correcting ambient temperature effect in biosensors as recited in claim 4 wherein I1, I2, S1, and S2 are experimentally determined coefficients by sequentially providing a sample to a plurality of concentration values and measuring a resulting current response for each of the plurality of concentration values for each of a plurality of temperature values;

generating plots of said observed analyte concentration values and using the following equations;

7. Apparatus for correcting ambient temperature effect in biosensors as recited in claim 4 wherein the analyte is glucose.

8. Apparatus for correcting ambient temperature effect in biosensors as recited in claim 4 wherein said means responsive to said applied sample to the biosensors, for measuring said current generated in the test sample includes processor means coupled to the biosensors for receiving a signal representing said current generated in the test sample.

9. Apparatus for correcting ambient temperature effect in biosensors as recited in claim 4 wherein said means for calculating said analyte concentration value includes processor means coupled to said ambient temperature measuring means and said current measuring means and including means for solving said equation utilizing said measured values and predetermined coefficient values.

10. A biosensor comprising:

biosensors means for receiving a user sample;

processor means responsive to said user sample receiving means, for measuring a current generated in the test sample;

means for measuring an ambient temperature value; and

means for calculating an analyte concentration value utilizing said measured ambient temperature value to thereby increase the accuracy of the analyte determination; and

wherein said processor means includes means for converting said measured current to an observed analyte concentration value and for calculating a corrected analyte concentration value utilizing the equation;

$G_2=\frac{G_1-\left(T_2^2-{24}^2\right)*\mathrm{I2}-\left(T_2-24\right)*\mathrm{I1}}{\left(T_2^2-{24}^2\right)*\mathrm{S2}+\left(T_2-24\right)*\mathrm{S1}+1}$

 

where G₁ is said observed analyte concentration value, T₂ is said measured ambient temperature value and I1, I2, S1, and S2 are set values and are experimentally determined coefficients.

11. A biosensor as recited in claim 10 wherein I1, I2, S1, and S2 are experimentally determined coefficients by sequentially providing a sample to a plurality of concentration values and measuring a resulting current response for each of the plurality of concentration values for each of a plurality of temperature values, generating plots of said observed analyte concentration values and using the following equations:

12. A biosensor as recited in claim 10 wherein said means for measuring said ambient temperature value include a thermistor coupled to said processor means.