Measuring device and methods for use therewith

• US 7,964,146 B2
• Filed: 04/15/2005
• Issued: 06/21/2011
• Est. Priority Date: 05/30/2004
• Status: Active Grant

• Current Assignee: Agamatrix Incorporated (AgaMatrix Holdings LLC d/b/a WaveForm Diabetes)
• Original Assignee: Agamatrix Incorporated (AgaMatrix Holdings LLC d/b/a WaveForm Diabetes)
• Inventors: Flaherty, Joseph, Vu, Sonny, Huang, Eileen, Diamond, Steven, Harding, Ian, Wei, Baoguo, Forest, Martin, Iyengar, Sridhar G.
• Primary Examiner(s): Bullock; In Suk
• Assistant Examiner(s): Hyun; Paul S
• Application Number:
  US10/907,790
• Publication Number:
  US 20050265094A1
• Time in Patent Office: 2,258 Days
• Field of Search: 204409-412, 204/400, 205/775, 205/792, 422/82.01
• US Class Current: 422/82.01
• CPC Class Codes: G01N 27/28 Electrolytic cell components
• CPC Class Codes: G01N 27/3271 Amperometric enzyme electrodes for analytes in body fluids, e.g. glucose in blood amperometry per se G01N27/49; aspects concerning the enzyme reagent C12Q1/001
• 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 27/3273 Devices therefor, e.g. test element readers, circuitry details not specific to biochemical electrodes G01N33/4875
• CPC Class Codes: G01N 27/403 Cells and electrode assemblies
• CPC Class Codes: G01N 33/50 Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing measuring or testing processes involving enzymes or microorganisms, compositions or test papers therefor; processes for forming such compositions, condition responsive control in microbiological or enzymological processes C12Q

Abstract

The ability to switch at will between amperometric measurements and potentiometric measurements provides great flexibility in performing analyses of unknowns. Apparatus and methods can provide such switching to collect data from an electrochemical cell. The cell may contain a reagent disposed to measure glucose in human blood.

Claims

1. A method for use in a handheld test equipment apparatus having an electrochemical cell disposed to receive a bodily fluid of a human user, said electrochemical cell comprising first and second electrodes and a reagent reactive with an analyte in the bodily fluid to yield a current in response to an applied potential when the analyte is present, the apparatus comprising electronic circuitry, the method comprising the steps of:

under automatic control of the electronic circuitry, applying a potential to the electrochemical cell by means of a source of potential external to the cell and measuring said current indicative of the presence of analyte;

thereafter, under automatic control of the electronic circuitry, ceasing the application of the potential to the cell;

thereafter, under automatic control of the electronic circuitry, measuring a decay in chemical potential at the cell; and

evaluating the measured current and the measured decay of chemical potential to evaluate a measure of the analyte in the bodily fluid.

2. The method of claim 1 wherein the bodily fluid is blood.

3. The method of claim 2 wherein the electrochemical cell comprises a reagent reactive with glucose, and the evaluated characteristic of the blood is a concentration of glucose in the blood.

4. The method of claim 1 wherein the bodily fluid is urine.

5. The method of claim 1 wherein the potential is application as a time-variant voltage to the cell.

6. The method of claim 5 wherein the voltage applied to the cell comprises a sinusoidal potential.

7. The method of claim 5 wherein the voltage applied to the cell comprises a ramp potential.

8. The method of claim 1 wherein the test equipment comprises a housing and the electrochemical cell is within a test strip external to the housing, the method further comprising the steps, performed before the step of applying potential to the cell, of:

inserting the test strip into a connector at the housing, and

applying the bodily fluid to the electrochemical cell.

9. The method of claim 8 further comprising the step, performed after the step of measuring the decay of chemical potential at the cell, of:

removing the test strip from the housing.

10. The method of claim 1 wherein the step of ceasing application of potential to the cell further comprises:

opening a first switch whereby at least the first electrode of the electrochemical cell is isolated from the source of potential external to the cell.

11. The method of claim 10 wherein the step of ceasing application of potential to the cell further comprises:

opening a second switch whereby at least the second electrode of the electrochemical cell is isolated from the current source or source of potential external to the cell.

12. The method of claim 10 wherein the first electrode comprises a working electrode.

13. The method of claim 12 wherein the second electrode comprises a reference electrode.

14. The method of claim 12 wherein the second electrode comprises a counter electrode.

15. The method of claim 10 wherein the first electrode comprises a reference electrode.

16. The method of claim 15 wherein the second electrode comprises a working electrode.

17. The method of claim 15 wherein the second electrode comprises a counter electrode.

18. The method of claim 10 wherein the first electrode comprises a counter electrode.

19. The method of claim 18 wherein the second electrode comprises a reference electrode.

20. The method of claim 18 wherein the second electrode comprises a working electrode.

21. The method of claim 12 wherein the step of measuring decay of chemical potential at the cell comprises measuring a potential between the working electrode and a reference electrode.

