Method and system for interrogating electrochemical sensors

Abstract

This paper describes systems and methods for determining the amount of analyte in a sample using an electrochemical sensor. Many embodiments provide methods for interrogating an electrochemical sensor to determine the amount of analyte without the need to calibrate the sensor. The determination of the amount of analyte can be performed with improved temporal resolution.

Claims

1. A method for determining the amount of analyte in a sample: A step of interrogating the working electrode of an electrochemical sensor by applying a voltage perturbation, wherein the voltage perturbation is the sum of two or more sinusoidal waveforms, and each of the two or more sinusoidal waveforms has a different frequency; The steps include simultaneously measuring voltage and / or current values ​​across the working electrode and counter electrode at each of the different frequencies, The steps include: generating an impedance spectrum by applying an integral transform method to the measured voltage and / or current values ​​to determine the impedance at the frequencies of the two or more sinusoidal waveforms; The steps include determining the amount of the analyte in the sample using the impedance spectrum, and The method, including the method described above.

2. The method according to claim 1, wherein the integral transform method is selected from the Fourier transform, the Fast Fourier transform, the Laplace transform, the Mellin transform, the Hartley transform, and the Charplet transform.

3. The method according to claim 1 or claim 2, wherein the two or more sine waveforms are 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 or more sine waveforms.

4. The method according to any one of claims 1 to 3, wherein the frequencies of the two or more sinusoidal waveforms define a frequency range that includes frequencies that provide information on electron transfer dynamics between the redox reporter of the electrochemical sensor and the surface of the working electrode.

5. The method according to any one of claims 1 to 4, wherein the frequencies of the two or more sinusoidal waveforms define a frequency range that excludes frequencies that do not provide information on electron transfer dynamics between the redox reporter of the electrochemical sensor and the surface of the working electrode.

6. The method according to any one of claims 1 to 5, wherein the frequencies of the two or more sinusoidal waveforms define a frequency range that excludes frequencies that cause drift errors at the determined analyte concentration.

7. The method according to any one of claims 1 to 6, wherein the frequencies of the two or more sinusoidal waveforms are, each, 2000Hz, 1900Hz, 1800Hz, 1700Hz, 1600Hz, 1500Hz, 1400Hz, 1300Hz, 1200Hz, 1100Hz, 1000Hz, 900Hz, 800Hz, 700Hz, 600Hz, 500Hz, 400Hz, 300Hz, 200Hz, or less than 100Hz.

8. The method according to any one of claims 1 to 7, wherein the frequencies of the two or more sinusoidal waveforms are each 1 Hz to 2000 Hz, each 1 Hz to 1000 Hz, or each 10 Hz to 100 Hz.

9. The method according to any one of claims 1 to 8, wherein the frequencies of the two or more sinusoidal waveforms include a first frequency that provides information on electron transfer dynamics between the redox reporter of the electrochemical sensor and the surface of the working electrode, a second frequency that is higher than the first frequency, and a third frequency that is lower than the first frequency.

10. The method according to any one of claims 1 to 9, wherein the frequencies of the two or more sinusoidal waveforms include a lower frequency and one or more frequencies higher than the lower frequency, and each of the one or more frequencies higher than the lower frequency is a multiple of the lower frequency.

11. The method according to claim 10, wherein the lower frequency is the lowest of the frequencies of the two or more sinusoidal waveforms.

12. The method according to any one of claims 1 to 11, wherein the step of determining the amount of the analyte using the impedance spectrum includes the step of comparing the impedance spectrum or a portion thereof generated from a test sample with the impedance spectrum or a portion thereof generated from a control sample that does not contain the analyte.

13. The method according to claim 12, wherein both the impedance spectrum generated from the control sample and the impedance spectrum generated from the test sample are arranged as frequency versus phase.

14. The method according to claim 12 or 13, wherein the impedance spectrum generated from the control sample and the impedance spectrum generated from the test sample each include features at a first frequency and a second frequency, respectively, and the amount of the analyte is determined by referring to the difference between the first frequency and the second frequency.

15. The method according to claim 14, wherein the feature is a peak or maximum value, a trough or minimum value, an upward-sloping portion of the spectrum, or a downward-sloping portion of the spectrum.

