Accurate Analyte Measurements for Electrochemical Test Strip Based on Sensed Physical Characteristic(s) of the Sample Containing the Analyte and Derived BioSensor Parameters

• US 20140284223A1
• Filed: 12/28/2012
• Published: 09/25/2014
• Est. Priority Date: 12/29/2011
• Status: Active Grant

• Current Assignee: Cilag Gmbh International (Johnson & Johnson)
• Original Assignee: LifeScan Scotland Limited (Johnson & Johnson)
• Inventors: Malecha, Michael, Smith, Antony, McColl, David
• Granted Patent: US 9,903,831 B2
• Time in Patent Office: Days
• US Class Current: 205/782
• CPC Class Codes: G01N 27/26 by investigating electrochemical variables; by using electrolysis or electrophoresis
• CPC Class Codes: G01N 27/3272 Test elements therefor, i.e. disposable laminated substrates with electrodes, reagent and channels optical biosensors G01N33/52
• 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: G16B 40/00 ICT specially adapted for biostatistics; ICT specially adapted for bioinformatics-related machine learning or data mining, e.g. knowledge discovery or pattern finding
• CPC Class Codes: G16B 40/10 Signal processing, e.g. from mass spectrometry [MS] or from PCR

Abstract

Various embodiments for a method that allow for a more accurate analyte concentration with a biosensor by determining at least one physical characteristic, typically hematocrit, of the sample containing the analyte and deriving from this characteristic a parameter relating to the biosensor to attain accurate glucose concentration.

Claims

1. A method of determining an analyte concentration from a fluid sample with a biosensor having at least two electrodes and a reagent disposed on at least one of the electrodes, the method comprising:

depositing a fluid sample on at least one electrode to start an analyte test sequence;

applying a signal to the sample to determine a physical characteristic of the sample;

driving another signal to the sample to cause a physical transformation of the sample;

measuring at least one output signal from the sample;

obtaining an estimated analyte concentration from the at least one output signal at one of a plurality of predetermined time positions from the start of the test sequence and at least one predetermined parameter of the biosensor;

generating a first parametric factor of the biosensor based on the physical characteristic of the sample;

calculating a first analyte concentration based on the first parametric factor of the biosensor and at least one output signal measured at one of the plurality of predetermined time positions from the start of the test sequence;

generating a second parametric factor of the biosensor based on the estimated analyte concentration and the physical characteristic of the sample;

calculating a second analyte concentration based on the second parametric factor of the biosensor and at least one output signal measured at one of the plurality of predetermined time positions from the start of the test sequence;

generating a third parametric factor of the biosensor based on the first analyte concentration and the physical characteristic;

calculating a third analyte concentration based on the third parametric factor of the biosensor and at least one output signal measured at one of the plurality of predetermined time positions from the start of the test sequence; and

annunciating at least one of the first, second, and third analyte concentrations.

22. The method of claim 1, in which the calculating of the first analyte concentration may be calculated from an equation of the form:

2. A method of determining an analyte concentration from a fluid sample with a biosensor having at least two electrodes and a reagent disposed on at least one of the electrodes, the method comprising:

starting an analyte test sequence upon deposition of a sample;

applying a signal to the sample to determine a physical characteristic of the sample;

driving another signal to the sample to cause a physical transformation of the sample;

measuring at least one output signal from the sample;

deriving an estimated analyte concentration from the at least one output signal measured at one of a plurality of predetermined time positions from the start of the test sequence;

obtaining a new parameter of the biosensor based on the estimated analyte concentration and the physical characteristic of the sample;

calculating an analyte concentration based on the new parameter of the biosensor and a output signal measured at the one or another of the plurality of predetermined time positions from the start of the test sequence; and

annunciating the analyte concentration.