22. The method of claim 12 wherein the step of measuring decay of chemical potential at the cell comprises measuring a potential between the working electrode and a counter electrode.

23. The method of claim 15 wherein the step of measuring decay of chemical potential at the cell comprises measuring a potential between the reference electrode and a working electrode.

24. The method of claim 15 wherein the step of measuring decay of chemical potential at the cell comprises measuring a potential between the reference electrode and a counter electrode.

25. The method of claim 18 wherein the step of measuring decay of chemical potential at the cell comprises measuring a potential between the counter electrode and a reference electrode.

26. The method of claim 18 wherein the step of measuring decay of chemical potential at the cell comprises measuring a potential between the counter electrode and a working electrode.

27. The method of claim 1 wherein the potential is applied to the cell as a constant voltage.

28. A handheld test equipment comprising:

an electrochemical cell comprising at least first and second electrodes and a reagent reactive with a constituent of a human bodily fluid;

a source of potential external to the electrochemical cell;

potentiometric circuitry external to the electrochemical cell;

electronic control means;

the electronic control means coupled with the source of potential to controllably apply the source of potential to the electrochemical cell, thereby allowing current to flow through the cell;

amperometric means external to the electrochemical cell for measuring the flow of current through the electrochemical cell;

wherein the electronic control means is coupled with the potentiometric circuitry to automatically cease application of potential to the electrochemical cell, and then cause the potentiometric circuitry to measure a decay in chemical potential at the electrochemical cell in the absence of the applied potential.

29. The handheld test equipment of claim 28 further comprising a housing, wherein the electrochemical test cell is part of a test strip, wherein the electrochemical test cell is external to the housing and wherein the test strip is electrically connected to a connector at the housing, the housing containing the source of potential, the potentiometric circuitry, and the electronic control means, and the potentiometric circuitry is disposed to measure potential at the first and second electrode.

30. The handheld test equipment of claim 29 wherein the first electrode comprises a working electrode.

31. The handheld test equipment of claim 30 wherein the second electrode comprises a reference electrode.

32. The handheld test equipment of claim 30 wherein the second electrode comprises a counter electrode.

33. The handheld test equipment of claim 29 wherein the first electrode comprises a counter electrode.

34. The handheld test equipment of claim 33 wherein the second electrode comprises a reference electrode.

35. The handheld test equipment of claim 33 wherein the second electrode comprises a working electrode.

36. The handheld test equipment of claim 29 wherein the first electrode comprises a reference electrode.

37. The handheld test equipment of claim 36 wherein the second electrode comprises a working electrode.

38. The handheld test equipment of claim 36 wherein the second electrode comprises a counter electrode.

39. The handheld test equipment of claim 29 further comprising a first switch selectively disconnecting the first electrode from the source of potential, to cease the application of potential to the electrochemical cell by opening the first switch.

40. The handheld test equipment of claim 39 further comprising a second switch selectively disconnecting the second electrode from the source of potential, to cease the application of potential to the electrochemical cell by opening the second switch.

41. The handheld test equipment of claim 28 wherein the source of potential comprises a constant-potential source.

42. The handheld test equipment of claim 28 wherein the source of potential comprises a source of time-variant potential.

43. The handheld test equipment of claim 42 wherein the source of potential comprises a source of sinusoidal potential.

44. The handheld test equipment of claim 42 wherein the source of potential comprises a source of ramp potential.

45. The handheld test equipment of claim 42 wherein the current source or source of potential comprises a digital-to-analog converter.

46. The handheld test equipment of claim 42 wherein the current source or source of potential comprises a pulse-width-modulated signal.

47. The handheld test equipment of claim 46 wherein the pulse-width-modulated signal is applied to a capacitor.

48. The handheld test equipment of claim 29 further comprising means logging the current and potential measurements and deriving a function of the logged measurements indicative of the constituent of the bodily fluid.

49. The handheld test equipment of claim 28 wherein the bodily fluid is blood.

50. The handheld test equipment of claim 28 wherein the bodily fluid is urine.

51. The handheld test equipment of claim 49 wherein the reagent is reactive with glucose, and the constituent of the bodily fluid is glucose.

