Biosensor Systems for Determining Analyte Concentration Based on Complex Index Functions

• US 20140209460A1
• Filed: 04/01/2014
• Published: 07/31/2014
• Est. Priority Date: 12/08/2008
• Status: Active Grant

• Current Assignee: Ascensia Diabetes Care Holdings AG (PHC Holdings Corporation)
• Original Assignee: Bayer Healthcare LLC (Bayer AG)
• Inventors: Wu, Huan-Ping, Jung, Sung-Kwon
• Granted Patent: US 10,656,113 B2
• Time in Patent Office: Days
• US Class Current: 204/403.14
• 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 27/416 Systems G01N27/27 takes precedence

Abstract

A biosensor system determines analyte concentration from an output signal generated from a light-identifiable species or a redox reaction of the analyte. The biosensor system adjusts a correlation for determining analyte concentrations from output signals or determined analyte concentrations with one or more complex index function extracted from the output signals or from other sources. The complex index functions determine at least one slope deviation value, ΔS, or normalized slope deviation from one or more error parameters. The slope-adjusted correlation between analyte concentrations and output signals may be used to determine analyte concentrations having improved accuracy and/or precision from output signals including components attributable to bias.

Claims

1. A biosensor system, for determining an analyte concentration in a sample, comprising:

a test sensor having a sample interface adjacent to a reservoir formed by the strip, wherein the test sensor is capable of generating at least one output signal responsive to the concentration of the analyte in the sample; and

a measurement device having a processor connected to a sensor interface, the sensor interface having electrical communication with the sample interface, and the processor having electrical communication with a storage medium,

wherein the processor is capable of determining at least one output signal value from the output signal received from the sensor interface, wherein the at least one output signal value is responsive to the concentration of the analyte in the sample,

wherein the processor is capable of determining at least one Δ

S value from at least a complex index function stored in the storage medium,

wherein the at least one Δ

S value represents a slope deviation of a correlation between analyte concentration and the at least one output signal,

wherein the weighing coefficients are numerical values other than one or zero,

wherein the complex index function includes at least two terms, wherein each of the at least two terms is modified by a weighing coefficient, wherein at least one of the at least two terms and the weighing coefficients is responsive to a bias between a correlation of analyte concentrations and the at least one output signal, wherein the complex index function is responsive to at least one error parameter, and

wherein the processor is capable of determining the analyte concentration in the sample from the output signal value and a slope compensation equation stored in the storage medium, wherein the slope compensation equation adjusts a slope of at least one reference correlation present in the storage medium with the at least one determined Δ

S value.

2. The system of claim 1, wherein the measurement device is portable.

3. The system of claim 1, the test sensor arranged and configured to have a substantially linear relationship between a percent bias in an analyte concentration determined from the biosensor system and the at least one Δ

S value.

4. The system of claim 3, wherein the percent bias ((Δ

A/Aref)*100%) of the determined analyte concentration is in a substantially linear relationship with the at least one Δ

S value, wherein Δ

A represents the difference between the corrected analyte concentration A_corr and a reference analyte concentration A_ref.

5. The system of claim 1, wherein the storage medium stores at least one pre-determined reference correlation.

6. The system of claim 1, wherein the processor is further capable of determining the at least one Δ

S value from a predictor function, the predictor function including the complex index function and one or more constants.

7. The system of claim 1, wherein the complex index further comprises at least one constant that is not equal to zero.

8. The system of claim 1, wherein one of the at least two terms includes a raw analyte concentration value of the sample.

9. The system of claim 1, wherein one of the at least two terms includes a temperature.

10. The system of claim 1, wherein one of the at least two terms includes an error parameter responsive to the % Hct of the sample.

11. The system of claim 1, wherein at least one other term includes the at least one error parameter, the at least one error parameter independently selected from intermediate output signal values and values external to the output signal.

12. The system of claim 11, wherein the error parameter is responsive to error contributors causing an alteration of the at least one output signal value.

13. The system of claim 11, wherein the error parameter is independently responsive to different error contributors and has an R² correlation with Δ

S_cal of at least 0.3, wherein the Δ

S_cal is represented as follows;

14. The system of claim 1, wherein the at least one Δ

S value determined by the processor from the complex index function has an R² correlation with Δ

S_cal of at least 0.6, wherein the Δ

S_cal is represented as follows;

15. The system of claim 1, wherein the processor is further capable of determining analyte concentrations from multiple samples and the complex index function provides the analyte concentrations determined for the multiple samples a standard deviation value of less than 5 for the combined biases of the multiple samples.

16. The system of claim 15, wherein the analyte concentrations of the multiple samples determined by the processor fall within a ±

10% combined bias limit.

17. The system of claim 15, wherein the analyte concentrations of the multiple samples determined by the processor fall within a ±

8% combined bias limit.

18. The system of claim 15, wherein the analyte concentrations of the multiple samples determined by the processor fall within a ±

5% combined bias limit.

19. The system of claim 1, wherein the processor is further capable of normalizing the at least one Δ

S value, wherein the normalizing is in response to a slope of a reference correlation equation or in response to a normalized slope function.

20. The system of claim 1, the at least two terms selected by at least one exclusion test.

21. The system of claim 1, the at least two terms selected by at least one exclusion test, the at least one exclusion test comprising:

selecting a plurality of terms for potential inclusion in the complex index function;

determining exclusion values for each selected term;

applying at least one exclusion test to the exclusion values to identify one or more terms to exclude from the complex index function, and

excluding at least one term identified for exclusion from the complex index function.

22. The system of claim 1, wherein the slope compensation equation stored in the storage medium is represented as follows:

23. The system of claim 1, the test sensor including electrical conductors connected to a working electrode and a counter electrode.

24. The system of claim 23, the test sensor including conductors providing functionality not provided by the electrodes.

25. The system of claim 23, the working electrode including an enzyme and a mediator.