16. The method according to any one of claims 1 to 15, wherein the step of determining the amount of analyte using the impedance spectrum includes the step of determining the electron transfer dynamics between the redox reporter of the electrochemical sensor and the surface of the working electrode using the spectrum.

17. The method according to claim 16, wherein the electron dynamics is the electron transfer rate between the redox reporter of the electrochemical sensor and the working electrode surface.

18. The method according to any one of claims 1 to 17, which allows for the repeated determination of the concentration of an analyte at intervals of 1 minute, 50 seconds, 40 seconds, 30 seconds, 20 seconds, 10 seconds, 9 seconds, 8 seconds, 7 seconds, 6 seconds, 5 seconds, 4 seconds, 3 seconds, 2 seconds, or less than 1 second.

19. The method according to any one of claims 1 to 18, comprising repeatedly determining the concentration of an analyte at intervals of 1 minute, 50 seconds, 40 seconds, 30 seconds, 20 seconds, 10 seconds, 9 seconds, 8 seconds, 7 seconds, 6 seconds, 5 seconds, 4 seconds, 3 seconds, 2 seconds, or less than 1 second.

20. The method according to any one of claims 1 to 19, comprising repeatedly determining the concentration of the analyte for at least 1 hour, 2 hours, 3 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours, 24 hours, 30 hours, 36 hours, 42 hours, or 48 hours.

21. The method according to any one of claims 1 to 20, wherein no frequency sweep step is required over a frequency range to determine the amount of analyte in the sample.

22. The method according to any one of claims 1 to 21, wherein no calibration step is required to determine the amount of analyte in the sample.

23. The method according to any one of claims 1 to 22, wherein no drift adjustment step is required to determine the amount of analyte in the sample.

24. The method according to any one of claims 1 to 23, wherein the sample is a bodily fluid from within or near the body of a subject.

25. The method according to claim 24, wherein the body fluid is selected from: interstitial fluid (ISF), blood, saliva, tear secretions, lactation secretions, nasal secretions, tracheal secretions, bronchial secretions, alveolar secretions, gastric secretions, gastric contents, glandular secretions, vaginal secretions, uterine secretions, prostatic secretions, semen, urine, sweat, cerebrospinal fluid, glomerular filtrate, hepatic secretions, bile, and intraocular fluid.

26. The method according to any one of claims 1 to 25, wherein the working electrode is a wire, a needle, or a microneedle.

27. The method according to any one of claims 1 to 26, wherein the electrochemical sensor includes a recognition element configured to specifically recognize a target analyte.

28. The method according to claim 27, wherein the recognition element is associated with a redox reporter.

29. The method according to claim 27 or 28, wherein the recognition element and / or the redox reporter undergoes a change in the presence of the target analyte, the change altering the rate of electron transfer between the redox reporter and the surface of the working electrode.

30. The method according to claim 29, wherein the change in the recognition element is a conformational change.

31. The method according to claim 30, wherein the conformational change in the recognition element alters the distance between the redox reporter and the surface of the working electrode.

32. The method according to claim 30 or 31, wherein the conformational change in the recognition element modifies the reorganization energy of the redox reporter.

33. The method according to any one of claims 28 to 32, wherein the speed at which the redox reporter approaches the surface of the working electrode is modified in the presence of the target analyte.

34. The method according to any one of claims 28 to 33, wherein, in the presence of the target analyte, the proportion of time the redox reporter is more proximal than distal to the surface of the working electrode is modified.

35. The method according to claim 33 or 34, wherein the modification of the rate of speed or time relates to a modification of the target analyte related to the stereovolumetric parameter, biomolecular rigidity parameter, electrostatic parameter, or hydrodynamic radius of the redox reporter.

36. The method according to any one of claims 29 to 35, wherein the change in the recognition element and / or the redox reporter is the dissociation of the recognition element from the target analyte.

37. The method according to any one of claims 30 to 36, wherein the conformational change modifies the rate of electron transfer between the redox reporter associated with the recognition element and the surface of the working electrode.

38. The method according to any one of claims 27 to 37, wherein the recognition element is associated with the surface of the work electrode, the redox reporter is associated with the recognition element, and the conformational change in the recognition element alters the distance between the redox reporter and the surface of the work electrode, which in turn alters the rate of electron transfer between the redox reporter and the surface of the work electrode.

