Complex Index Functions

• US 20110297554A1
• Filed: 06/06/2011
• Published: 12/08/2011
• 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 8,744,776 B2
• Time in Patent Office: Days
• US Class Current: 205/789
• 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 method for determining an analyte concentration in a sample, comprising:

generating at least one output signal value responsive to the concentration of the analyte in the sample;

determining at least one Δ

S value from at least a complex index function, the complex index function including at least two terms, where each of the at least two terms is modified by a weighing coefficient;

compensating the at least one output signal value with at least one reference correlation and the at least one Δ

S value; and

determining the analyte concentration in the sample from the at least one output signal value.

2. The method of claim 1, where percent bias in the determined analyte concentration is in a substantially linear relationship with Δ

S and the compensating is with an equation relating the percent bias in the determined analyte concentration to current.

3. The method of claim 1, where the at least one reference correlation is pre-determined with a reference instrument.

4. The method of claim 1, where the compensating is represented as follows:

5. The method of claim 1, where the complex index function further comprises at least one constant that is not equal to zero.

6. The method of claim 1, where one of the at least two terms includes a raw analyte concentration value of the sample.

7. The method of claim 1, where one of the at least two terms includes a temperature.

8. The method of claim 1, where one of the at least two terms includes an error parameter responsive to the % Hct of the sample.

9. The method of claim 1, where each of the at least two terms includes an error parameter, the error parameter independently selected from intermediate output signal values and values external to the output signal.

10. The method of claim 9, where the error parameter is responsive to error contributors causing an alteration of the at least one output signal value.

11. The method of claim 9, where the error parameter is independently responsive to different error contributors and has an R² correlation with Δ

S_cal of at least 0.3.

12. The method of claim 1, where the at least one Δ

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

S_cal of at least 0.6.

13. The method of claim 1, where the determining the analyte concentration in the sample further comprises 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.

14. The method of claim 13, where the determined analyte concentrations of the multiple samples fall within a ±

10% combined bias limit.

15. The method of claim 13, where the determined analyte concentrations of the multiple samples fall within a ±

8% combined bias limit.

16. The method of claim 13, where the determined analyte concentrations of the multiple samples fall within a ±

5% combined bias limit.

17. The method of claim 1, further comprising:

a second complex index function, where different error parameters are transformed by the complex index function and the second complex index function to provide at least two Δ

S values;

or

an index function, where different error parameters are transformed by the complex index function and the index function to provide at least two Δ

S values.

18. The method of claim 1, further comprising normalizing the at least one Δ

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

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

20. 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; 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,

where the processor determines an output signal value responsive to the concentration of the analyte in the sample from the sensor interface,

where the processor determines at least one Δ

S value from at least a complex index function, the complex index function including at least two terms, where each of the at least two terms is modified by a weighing coefficient, and

where the processor compensates the output signal value with the at least one Δ

S value and at least one reference correlation present in the storage medium.

21-38. -38. (canceled)