Devices and methods relating to electrochemical biosensors

• US 20050023152A1
• Filed: 06/18/2004
• Published: 02/03/2005
• Est. Priority Date: 06/20/2003
• Status: Active Grant

• Current Assignee: Roche Diabetes Care Inc. (Roche Holding AG)
• Original Assignee: Roche Diagnostics Operations Incorporated (Roche Holding AG)
• Inventors: Sullivan, Melani, Surridge, Nigel Anthony, Hill, Brian S., Walling, Paul Douglas, Svetnik, Vladimir
• Granted Patent: US 8,506,775 B2
• Time in Patent Office: Days
• US Class Current: 205/775
• CPC Class Codes: C12M 1/00 Apparatus for enzymology or microbiology
• CPC Class Codes: C12Q 1/001 Enzyme electrodes
• CPC Class Codes: G01N 27/3272 Test elements therefor, i.e. disposable laminated substrates with electrodes, reagent and channels optical biosensors G01N33/52

Abstract

A system for testing for analytes in a sample of biological fluid includes a test strip that defines a cavity for receiving the sample. At least two sets of electrodes are adjacent the sample cavity, including one for measuring one property of the sample, and another for measuring one or more other properties of the sample, such as temperature and/or the presence or magnitude of confounding variables. The measurements are combined to yield the desired result. At least one set of working and counter electrodes each have a plurality of elongated “fingers” interdigitated with those of the other electrode in the set. The gaps between fingers can be quite small, so that the two electrode sets together can operate in a small measurement volume of sample. Additional electrodes can be included that measure the presence or sufficiency of the sample, and additional traces on the strip can act as configuration identifiers.

Claims

1. In a test strip that defines a capillary passageway, the passageway being dimensioned so as to induce movement of a sample of bodily fluid along a predetermined path through the passageway, the improvement comprising:

a first set of electrodes in electrical communication with the passageway for obtaining a first measurement correlated with the concentration of an analyte in the sample; and

a second set of electrodes in electrical communication with the passageway for obtaining a second measurement correlated with the analyte and one or more properties of the sample.

2. The test strip of claim 1, wherein the second set of electrodes comprises a pair of electrodes with substantially parallel, interdigitated fingers, each electrode having at least two fingers, and each of the fingers being less than about 50 μ

m from the nearest other finger in the second set of electrodes.

3. The test strip of claim 2, wherein the first set of electrodes comprises a pair of electrodes with substantially parallel, interdigitated fingers, each electrode having at least two fingers, and each of the fingers being less than about 50 μ

m from the nearest other finger in the first set of electrodes.

4. The test strip of claim 3, wherein each of the fingers is at least about 1 μ

m from the nearest other finger in the first set of electrodes.

5. The test strip of claim 3, wherein each of the fingers is at least about 10 μ

m from the nearest other finger in the first set of electrodes.

6. The test strip of claim 1, wherein the second set of electrodes comprises a pair of electrodes with substantially parallel, interdigitated fingers, each electrode having at least two fingers, and each of the fingers being less than about 50 μ

m in width.

7. The test strip of claim 6, wherein the first set of electrodes comprises a pair of electrodes with substantially parallel, interdigitated fingers, each electrode having at least two fingers, and each of the fingers being less than about 50 μ

m in width.

8. The test strip of claim 6, wherein each of the fingers is at least about 1 μ

m from the nearest other finger in the first set of electrodes.

9. The test strip of claim 8, wherein each of the fingers is at least about 10 μ

m from the nearest other finger in the first set of electrodes.

10. The test strip of claim 1, further comprising a third set of electrodes in electrical communication with the path for determining when a sample has entered a predetermined distance into the passage.

11. The test strip of claim 10, wherein the third set of electrodes is selected from the group consisting of the first set of electrodes and the second set of electrodes.

12. The test strip of claim 10, wherein the third set of electrodes is a single electrode that is closer to the entrance of the passageway than both the first set of electrodes and the second set of electrodes.