39. The method according to any one of claims 27 to 38, wherein the recognition element is a biological polymer.

40. The method according to claim 39, wherein the biological polymer is a nucleic acid.

41. The method according to claim 39 or 40, wherein the biological polymer is an aptamer.

42. The method according to any one of claims 1 to 41, wherein the electrochemical sensor is configured as a wearable device.

43. An apparatus for determining the amount of analyte in a test sample: An electrochemical sensor having a working electrode and a counter electrode; A power supply configured to apply a voltage perturbation to the working electrode, wherein the voltage perturbation is the sum of two or more sinusoidal waveforms, and each of the two or more sinusoidal waveforms has a different frequency; A voltage and / or current measuring circuit connected across the working electrode and the counter electrode; A processor configured to integral-transform the measured voltage and / or current to produce an impedance spectrum, and to use the impedance spectrum to determine the amount of analyte in the test sample. The apparatus, including the above.

44. The apparatus according to claim 43, wherein the processor has access to program instructions configured to perform the method described in any one of claims 1 to 42.

45. The apparatus according to claim 43 or 44, wherein the electrochemical sensor includes a redox reporter, and the processor has access to program instructions configured to perform the method of claim 4 or 5.

46. The apparatus according to any one of claims 43 to 45, wherein the working electrode is a wire, a needle, or a microneedle.

47. The apparatus according to any one of claims 43 to 46, wherein the electrochemical sensor includes a recognition element configured to specifically recognize a target analyte.

48. The apparatus according to claim 47, wherein the recognition element is associated with a redox reporter.

49. The apparatus according to claim 47 or 48, wherein the recognition element and / or the redox reporter undergoes a change in the presence of the target analyte, and the change alters the rate of electron transfer between the redox reporter and the surface of the working electrode.

50. The apparatus according to claim 49, wherein the change in the recognition element is a conformational change.

51. The apparatus according to claim 50, wherein the conformational change in the recognition element modifies a coupling constant that describes the distance between the redox reporter and the surface of the working electrode or electron transfer through the recognition element.

52. The apparatus according to claim 50 or claim 51, wherein the conformational change in the recognition element modifies the reorganization energy of the redox reporter.

53. The apparatus according to any one of claims 48 to 52, wherein, in the presence of the target analyte, the rate at which the redox reporter approaches the surface of the working electrode or the rate of time over which it approaches is modified.

54. The apparatus according to any one of claims 48 to 53, wherein, in the presence of the target analyte, the proportion of time the redox reporter is more proximal than distal to the surface of the working electrode is modified.

55. The apparatus according to any one of claims 49 to 54, wherein the modification of the rate of speed or time relates to a modification of the target analyte in the stereovolumetric parameter, biomolecular rigidity parameter, electrostatic parameter, or hydrodynamic radius of the redox reporter.

56. The apparatus according to any one of claims 49 to 55, wherein the change in the recognition element and / or the redox reporter is the dissociation of the recognition element from the target analyte.

57. The apparatus according to any one of claims 50 to 56, wherein the conformational change in the recognition element modifies the rate of electron transfer between the redox reporter associated with the recognition element and the surface of the working electrode.

58. The apparatus according to any one of claims 47 to 57, wherein the recognition element is associated with the surface of the working electrode, the redox reporter is associated with the recognition element, and the conformational change in the recognition element alters the distance between the redox reporter and the surface of the working electrode, which in turn alters the rate of electron transfer between the redox reporter and the surface of the working electrode.

59. The apparatus according to any one of claims 47 to 58, wherein the recognition element is a biological or biomimetic polymer.

60. The apparatus according to claim 59, wherein the biological polymer is a nucleic acid.

61. The apparatus according to claim 59 or 60, wherein the biological polymer is an aptamer.

62. The apparatus according to any one of claims 43 to 61, wherein the electrochemical sensor is configured as a wearable device.

63. A non-temporary computer-readable medium comprising computer executable program instructions configured to perform the method described in any one of claims 1 to 42.

64. The apparatus according to any one of claims 43 to 62, wherein the program instructions are provided by a non-temporary computer-readable medium as described in claim 63.

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