Residual Compensation Including Underfill Error

• US 20110231105A1
• Filed: 03/22/2011
• Published: 09/22/2011
• Est. Priority Date: 03/22/2010
• Status: Active Grant

• Current Assignee: Ascensia Diabetes Care Holdings AG (PHC Holdings Corporation)
• Original Assignee: Bayer Healthcare LLC (Bayer AG)
• Inventors: Wu, Huan-Ping, Maurer, Eric, Harrison, Bern
• Granted Patent: US 10,591,436 B2
• Time in Patent Office: Days
• US Class Current: 702/19
• CPC Class Codes: G01N 27/3274 Corrective measures, e.g. error detection, compensation for temperature or hematocrit, calibration coding of calibration information G01N33/48771

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 compensates at least 50% of the total error in the output signal with a primary function and compensates a portion of the remaining error with a residual function. The amount of error compensation provided by the primary and residual functions may be adjusted with a weighing coefficient. The compensation method including a primary function and a residual function may be used to determine analyte concentrations having improved accuracy from output signals including components attributable to error.

Claims

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

generating an output signal responsive to a concentration of an analyte in a sample and an input signal;

determining a compensated output signal from the output signal in response to a primary function and a first residual function; and

determining the analyte concentration in the sample from the compensated output signal.

2. The method of claim 1, where the primary function includes an index function, where the index function is a slope-based function.

3. The method of claim 1, where the primary function includes a complex index function, the complex index function including

at least one term having an hematocrit error parameter, and

at least one term having a temperature error parameter.

4. The method of claim 3, where the complex index function includes a first term and a second term, where the first and the second terms are each modified by a complex index function term weighing coefficient, the first and the second terms each include an error parameter, and the error parameters are independently selected from intermediate output signal values and values external to the output signal.

5. The method of claim 1, further comprising:

converting the output signal with a conversion function including at least one reference correlation prior to determining the compensated output signal.

6. The method of claim 5, further comprising determining the at least one reference correlation with a reference instrument in a controlled environment prior to determining the analyte concentration in the sample

7. The method of claim 1, further comprising adjusting a compensation provided by the first residual function with a first weighing coefficient, where the first weighing coefficient is responsive to a compensation provided by the primary function.

8. The method of claim 7, further comprising:

determining the compensated output signal from the output signal in response to a second residual function.

9. The method of claim 8, further comprising:

adjusting a compensation provided by the second residual function with a second weighing coefficient, where the second weighing coefficient is responsive to the compensation provided by the first residual function.

10. The method of claim 1, where the primary function compensates at least 50% of the total error in the output signal.

11. The method of claim 1, where the primary function is determined from at least one controlled environment test case prior to determining the analyte concentration in the sample.

12. The method of claim 1, where the first residual function substantially compensates errors not compensated by the primary function.

13. The method of claim 1, where the first residual function compensates at least 5% of the total error in the output signal.

14. The method of claim 1, where the first residual function compensates error arising substantially from operating condition errors.

15. The method of claim 14, where the first residual function is determined from at least one self-testing test case prior to determining the analyte concentration in the sample.

16. The method of claim 1, where the first residual function is determined prior to determining the analyte concentration in the sample by a residual function determination method.

17. The method of claim 16, where the residual function determination method comprises:

selecting multiple error parameters as potential terms in the first residual function;

determining a first exclusion value for the potential terms;

applying an exclusion test responsive to the first exclusion value for the potential terms;

identifying one or more of the potential terms for exclusion from the first residual function; and

excluding one or more identified potential terms from the first residual function.

18. The method of claim 1, further comprising:

determining if a test sensor is filled more than once with the sample before the output signal is generated; and

determining the compensated output signal from a different first residual function if the test sensor is filled more than once.

19. The method of claim 1, where the sample is a whole blood sample and the analyte is glucose, and where the determining the analyte concentration in the sample from the compensated output signal reduces the slope of a correlation plot representing hematocrit sensitivity in whole blood to ±

0.4 or less when the whole blood sample has a hematocrit level from about 30% to about 55%.

20. The method of claim 1, where the analyte concentration is determined from at least a forty sample self-testing test case, where the test case has a measurement performance of at least one of

at least 85% of the determined analyte concentrations are within a ±

10% percent bias limit,

at least 95% of the determined analyte concentrations are within a ±

8% percent bias limit, and

at least 60% of the determined analyte concentrations are within a ±

5% percent bias limit.

21. The method of claim 1, where the analyte concentration is determined from at least a 5,000 sample test case, where the test case is at least one of a self-testing test case and a health care professional test case, where the test case uses test sensors from between two and 45 test sensor lots, where the test case has a measurement performance of at least one of

the determined analyte concentrations have an average percent bias standard deviation value of less than five,

at least 90% of the determined analyte concentrations are within a ±

10% percent bias, and

the determined analyte concentrations have a mean percent bias spread within about ±

12%.

22. The method of claim 1, where the analyte concentration lacks at least 60% of the total error of the output signal.

23. The method claim 1, where a mean percent bias of the analyte concentrations determined from the compensated output signal from different lots of test sensors is at least 47% less than a mean percent bias determined from the output signal for analyte concentrations determined from the different lots of test sensors.

24. The method of claim 1, further comprising reducing to ±

5% or less the difference between analyte concentrations determined from test sensors stored for four weeks at −

20°

C. and analyte concentrations determined from test sensors stored for four weeks at 50°

C.

25. The method of claim 18, where 90% or more of the determined analyte concentrations are within a ±

10% percent bias limit when the test sensors are filled more than once with the sample before the output signal is generated.

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

a test sensor having a sample interface in electrical communication with a reservoir formed by the test sensor; and

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

where the processor instructs the signal generator to apply an electrical input signal to the sensor interface,

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

where the processor compensates at least 50% of the total error in the output signal with a primary function,

where the processor compensates at least 5% of the remaining error in the output signal with a first residual function,

where the processor determines a compensated output signal, and

where the processor determines an analyte concentration in a sample from the compensated output signal.

27-39. -39. (canceled)

40. A method for determining an analyte concentration in a sample, comprising:

generating an output signal responsive to a concentration of an analyte in a sample and an input signal;

compensating the output signal with a primary function and a first residual function; and

determining the analyte concentration in the sample from a compensated output signal.

41-42. -42. (canceled)

43. A method of determining a desired residual function for compensating an analyte concentration of a sample, comprising:

generating an output signal responsive to a concentration of an analyte in a sample;

selecting multiple error parameters as potential terms in a residual function, the error parameters describing at least a portion of the total error in the output signal;

determining a first exclusion value for the potential terms;

applying an exclusion test responsive to the first exclusion value for the potential terms;

identifying one or more of the potential terms for exclusion from the residual function;

excluding one or more identified potential terms from the residual function; and

determining a desired residual function.