Method for Determination of Analyte Concentrations and Related Apparatus
First Claim
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1. A method for determining an analyte in a sample comprising the steps of:
- introducing a sample to be evaluated into an electrochemical test strip having working and counter electrodes;
applying a potential between the electrodes sufficient to generate a diffusion-limited current when analyte is present in the sample;
dynamically determining a time, tpeak, as the time when diffusion limiting current at the counter electrode is established;
sampling the current value at a time, tmeas, wherein tmeas is after tpeak, and tmeas is determined based on the value of tpeak, and generating an indication of analyte in the sample based on the sampled current value at time tmeas.
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Abstract
A method is provided for determining analyte concentrations, for example glucose concentrations, that utilizes a dynamic determination of the appropriate time for making a glucose measurement, for example when a current versus time curve substantially conforms to a Cottrell decay, or when the current is established in a plateau region. Dynamic determination of the time to take the measurement allows each strip to operate in the shortest appropriate time frame, thereby avoiding using an average measurement time that may be longer than necessary for some strips and too short for others.
169 Citations
27 Claims
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1. A method for determining an analyte in a sample comprising the steps of:
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introducing a sample to be evaluated into an electrochemical test strip having working and counter electrodes;
applying a potential between the electrodes sufficient to generate a diffusion-limited current when analyte is present in the sample;
dynamically determining a time, tpeak, as the time when diffusion limiting current at the counter electrode is established;
sampling the current value at a time, tmeas, wherein tmeas is after tpeak, and tmeas is determined based on the value of tpeak, and generating an indication of analyte in the sample based on the sampled current value at time tmeas. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A meter for receiving an electrochemical test strip having electrodes and providing a determination of an analyte in a sample applied to the electrochemical test strip when received in the meter, said meter comprising
(a) a housing having a slot for receiving an electrochemical test strip; -
(b) communications means for receiving input from and communicating a result to a user;
(c) means for determining a time, tpeak, as the time when diffusion limiting current at the counter electrode is established and dynamically determining tmeas based upon the determined value of tpeak wherein tmeas is after tpeak, and tmeas is determined based on the value of tpeak;
(d) means for evaluating current at tmeas to generate a determination of analyte. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A method for determining the time of sample application, and triggering the start of an electrochemical assay conducted in an electrochemical test cell comprising a working and a counter electrode, comprising the steps of:
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(a) applying a pulsed voltage, Vw, to the working electrode while holding the voltage, Vc, of the counter electrode constant commencing at a time prior to the introduction of sample to the electrochemical test cell, said pulsed voltage having a pulse frequency;
(b) monitoring the electrochemical test cell for the passage of current between the electrodes, said passage of current being in the form of current spikes having a frequency equal to the pulse frequency and being indicative of the addition of a sample to the electrochemical test cell, and (c) triggering the start of the electrochemical assay when a plurality of current spikes have been observed, and when said plurality is least a pre-determined fraction of the pre-determined number of consecutive current spikes. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26)
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27. A method for detecting an error condition in an electrochemical determination of an analyte in a sample applied to an electrochemical test strip disposed in an analyte detection apparatus, comprising the steps of:
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(a) introducing a sample to be evaluated into an electrochemical test strip having working and counter electrodes;
(b) applying a potential between the electrodes sufficient to generate a diffusion-limited current when analyte is present in the sample;
(c) dynamically determining a time, tpeak, as the time when diffusion limiting current at the counter electrode is established;
(d) comparing the determined value of tpeak to a predetermined range, and returning an error message when the determined value falls outside of the range.
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Specification