Gated amperometry methods
First Claim
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1. A method of reducing bias attributable to mediator background in a determined concentration of an analyte in a sample comprising:
- generating a measurable species from a mediator, the concentration of the measurable species responsive to a concentration of an analyte in a sample;
applying an input signal to the sample, the input signal comprising at least 3 duty cycles within 180 seconds and each duty cycle comprising an excitation and a relaxation,where the input signal has a redox intensity of at least 0.01 if continued for a 10 second duration,where the relaxations of the at least 3 duty cycles each provide an independent diffusion and analyte reaction time during which the analyte generates the measurable species;
measuring an output signal from at least one amperometric excitation of the at least 3 duty cycles,the output signal responsive to the concentration of the measurable species in the sample, andthe at least one amperometric excitation having a duration from 0.01 second to 1.5 seconds; and
determining the concentration of the analyte in the sample having reduced bias attributable to mediator background in response to the measured output signal, where the determined concentration is responsive to a rate at which the measurable species is oxidized or reduced by the input signal.
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Abstract
A sensor system, device, and methods for determining the concentration of an analyte in a sample is described. Gated amperometric 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 gated amperometric pulse sequences may reduce analysis errors arising from the hematocrit effect, variance in cap-gap volumes, non-steady-state conditions, mediator background, under-fill, temperature changes in the sample, and a single set of calibration constants.
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Citations
57 Claims
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1. A method of reducing bias attributable to mediator background in a determined concentration of an analyte in a sample comprising:
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generating a measurable species from a mediator, the concentration of the measurable species responsive to a concentration of an analyte in a sample; applying an input signal to the sample, the input signal comprising at least 3 duty cycles within 180 seconds and each duty cycle comprising an excitation and a relaxation, where the input signal has a redox intensity of at least 0.01 if continued for a 10 second duration, where the relaxations of the at least 3 duty cycles each provide an independent diffusion and analyte reaction time during which the analyte generates the measurable species; measuring an output signal from at least one amperometric excitation of the at least 3 duty cycles, the output signal responsive to the concentration of the measurable species in the sample, and the at least one amperometric excitation having a duration from 0.01 second to 1.5 seconds; and determining the concentration of the analyte in the sample having reduced bias attributable to mediator background in response to the measured output signal, where the determined concentration is responsive to a rate at which the measurable species is oxidized or reduced by the input signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A method of signaling a user to add additional sample to a sensor strip, comprising:
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applying an input signal to a sample contacting working and counter electrodes of a sensor strip, the input signal including at least 3 duty cycles within 180 seconds and each duty cycle comprising an excitation and a relaxation; measuring an output signal including currents from the excitations of at least two of the at least 3 duty cycles; determining a decay constant profile from the measured output signal for the at least two excitations; determining if the sensor strip is under-filled from the decay constant profiles determined from the at least two excitations; signaling the user to add additional sample to the sensor strip when the sensor strip is under-filled; and determining a concentration of an analyte in the sample from the output signal. - View Dependent Claims (28, 29, 30, 31, 32)
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33. A method of determining the temperature of a sample contained by a sensor strip, comprising:
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previously determining correlations between decay rate and temperature; determining a current profile from currents recorded during at least two excitations of an input signal including at least 3 duty cycles within 180 seconds; correlating the current profile to the correlations between decay rate and temperature to determine the temperature of the sample. - View Dependent Claims (34, 35, 36, 37)
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38. A method of determining the duration of an input signal to apply to a sample, for determining the concentration of an analyte in the sample, the method comprising:
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previously determining multiple sets of calibration constants from currents recorded at fixed times from an output signal; applying an input signal including at least 3 duty cycles within 180 seconds to the sample, where each of the at least 3 duty cycles includes an excitation; and determining a concentration of the analyte in the sample from an output signal measured from the excitation of at least one of the at least 3 duty cycles; determining the duration of the input signal to apply to the sample in response to the determined concentration of the analyte in the sample. - View Dependent Claims (39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49)
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50. A handheld measuring device, for determining the concentration of an analyte in a sample, where
the device is capable of receiving a sensor strip and the device comprises: -
contacts; at least one display; and electrical circuitry establishing electrical communication between the contacts and the display, the circuitry comprising; an electric charger and a processor in electrical communication, the processor in electrical communication with a non-transitory computer readable storage medium comprising computer readable software code, which when executed by the processor, the processor is capable of causing the charger to implement an input signal comprising at least 3 duty cycles within 180 seconds between the contacts, each duty cycle comprising an excitation and a relaxation;
wherethe input signal has a redox intensity of at least 0.01 if continued for a 10 second duration of the input signal; the processor is capable of measuring the output signal from an amperometric excitation of the at least 3 duty cycles, the amperometric excitation having a duration from 0.01 to 1.5 seconds, where the amperometric excitation follows a relaxation providing an independent diffusion and analyte reaction time during which the analyte generates measurable species, the relaxation provided by an open circuit; and the processor is capable of determining an analyte concentration of a sample from the measured output signal, where the determined concentration is responsive to a rate at which the measurable species is oxidized or reduced by the input signal. - View Dependent Claims (51, 52, 53, 54, 55, 56, 57)
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Specification