21. The method of claim 2, in which the calculating of the estimated analyte concentration may be calculated from an equation of the form:

23. The method of claim 2, in which the calculating of the second analyte concentration may be calculated with an equation of the form:

3. A method of determining an analyte concentration from a fluid sample with a biosensor having at least two electrodes and a reagent disposed on at least one of the electrodes, the method comprising:

starting an analyte test sequence upon deposition of a sample on the biosensor;

applying a signal to the sample to determine a physical characteristic of the sample;

driving another signal to the sample to cause a physical transformation of the sample;

measuring at least one output signal from the sample;

generating a first new batch parameter of the biosensor based on the physical characteristic of the sample;

calculating a first analyte concentration based on the first new batch parameter of the biosensor and an output signal measured at one of a plurality of predetermined time positions from the start of the test sequence; and

annunciating the first analyte concentration.

4. The method of claim 3, further comprising:

generating a third parameter of the biosensor based on the physical characteristic and the first analyte concentration;

calculating a third analyte concentration based on the third parameter of the biosensor a and a output signal measured at one of a plurality of predetermined time positions from the start of the test sequence; and

annunciating the third analyte concentration instead of the first analyte concentration.

5. The method of claim 3, in which the parameter of the biosensor comprises a batch slope and the new parameter of the biosensor comprises a new batch slope.

6. The method of claim 5, in which the applying of the first signal and the driving of the second signal may be in sequential order.

7. The method of claim 3, in which the applying of the first signal overlaps with the driving of the second signal.

8. The method of claim 3, in which the applying of the first signal comprises directing an alternating signal to the sample so that a physical characteristic of the sample may be determined from an output of the alternating signal.

in which the physical characteristic comprises at least one of viscosity, hematocrit, temperature, and density of the sample, or combinations thereof.

9. The method of claim 5, in which the physical characteristic comprises an impedance characteristic representative of hematocrit of the sample and the analyte comprises glucose.

10. The method of claim 9, in which the impedance characteristic of the sample may be determined with an equation of the form:

IC=M²*y₁+M*y₂+y₃+P²*y₄+P*y₅ 

 

Eq. 4.2

where;

IC represents the impedance characteristic;

M represents a magnitude |Z| of a measured impedance in ohms);

P represents a phase difference between the input and output signals (in degrees);

y₁ may be about −

3.2e−

08 and ±

10%, 5% or 1% of the numerical value provided hereof (and depending on the frequency of the input signal, can be zero or even negative);

y₂ may be about 4.1e−

03 and ±

10%, 5% or 1% of the numerical value provided hereof (and depending on the frequency of the input signal, can be zero or even negative);

y₃ may be about −

2.5e+01 and ±

10%, 5% or 1% of the numerical value provided hereof;

y₄ may be about 1.5e−

01 and ±

10%, 5% or 1% of the numerical value provided hereof (and depending on the frequency of the input signal, can be zero or even negative); and

y₅ may be about 5.0 and ±

10%, 5% or 1% of the numerical value provided hereof (and depending on the frequency of the input signal, can be zero or even negative).

11. The method of claim 9, in which the physical characteristic represented by H is generally equal to an impedance characteristic determined by an equation of the form:

12. The method of claim 9, in which the directing comprises driving first and second alternating signals at different respective frequencies in which a first frequency may be lower than the second frequency.

13. The method of claim 12, in which the first frequency may be at least one order of magnitude lower than the second frequency.

14. The method of claim 13, in which the first frequency comprises any frequency in the range of about 10 kHz to about 250 kHz.

15. The method of claim 5, in which the one of the plurality of predetermined time positions for measuring at least one output signal during the test sequence may be about 2.5 seconds after a start of the test sequence.

16. The method of claim 15, in which the one of the plurality of predetermined time positions comprises a time interval that overlaps a time point of 2.5 seconds after the start of the test sequence.

17. The method of claim 5, in which the other one of the plurality of predetermined time positions for measuring at least one output signal during the test sequence may be a time point of about 5 seconds after a start of the test sequence.

18. The method of claim 5, in which the one of the plurality of predetermined time positions comprises any time point at less than five seconds from a start of the test sequence.

19. The method of claim 5, in which the other one of the plurality of predetermined time positions comprises any time point at less than ten seconds from a start of the test sequence.