13. The test strip of claim 12, wherein the single electrode has one or more electrically connected fingers, each finger having a width between about 5 μ

m and about 50 μ

m.

14. The test strip of claim 10, wherein the third set of electrodes comprises a first dose-detect electrode and a second dose-detect electrode, both of which are closer to the entrance of the passage than both the first set of electrodes and the second set of electrodes.

15. The test strip of claim 14, wherein the dose detect working electrode and the dose detect counter electrode each have a plurality of electrically connected fingers, each finger being substantially rectangular in shape and having a width between about 5 μ

m and about 50 μ

m.

16. The test strip of claim 1, further comprising a third set of electrodes in electrical communication with the path for determining when a sample has filled the passage to cover the first set of electrodes and the second set of electrodes.

17. The test strip of claim 16, wherein the third set of electrodes is the selected from the group consisting of the first set of electrodes and the second set of electrodes.

18. The test strip of claim 16, wherein the third set of electrodes is a single electrode that is farther from the entrance of the passageway than both the first set of electrodes and the second set of electrodes.

19. The test strip of claim 18, wherein the single electrode has one or more electrically connected fingers, each finger being substantially rectangular in shape and having a width less than about 50 μ

m.

20. The test strip of claim 16, wherein the third set of electrodes comprises a sample sufficiency working electrode and a sample sufficiency counter electrode, both of which are farther from the entrance of the passage than both the first set of electrodes and the second set of electrodes.

21. The test strip of claim 20, wherein the sample sufficiency working electrode and the sample sufficiency counter electrode each have a plurality of electrically connected fingers, each finger being substantially rectangular in shape and having a width between about 5 μ

m and about 50 μ

m.

22. The test strip of claim 1, wherein:

the first set of electrodes comprises a first electrode and a second electrode;

the second set of electrodes comprises a third electrode and a fourth electrode;

the first electrode and the third electrode are electrically connected to each other; and

the second electrode and the fourth electrode are in electrical communication with each other.

23. The test strip of claim 1, further comprising reagent material over the first set of electrodes, where the reagent material combines with the bodily fluid to produce a redox reaction.

24. The test strip of claim 1, further comprising reagent material over the second set of electrodes, where the reagent material combines with the bodily fluid to produce a redox reaction.

25. A diagnostic strip, comprising:

a first electrode pair, comprising a first electrode and a second electrode, operating in a first substantially planar physical zone; and

a second electrode pair, comprising a third electrode and a fourth electrode, operating in a second substantially planar physical zone that is substantially co-planar with the first planar physical zone;

wherein the first electrode and the second electrode each include a plurality of fingers;

the third electrode and the fourth electrode each include at least one finger; and

the fingers of the first electrode and the second electrode being interdigitated, and being separated from their nearest adjacent fingers by at most about 50 μ

m at their nearest points.

26. The diagnostic strip of claim 25, wherein the first electrode pair is closer to the edge than the second electrode pair.

27. The diagnostic strip of claim 26, further comprising a fifth electrode situated farther from the edge than the first electrode pair and the second electrode pair.

28. The diagnostic strip of claim 27, wherein the fifth electrode is a single conductive lead.

29. The diagnostic strip of claim 28, wherein said fifth electrode has a width of at most about 50 μ

m.

30. The diagnostic strip of claim 28, wherein said fifth electrode has a width of at least about 50 μ

m.

31. The diagnostic strip of claim 27, wherein the fifth electrode is a plurality of conductive leads.

32. The diagnostic strip of claim 31, wherein the plurality of conductive leads:

each have a width of at most about 50 μ

m; and

are not all electrically connected to each other on the strip.

33. The diagnostic strip of claim 25, wherein the second electrode pair is closer to the edge than the first electrode pair.

34. The diagnostic strip of claim 33, wherein the second electrode pair comprises at least two fingers, each at least about 50 μ

m wide.

35. The diagnostic strip of claim 33, wherein the second electrode pair comprises at least two fingers, each at most about 50 μ

m wide.

