Analyte determination method and analyte meter
Inventors
Harding, Ian • Williams, Richard • Iyengar, Sridhar
Assignees
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Publication Number
US-10641725-B2
Publication Date
2020-05-05
Expiration Date
Abstract
The presence of oxygen or red blood cells in a sample applied to an electrochemical test strip that makes use of a reduced mediator is corrected for by an additive correction factor that is determined as a function of the temperature of the sample and a measurement that reflects the oxygen carrying capacity of the sample. The measured oxygen carrying capacity can also be used to determine hematocrit and to distinguish between blood samples and control solutions applied to a test strip.
Core Innovation
The disclosed invention relates to electrochemical determination of an analyte in a sample using an electrochemical test cell with a working and a counter electrode and a mediator that serves as a charge carrier. An uncorrected result for the analyte is determined electrochemically, and the uncorrected result is modified by adding an additive correction term to provide a corrected determination of analyte in the sample. The additive correction term is determined for the amount of oxygen in the sample.
The additive correction term is determined as a function of the temperature of the sample and a measurement that reflects the oxygen carrying capacity of the sample. The oxygen carrying-capacity reflecting measurement is determined by applying a potential for a period of time sufficient to establish a chemical potential gradient between the electrodes, switching off the applied potential at a time t_switch, and obtaining a value indicative of the rate of decay of the chemical potential gradient in the absence of applied potential.
The disclosed approach is also described as using the oxygen-carrying-capacity decay metric, optionally with temperature, for hematocrit determination and for distinguishing blood samples from control solutions. The patent further describes a meter/test-strip architecture that includes switching between amperometric and potentiometric modes and using the decay metric derived from the chemical potential gradient decay behavior.
Claims Coverage
The partial content provides two independent claims. Across these, the inventive features are (i) oxygen-based additive correction of an electrochemical analyte result using a temperature-dependent model and an oxygen-carrying-capacity measurement derived from chemical-potential-gradient decay, and (ii) a meter that implements this correction workflow using a programmed microprocessor receiving an electrochemical test strip and using the same decay-rate measurement concept.
Oxygen additive correction term for uncorrected analyte results
Determining an uncorrected result for the determination of analyte in the sample and modifying the uncorrected result by adding an additive correction term for the amount of oxygen in the sample to provide a corrected determination.
Temperature- and oxygen-carrying-capacity dependent oxygen correction
Determining the additive correction term for the amount of oxygen in the sample as a function of the temperature of the sample and a measurement that reflects the oxygen carrying capacity of the sample.
Chemical potential gradient decay measurement without applied potential
Determining the oxygen-carrying-capacity reflecting measurement by applying a potential for a period of time sufficient to establish a chemical potential gradient between the electrodes, switching off the applied potential at a time t_switch, and obtaining a value indicative of the rate of decay of the chemical potential gradient in the absence of applied potential.
Meter implementing oxygen correction from test strip decay-rate measurement
Providing a meter that receives an electrochemical test strip and determines an uncorrected result for the determination of analyte in the sample, determines an additive correction term for the amount of oxygen in the sample, and modifies the uncorrected result by adding the additive correction term to provide a corrected determination, where the additive correction term is determined as a function of the temperature of the sample and a measurement reflecting the oxygen carrying capacity obtained from chemical potential gradient decay without applied potential (using t_switch).
In both independent claims, the core claim coverage centers on correcting an electrochemical analyte determination with an oxygen-dependent additive correction term computed from a temperature-dependent oxygen-carrying-capacity measurement derived from chemical potential gradient decay after switching off an applied potential at time t_switch. The second independent claim further places this functionality in a meter with a programmed microprocessor receiving a test strip and performing the same correction workflow.
Stated Advantages
Provides a corrected determination of analyte by modifying an uncorrected electrochemical result using an additive correction term for oxygen.
Enables oxygen-related interference correction using a measurement reflecting oxygen carrying capacity determined from chemical potential gradient decay, with temperature dependence.
Supports determination of hematocrit using the decay metric, optionally with temperature.
Helps distinguish blood samples from control solutions using the decay metric.
Documented Applications
Electrochemical determination of an analyte such as glucose in a sample using an electrochemical test strip/test cell and an oxygen additive correction term.
Hematocrit determination using the oxygen-carrying-capacity decay metric, optionally with temperature.
Distinguishing blood samples from control solutions using the decay metric derived from chemical potential gradient decay.
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