Gated voltammetry methods
First Claim
1. A method of signaling a user to add additional sample to a sensor strip, the sensor strip including at least two electrodes, the method comprising:
- applying a gated voltammetric pulse sequence to the sample through the at least two electrodes of the sensor strip, the pulse sequence having at least two duty cycles,wherein each of the at least two duty cycles includes an excitation and a relaxation, andwherein the excitations of the at least two duty cycles include a potential varied with time and the relaxations of the at least two duty cycles include a current reduction to at least one-half the current flow at the excitation maxima;
determining if the sensor strip is under-filled by comparing at least one current value recorded from the gated voltammetric pulse sequence including the at least two duty cycles to a pre-selected value; and
signaling the user to add additional sample to the sensor strip if the sensor strip is under-filled.
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Accused Products
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.
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Citations
31 Claims
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1. A method of signaling a user to add additional sample to a sensor strip, the sensor strip including at least two electrodes, the method comprising:
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applying a gated voltammetric pulse sequence to the sample through the at least two electrodes of the sensor strip, the pulse sequence having at least two duty cycles, wherein each of the at least two duty cycles includes an excitation and a relaxation, and wherein the excitations of the at least two duty cycles include a potential varied with time and the relaxations of the at least two duty cycles include a current reduction to at least one-half the current flow at the excitation maxima; determining if the sensor strip is under-filled by comparing at least one current value recorded from the gated voltammetric pulse sequence including the at least two duty cycles to a pre-selected value; and signaling the user to add additional sample to the sensor strip if the sensor strip is under-filled. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A voltammetric method for determining a concentration of an analyte in a sample, the voltammetric method comprising:
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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, wherein each of the at least two duty cycles includes a relaxation, and the relaxations of the at least two duty cycles include a current reduction to at least one-half the current flow at the excitation maxima; measuring resulting currents from the at least two duty cycles; and determining the concentration of the analyte in the sample from the resulting currents. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. A voltammetric method for determining a hematocrit concentration of a blood sample, the voltammetric method comprising:
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applying a gated voltammetric pulse sequence to the blood sample, the pulse sequence having at least two duty cycles, wherein each of the at least two duty cycles includes an excitation and a relaxation, and wherein the excitations of the at least two duty cycles include a potential varied with time and the relaxations of the at least two duty cycles include a current reduction to at least one-half the current flow at the excitation maxima; measuring resulting currents from at least one of the excitations; applying a semi-integral data treatment to the resulting currents, the semi-integral data treatment providing a peak portion; and quantitatively relating the peak portion to the hematocrit concentration of the blood sample. - View Dependent Claims (19, 20)
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21. A voltammetric method for determining a percent hematocrit of a blood sample, the voltammetric method comprising:
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applying a gated voltammetric pulse sequence to the blood sample, the pulse sequence having at least two duty cycles, wherein each of the at least two duty cycles includes an excitation and a relaxation, and wherein the excitations of the at least two duty cycles include a potential varied with time and the relaxations of the at least two duty cycles include a current reduction to at least one-half the current flow at the excitation maxima; measuring resulting currents from at least one of the excitations; applying a derivative data treatment to the resulting currents, the derivative data treatment providing a negative derivative peak and a positive derivative peak; determining a ratio of the negative derivative peak to the positive derivative peak; and quantitatively relating the ratio to the percent hematocrit in the blood sample. - View Dependent Claims (22, 23)
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24. A method of determining an amount of active ionizing agent available to react with an analyte, the method comprising:
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applying a gated voltammetric pulse sequence to a sample in a sensor strip through at least two electrodes, the pulse sequence having at least two duty cycles, the sample including an analyte and active ionizing agent, wherein each of the at least two duty cycles includes an excitation and a relaxation, wherein the excitations of the at least two duty cycles include a potential varied with time and the excitations include forward and reverse scans, and wherein the relaxations of the at least two duty cycles include a current reduction to at least one-half the current flow at the excitation maxima; measuring resulting currents from the forward and the reverse scans of at least one of the excitations; determining a ratio of the resulting currents from the forward and the reverse scans; comparing the determined ratio to a previously determined correlation ratio and a percent active ionizing agent; and determining the amount of the active ionizing agent available to react with the analyte. - View Dependent Claims (25, 26, 27, 28)
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29. A voltammetric method for determining a concentration of an analyte in a sample, the voltammetric method comprising:
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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, wherein each of the at least two duty cycles includes an excitation, and wherein the excitations comprise a potential varied linearly at a rate of at least 2 mV/sec; measuring resulting currents from the at least two duty cycles; and determining the concentration of the analyte in the sample from the resulting currents.
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30. A voltammetric method for determining a concentration of an analyte in a sample, the voltammetric method comprising:
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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, wherein each of the at least two duty cycles includes an excitation, and wherein the excitations are acyclic and substantially exclude a reverse oxidation peak or a reverse reduction peak of a measurable species responsive to the concentration of the analyte in the sample; measuring resulting currents from the at least two duty cycles; and determining the concentration of the analyte in the sample from the resulting currents.
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31. A voltammetric method for determining a concentration of an analyte in a sample, the voltammetric method comprising:
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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, wherein each of the at least two duty cycles includes an excitation; measuring resulting currents from the at least two duty cycles; and determining the concentration of the analyte in the sample from the resulting currents, wherein the excitations are acyclic and terminate before initiation of a reverse current peak, the excitations are acyclic and substantially exclude forward and reverse oxidation and reduction peaks of a measurable species responsive to the concentration of the analyte in the sample, or the excitations are acyclic and are substantially within a diffusion limited current region of a redox pair.
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Specification