Gated Voltammetry

• US 20080179197A1
• Filed: 02/26/2008
• Published: 07/31/2008
• Est. Priority Date: 09/30/2005
• Status: Active Grant

• Current Assignee: Ascensia Diabetes Care Holdings AG (PHC Holdings Corporation)
• Original Assignee: Bayer Healthcare LLC Diabetes Cares Division
• Inventors: WU, Huan-Ping
• Granted Patent: US 8,404,100 B2
• Time in Patent Office: Days
• US Class Current: 205/775
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• 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: 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 27/413 Concentration cells using liquid electrolytes measuring currents or voltages in voltaic cells
• CPC Class Codes: G01N 33/5438 Electrodes

Abstract

A sensor system, device, and methods for determining the concentration of an analyte in a sample is described. Gated voltammetric pulse sequences including multiple duty cycles of sequential excitations and relaxations may provide a shorter analysis time and/or improve the accuracy and/or precision of the analysis. The disclosed pulse sequences may reduce analysis errors arising from the hematocrit effect, variance in cap-gap volumes, non-steady-state conditions, mediator background, a single set of calibration constants, under-fill, and changes in the active ionizing agent content of the sensor strip.

Claims

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

applying a pulse sequence to the sample, the pulse sequence comprising at least two duty cycles;

measuring resulting currents; and

determining the concentration of the analyte in the sample.

2. The method of claim 1, where each of the duty cycles comprise an excitation from 0.1 to 1.5 seconds.

3. The method of claim 1, where each of the duty cycles comprise a relaxation of at least 1 second.

5. The method of claim 1, where the pulse sequence comprises at least three duty cycles within 5 seconds or less.

8. The method of claim 1, where the concentration of the analyte determined from the method includes less bias attributable to mediator background than a concentration of the analyte determined from another method lacking the pulse sequence comprising at least two duty cycles.

28. The method of claim 1, further comprising determining the active ionizing agent content of a sensor strip.

29. The method of claim 28, where the determining of the active ionizing agent content of the sensor strip includes determining a ratio from forward and reverse scan current values.

30. The method of claim 29, where the ratio was previously correlated to known amounts of the active ionizing agent.

31. The method of claim 29, where a calibration slope is altered in response to the active ionizing agent content of the sensor strip.

32. The method of claim 1, where the excitation/relaxation time ratio of the duty cycles is from 0.3 to 0.2.

4. (canceled)

6-7. -7. (canceled)

9-26. -26. (canceled)

33. A handheld analyte measuring device, for determining the concentration of an analyte in a sample, comprising a gated oltammetric measuring device adapted to receive a sensor strip, where

the gated oltammetric measuring device comprises at least two device contacts in electrical communication with a display through electrical circuitry, and

the sensor strip comprises at least first and second sensor strip contacts, the first sensor strip contact in electrical communication with a working electrode and the second sensor strip contact in electrical communication with a counter electrode through conductors, where

a first reagent layer is on at least one of the electrodes, the first reagent layer comprises an oxidoreductase and at least one species of a redox pair.

34-35. -35. (canceled)

36. A handheld measuring device, for determining the concentration of an analyte in a sample, where

the device is adapted to receive a sensor strip and the device comprises:

at least two contacts;

at least one display; and

electrical circuitry establishing electrical communication between the at least two contacts and the at least one display, where the electrical circuitry includes a processor in electrical communication with an electric charger and a computer readable storage medium,

where the processor is operable to implement a pulse sequence from the electric charger to the at least two contacts, where the pulse sequence comprises at least two duty cycles,

where the processor is operable to measure at least one current profile at the at least two contacts, and

where the processor is operable to determine the analyte in the sample in response to the at least one current profile.

38. The device of claim 36, where the processor is operable to apply at least one data treatment selected from the group consisting of semi-integral, semi-derivative, and derivative to the current profile to determine the analyte in the sample.

37. (canceled)

39. A method of reducing the bias attributable to mediator background in a determined concentration of an analyte in a sample comprising:

applying a gated voltammetric pulse sequence to the sample, the pulse sequence comprising at least two duty cycles.

40. A method of determining the duration of a pulse sequence including at least two duty cycles, for determining the concentration of an analyte in a sample comprising:

determining a plurality of calibration sets determined from currents recorded during the at least two duty cycles; and

determining the duration of the pulse sequence in response to the determined concentration of the analyte in the sample.

41. (canceled)

42. A method of signaling a user to add additional sample to a sensor strip, comprising:

determining if the sensor strip is under-filled by comparing at least one current value recorded from a pulse sequence including at least two duty cycles to a pre-selected value; and

signaling the user to add additional sample to the sensor strip if the strip is under-filled.

43-45. -45. (canceled)

46. A voltammetric method for determining the concentration of an analyte in a sample, comprising:

applying a pulse sequence to the sample, the pulse sequence comprising at least two duty cycles having excitation/relaxation time ratios from 0.3 to 0.2;

measuring resulting currents; and

determining the concentration of the analyte in the sample.

47. The method of claim 46, where the concentration of the analyte determined from the method is more accurate than a concentration of the analyte determined from another method where the excitation/relaxation time ratio of a pulse is greater than 0.3.

48. In an electrochemical method for determining the concentration of an analyte in a sample, the improvement comprising applying a gated voltammetric pulse sequence to the sample comprising at least two duty cycles.