36. The diagnostic strip of claim 33, further comprising a fifth electrode situated farther from the edge than the first electrode pair and the second electrode pair.

37. The diagnostic strip of claim 36, wherein the fifth electrode is a single conductive lead.

38. The diagnostic strip of claim 37, wherein said fifth electrode has a width of at most about 50 μ

m.

39. The diagnostic strip of claim 37, wherein said fifth electrode has a width of at least about 50 μ

m.

40. The diagnostic strip of claim 36, wherein the fifth electrode is a plurality of conductive leads.

41. The diagnostic strip of claim 40, wherein the plurality of conductive leads:

extend parallel to the edge;

have a width of at most about 50 μ

m; and

are not electrically connected to each other on the strip.

42. The diagnostic strip of claim 25, wherein:

the third electrode and the fourth electrode each comprise one or more fingers; and

the fingers of the third electrode and the fingers of the fourth electrode each have a width of at least about 50 μ

m.

43. The diagnostic strip of claim 25, wherein:

the third electrode and the fourth electrode each comprise one or more fingers; and

the fingers of the third electrode and fingers of the fourth electrode each have a width of at most about 50 μ

m.

44. The diagnostic strip of claim 25, wherein the fingers of the first electrode and the second electrode are each separated from their nearest neighboring fingers by at most about 30 μ

m at their nearest points.

45. The diagnostic strip of claim 25, wherein:

the fingers of the first electrode and the second electrode are substantially rectangular in shape and at most about 20 μ

m wide; and

the fingers of the first electrode and the second electrode are each separated from their nearest neighbors by at most about 20 μ

m at their nearest points.

46. The diagnostic strip of claim 25:

further comprising a first electrical contact and a second electrical contact on the strip spaced apart from the first and second electrode pairs;

wherein the first electrode and the third electrode are electrically connected to the first electrical contact, and the second electrode and the fourth electrode are electrically connected to the second electrical contact.

47. The diagnostic strip of claim 25:

further comprising a first electrical contact, a second electrical contact, a third electrical contact, and a fourth electrical contact on the strip spaced apart from the first and second electrode pairs;

wherein the first electrode is electrically connected to the first electrical contact, the second electrode is electrically connected to the second electrical contact, the third electrode is electrically connected to the third electrical contact, and the fourth electrode is electrically connected to the fourth electrical contact.

48. The test strip of claim 25, further comprising reagent material over the first electrode pair, where the reagent material combines with the bodily fluid to produce a redox reaction.

49. The test strip of claim 25, further comprising a first reagent material over the second electrode pair, wherein the first reagent material combines with the bodily fluid to produce a redox reaction.

50. The test strip of claim 49, further comprising a second reagent material over the first electrode pair.

51. The test strip of claim 50, wherein the first reagent material and the second reagent material are the same material.

52. The test strip of claim 50, wherein the second reagent material combines with the bodily fluid to produce a redox reaction.

53. A test strip, comprising:

a first electrode means for measuring concentration of an analyte; and

a second electrode means for determining a correction factor by measuring an electrical response that reaches a steady state or quasi-steady state condition in less than 4.00 seconds.

54. The test strip of claim 53, wherein the second electrode response reaches a steady state or quasi-steady state in less than 3.00 seconds.

55. The test strip of claim 53, wherein the second electrode response reaches a steady state or quasi-steady state in less than 2.00 seconds.

56. The test strip of claim 53, wherein the second electrode response reaches a steady state or quasi-steady state in less than 1.00 seconds.

57. The test strip of claim 53, wherein the second electrode response reaches a steady state or quasi-steady state in less than 0.50 seconds.

58. A test strip, comprising:

a first sensor adapted to test a sample of a bodily fluid in a first measurement region of a sample cavity; and

a second sensor adapted to test the same sample within a second measurement region of the sample cavity;

a wherein the first measurement region and second measurement region total at most about 240 nL.