20. The method of claim 19, in which the one of the plurality of predetermined time positions comprises a time interval overlapping a time point of 2.5 seconds after the start of the test sequence and the other of the plurality of predetermined time positions comprises a time interval overlapping a time point of 5 seconds after the start of the test sequence.

24. The method of claim 4, in which the calculating of the third analyte concentration may be calculated with an equation of the form:

25. The method of claim 5, in which the at least two electrodes and the at least two other electrodes are disposed in the same chamber provided on the substrate.

26. The method of claim 3, in which the at least two electrodes

comprise two electrodes to measure the physical characteristic and the analyte concentration.

27. The method of claim 3, in which the at least two electrodes comprise a first set of at least two electrodes to determine the physical characteristic of the sample and a second set of at least two other electrodes to determine the analyte concentration.

28. The method of claim 27, in which all of the electrodes are disposed on a same plane defined by a substrate of the biosensor.

29. The method of claim 26, in which a third electrode may be disposed proximate the first set of at least two electrodes and connected to the second set of at least two other electrodes.

30. The system of claim 28, in which a reagent may be disposed proximate the at least two other electrodes and no reagent may be disposed on the at least two electrodes.

31. An analyte measurement system comprising:

a test strip including;

a substrate;

a plurality of electrodes connected to respective electrode connectors; and

an analyte meter including;

a housing;

a test strip port connector configured to connect to the respective electrode connectors of the test strip; and

a microprocessor in electrical communication with the test strip port connector to apply electrical signals or sense electrical signals from the plurality of electrodes during a test sequence,

wherein the microprocessor may be configured, during the test sequence, to;

(a) start an analyte test sequence upon deposition of a sample;

(b) apply a signal to the sample to determine a physical characteristic of the sample;

(c) drive another signal to the sample;

(d) measure at least one output signal from at least one of the electrodes;

(e) derive an estimated analyte concentration from the at least one output signal at one of a plurality of predetermined time positions from the start of the test sequence;

(f) obtain a new parameter of the biosensor based on the estimated analyte concentration and the physical characteristic of the sample;

(g) calculate an analyte concentration based on the new parameter of the biosensor and a output signal measured at the one or another of the plurality of predetermined time positions from the start of the test sequence; and

(h) annunciate the analyte concentration.

32. The system of claim 31, in which the plurality of electrodes comprises at least two electrodes to measure the physical characteristic and at least two other electrodes to measure the analyte concentration.

33. The system of claim 32, in which the at least two electrodes and the at least two other electrodes are disposed in the same chamber provided on the substrate.

34. The system of claim 31, in which the plurality of electrodes comprises two electrodes to measure the physical characteristic and the analyte concentration.

35. The system of claim 34, in which all of the electrodes are disposed on the same plane defined by the substrate.

36. The system of claim 35, in which a reagent may be disposed proximate the at least two other electrodes and no reagent may be disposed on the at least two electrodes.

37. The system of claim 31, in which the one of the plurality of predetermined time positions for measuring at least one output signal during the test sequence may be about 2.5 seconds after the start of the test sequence.

38. The system of claim 31, in which the one of the plurality of predetermined time positions comprises a time interval that overlaps a time point of 2.5 seconds after the start of the test sequence.

39. The system of claim 31, in which the other one of the plurality of predetermined time positions for measuring at least one output signal during the test sequence may be a time point of about 5 seconds after a start of the test sequence.

40. The system of claim 31, in which the one of the plurality of predetermined time positions comprises any time point at less than five seconds from a start of the test sequence.

41. The system of claim 31, in which the other one of the plurality of predetermined time positions comprises any time point at less than ten seconds from a start of the test sequence.

42. The system of claim 41, in which the one of the plurality of predetermined time positions comprises a time interval overlapping a time point of 2.5 seconds after the start of the test sequence and the other of the plurality of predetermined time positions comprises a time interval overlapping a time point of 5 seconds after the start of the test sequence.

43-51. -51. (canceled)