52. The handheld test equipment of claim 48 wherein the logging means is within the housing.

53. The handheld test equipment of claim 48 wherein the logging means is outside the housing.

54. The handheld test equipment of claim 48 further comprising a display means communicatively coupled with the deriving means for displaying to a human user an indication of the constituent of the bodily fluid.

55. The handheld test equipment of claim 54 wherein the display means is outside the housing.

56. The handheld test equipment of claim 54 wherein the display means is within the housing.

75. The handheld test equipment of claim 47 wherein the pulse-width-modulated signal is applied to a capacitor.

57. A handheld test equipment comprising:

a housing;

a connector at the housing having at least first and second contacts;

a source of potential;

potentiometric circuitry within the housing;

electronic control means within the housing;

the electronic control means coupled with the current source or source of potential to controllably apply the source of potential to the at least first and second contacts;

amperometric means within the housing for measuring the current flowing through the at least first and second contacts;

wherein the electronic control means is coupled with the potentiometric circuitry to automatically cease application of the potential to the at least first and second contacts, and then cause the potentiometric circuitry to measure a decay of chemical potential at the at least first and second contacts in the absence of the applied current or potential.

58. The handheld test equipment of claim 57 further comprising a test strip external to the housing and electrically connected to the connector at the housing, the test strip comprising an electrochemical cell, the electrochemical cell in electrical connection with the at least first and second contacts.

59. The handheld test equipment of claim 58 wherein the electrochemical cell comprises at least a first and second electrode electrically connected with the at least first and second contacts respectively, the potentiometric circuitry disposed to measure potential at the first and second electrode.

60. The handheld test equipment of claim 59 wherein the first electrode comprises a working electrode.

61. The handheld test equipment of claim 60 wherein the second electrode comprises a reference electrode.

62. The handheld test equipment of claim 60 wherein the second electrode comprises a counter electrode.

63. The handheld test equipment of claim 59 wherein the first electrode comprises a counter electrode.

64. The handheld test equipment of claim 63 wherein the second electrode comprises a reference electrode.

65. The handheld test equipment of claim 63 wherein the second electrode comprises a working electrode.

66. The handheld test equipment of claim 59 wherein the first electrode comprises a reference electrode.

67. The handheld test equipment of claim 66 wherein the second electrode comprises a working electrode.

68. The handheld test equipment of claim 66 wherein the second electrode comprises a counter electrode.

69. The handheld test equipment of claim 57 further comprising a first switch selectively disconnecting the first contact from the source of potential to cease application of potential to the at least first and second contacts by opening the first switch.

70. The handheld test equipment of claim 69 further comprising a second switch selectively disconnecting the second contact from the source of potential to cease application of potential to the at least first and second contacts by opening the second switch.

71. The handheld test equipment of claim 57 wherein the source of potential comprises a source of time-variant potential.

72. The handheld test equipment of claim 71 wherein the source of potential comprises a digital-to-analog converter.

73. The handheld test equipment of claim 57 wherein the source of potential comprises a constant-potential source.

74. The handheld test equipment of claim 73 wherein the source of potential comprises a pulse-width-modulated signal.

76. The handheld test equipment of claim 57 further comprising means logging the current and potential measurements and deriving a function of the logged measurements indicative of the constituent of a bodily fluid.

77. The handheld test equipment of claim 76 wherein the bodily fluid is blood.

78. The handheld test equipment of claim 76 wherein the bodily fluid is urine.

79. The handheld test equipment of claim 77 constituent of the bodily fluid is glucose.

80. The handheld test equipment of claim 76 wherein the logging means is within the housing.

81. The handheld test equipment of claim 76 wherein the logging means is outside the housing.

82. The handheld test equipment of claim 76 further comprising a display means communicatively coupled with the deriving means for displaying to a human user an indication of the constituent of the bodily fluid.

83. The handheld test equipment of claim 82 wherein the display means is outside the housing.

84. The handheld test equipment of claim 82 wherein the display means is within the housing.

85. A test equipment comprising:

an electrochemical cell comprising first and second electrodes and a reagent reactive with a constituent of a human bodily fluid;

a source of potential external to the electrochemical cell;

potentiometric circuitry external to the electrochemical cell;

electronic control means;

the electronic control means coupled with the source of potential to controllably apply the potential to the electrochemical cell, thereby allowing current to flow through the cell in the presence of an analyte of interest;

amperometric means external to the electrochemical cell for measuring the current passed through the electrochemical cell;

wherein the electronic control means is coupled with the potentiometric circuitry to automatically cease application of potential to the electrochemical cell, and then cause the potentiometric circuitry to measure a decay in chemical potential at the electrochemical cell in the absence of the applied potential.