59. The test strip of claim 58, wherein the total measurement volume is at most about 200 nL.

60. The test strip of claim 58, wherein the total measurement volume is at most about 90 nL.

61. The test strip of claim 58, wherein the total measurement volume is at most about 80 nL.

62. The test strip of claim 58, wherein the total measurement volume is at most about 65 nL.

63. The test strip of claim 58, wherein:

the first sensor comprises a working electrode and a counter electrode; and

the second sensor comprises a single lead.

64. The test strip of claim 58, wherein:

the first sensor comprises a first working electrode and a first counter electrode; and

the second sensor comprises a second working electrode and a second counter electrode.

65. The test strip of claim 64, wherein the second working electrode and the second counter electrode are interdigitated arrays of conductive fingers, each finger being substantially rectangular in shape and having a width between about 5 μ

m and about 50 μ

m.

66. A method of measuring concentration of an analyte in a sample of bodily fluid, comprising:

obtaining a first response to an application of a first electrical signal to the sample;

obtaining a second response to an application of a second electrical signal to the sample; and

using the first response and the second response to derive a measurement of the concentration of the analyte in the sample.

67. The method of claim 66, wherein the obtaining steps are performed in overlapping periods of time.

68. The method of claim 66, wherein:

the first electrical signal is applied through a first electrode pair in electrical contact with the sample;

the second electrical signal is applied through a second electrode pair in electrical contact with the sample; and

the volume of the sample is less than about 240 nL.

69. The method of claim 68, wherein the volume of the sample is less than about 200 nL.

70. The method of claim 68, wherein the volume of the sample is less than about 90 nL.

71. The method of claim 68, wherein the volume of the sample is less than about 80 nL.

72. The method of claim 68, wherein the volume of the sample is less than about 65 nL.

73. The method of claim 66, further comprising:

before the obtaining steps, detecting the sufficiency of the volume of the sample.

74. The method of claim 73, wherein the detecting is performed using at least a third electrode.

75. The method of claim 74, wherein the detecting is performed using a third electrode pair.

76. A sensor for measuring concentration of an analyte in a sample of bodily fluid, comprising:

a first electrode pair configured to apply a first signal to the sample to elicit a first response that indicates the approximate concentration of the analyte in the sample; and

a second electrode pair configured to apply a second signal to the sample to elicit a second response that indicates a second property of the sample, where the second property affects the first response;

wherein at least one of the first response and the second response reaches a steady state less than 4.00 seconds after the corresponding signal is applied.

77. The sensor of claim 76, wherein the at least one of the first response and the second response reaches a steady state in less than 3.00 seconds.

78. The sensor of claim 76, wherein the at least one of the first response and the second response reaches a steady state in less than 2.00 seconds.

79. The sensor of claim 76, wherein the at least one of the first response and the second response reaches a steady state in less than 1.00 seconds.

80. The sensor of claim 76, wherein the at least one of the first response and the second response reaches a steady state in less than 0.50 seconds.

81. A method of measuring concentration of an analyte in a sample of bodily fluid, comprising:

a first electrode pair configured to apply a first signal to the sample to elicit a first response that indicates the approximate concentration of the analyte in the sample;

a second electrode pair configured to apply a second signal to the sample to elicit a second response that has a different sensitivity to one or more properties of the sample; and

using the first response and the second response to derive a corrected measurement of the concentration of the analyte in the sample;

wherein at least one of the first response and the second response reaches a steady state or quasi-steady state in less than 4.00 seconds.

82. The sensor of claim 81, wherein the at least one of the first response and the second response reaches a steady state or quasi-steady state in less than 3.00 seconds.

83. The sensor of claim 81, wherein the at least one of the first response and the second response reaches a steady state or quasi-steady state in less than 2.00 seconds.

84. The sensor of claim 81, wherein the at least one of the first response and the second response reaches a steady state or quasi-steady state in less than 1.00 seconds.

85. The sensor of claim 81, wherein the at least one of the first response and the second response reaches a steady state or quasi-steady state in less than 0.50 seconds.