Abnormal Output Detection System For A Biosensor

• US 20090099787A1
• Filed: 10/17/2008
• Published: 04/16/2009
• Est. Priority Date: 05/08/2006
• Status: Active Grant

• Current Assignee: Ascensia Diabetes Care Holdings AG (PHC Holdings Corporation)
• Original Assignee: Bayer Healthcare LLC (Bayer AG)
• Inventors: Carpenter, Scott, Nelson, Christine D., WU, Huan-Ping
• Granted Patent: US 8,234,076 B2
• Time in Patent Office: Days
• US Class Current: 702/19
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/1486 using enzyme electrodes, e.g. with immobilised oxidase
• CPC Class Codes: C12Q 1/001 Enzyme electrodes
• 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: G16B 20/00 ICT specially adapted for functional genomics or proteomics, e.g. genotype-phenotype associations
• CPC Class Codes: G16B 5/00 ICT specially adapted for modelling or simulations in systems biology, e.g. gene-regulatory networks, protein interaction networks or metabolic networks
• CPC Class Codes: G16C 20/10 Analysis or design of chemical reactions, syntheses or processes

Abstract

A biosensor has an abnormal output detection system that determines whether an output signal from the redox reaction of an analyte has a normal or abnormal shape or configuration. The abnormal output detection system improves the accuracy and precision of the biosensor in determining whether an output signal has a shape or configuration that may not provide an accurate and/or precise analysis of a biological fluid. The biosensor generates an output signal in response to the redox reaction of the analyte. The biosensor normalizes the output signal and compares the normalized output signal with one or more control limits. The biosensor may generate an error signal when the normalized output signal is not within the control limits.

Claims

1. A method for detecting abnormal output in a biosensor, comprising:

normalizing an output signal from a redox reaction of analyte in a sample of a biological fluid;

comparing a normalized output signal to at least one control limit; and

generating an error signal when the normalized output signal is not within the at least one control limit.

2. The method of claim 1, further comprising determining a difference between at least one base output value and at least one measured output value of the output signal.

3. The method of claim 2, where the output signal is responsive to a pulsed sequence.

4. The method of claim 2, where the at least one base output value is a measured output value of the output signal.

5. The method of claim 1, further comprising dividing at least one output value in a pulse of the output signal by the first output value in the pulse of the output signal.

6. The method of claim 5, where the output signal is responsive to a gated amperometry electrochemical system.

7. The method of claim 1, further comprising generating the output signal in response to a pulsed sequence.

8. The method of claim 7, where the pulsed sequence comprises at least five pulses.

9. The method of claim 8, where the normalized current value of the fourth pulse, R₄, is represented by the following equation:

10. The method of claim 9, where R₄ is greater than or equal to 0.45, and where R₄ is less than or equal to 0.85.

11. The method of claim 8, where the normalized current value of the fifth pulse, R₅, is represented by the following equation:

12. The method of claim 11, where R₅ is greater than or equal to 0.45, and where R₅ is less than or equal to 0.85.

13. The method of claim 8, where the ratio of the normalized current value of the fourth pulse to the normalized current value of the fifth pulse is represented by the following equation:

14. The method of claim 13, where Ratio is greater than or equal to 0.75, and where Ratio is less than or equal to 1.25.

15. The method of claim 1, further comprising determining the at least one control limit from a statistical analysis of laboratory results.

39. The method of claim 1, further comprising determining the at least one control limit from a statistical analysis of laboratory results.

16. A method for detecting abnormal output in a biosensor, comprising:

generating an output signal in response to a redox reaction of an analyte in a sample of a biological fluid;

measuring the output signal;

normalizing the output signal;

comparing a normalized output signal to at least one control limit; and

generating an error signal when the normalized output signal is not within the at least one control limit.

17. The method of claim 16, further comprising applying an input signal to the sample of the biological fluid.

18. The method of claim 17, where the input signal comprises a pulsed sequence.

19. The method of claim 17, where the input signal is responsive to a gated amperometry electrochemical system.

20. The method of claim 17, where the input signal comprises a polling input signal and an assay input signal.

21. The method of claim 20, where the polling input signal has a polling pulse width of less than about 300 ms, and where the polling input signal has a polling pulse interval of less than about 1 sec.

22. The method of claim 21, where the polling input signal has a polling pulse width in the range of about 0.5 ms through about 75 ms, and where the polling input signal has a polling pulse interval in the range of about 5 ms through about 300 ms.

23. The method of claim 20, where the assay input signal has an assay pulse width of less than about 5 sec, and where the assay input signal has an assay pulse interval of less than about 15 sec.

24. The method of claim 23, where the assay input signal has an assay pulse width in the range of about 0.1 sec through about 3 sec, and where the assay input signal has an assay pulse interval in the range of about 0.2 sec through about 6 sec.

25. The method of claim 20, further comprising:

applying the polling input signal during a polling period, where the polling period is less than about 180 sec; and

applying the assay input signal during an assay period, where the assay period is less than about 180 sec.

26. The method of claim 20, further comprising:

applying the polling input signal during a polling period, where the polling period is in the range of about 0.1 sec through about 10 sec; and

applying the assay input signal during an assay period, where the assay period is in the range of about 1 sec through about 100 sec.

27. The method of claim 20, further comprising:

applying a polling input signal to the sample for about 1.25 sec where the polling input signal has a polling pulse width of about 5-10 ms and a polling pulse interval of about 125 ms; and

applying an assay input signal to the sample for about 7 sec, where the assay input signal has an assay pulse width of about 1 sec and an assay pulse interval of about 1.5 sec.

28. The method of claim 27, where the polling input signal has a potential of about 400 mV, where the assay input signal has a first pulse with a potential of about 400 mV, where the assay input signal has at least one other pulse with a potential of about 200 mV.

29. The method of claim 20, further comprising applying the assay input signal when a polling output signal is greater than or equal to a polling threshold.

30. The method of claim 29, where the polling threshold is about 250 nA.

31. The method of claim 16, further comprising measuring the output signal intermittently.

32. The method of claim 31, further comprising measuring at least eight current values in at least one pulse of the output signal.

33. The method of claim 16, further comprising determining a difference between at least one base output value and at least one measured output value of the output signal.

34. The method of claim 16, further comprising dividing at least one output value in a pulse of the output signal by the first output value in the pulse of the output signal.

35. The method of claim 16, where the output signal comprises at least five pulses.

36. The method of claim 35, where the normalized current value of the fourth pulse, R₄, is represented by the following equation:

37. The method of claim 35, where the normalized current value of the fifth pulse, R₅, is represented by the following equation:

38. The method of claim 35, where the ratio of the normalized current value of the fourth pulse to the normalized current value of the fifth pulse is represented by the following equation:

40. A biosensor for determining an analyte concentration in a biological fluid, comprising:

a sensor strip having a sample interface on a base, where the sample interface is adjacent to a reservoir formed by the base;

a measuring device having a processor connected to a sensor interface, where the sensor interface has electrical communication with the sample interface; and

where the processor normalizes an output signal from a redox reaction of an analyte in a sample of a biological fluid,

where the processor compares a normalized output signal to at least one control limit, and

where the processor generates an error signal when the normalized output signal is not within the at least one control limit.

41-58. -58. (canceled)