Systems and methods for hematocrit impedance measurement using switched capacitor accumulator
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Publication Number
US-11723561-B2
Publication Date
2023-08-15
Expiration Date
Abstract
There is provided a system for measuring a property of a sample that comprises a test strip for collecting the sample; a diagnostic measuring device configured to receive the test strip and measure a concentration of an analyte in the sample received on the test strip; and the diagnostic measuring device further comprising a processor programmed to execute an analyte correction for correcting a measurement of the sample due to one or more interferents, comprising: calculating an interferent impedance measurement including a magnitude measurement and a phase measurement using a switched capacitor accumulator to measure a phase angle; and adjusting the measurement of the analyte in the sample using that the calculated interferent impedance measurement.
Core Innovation
A handheld blood glucose/hemoglobin system determines hematocrit (HCT) by measuring hematocrit impedance using excitation in the range of 10 kHz to 500 kHz. The hematocrit impedance is used as an interferent input to correct glucose measurements for interferent effects, and the impedance measurement supports both a magnitude measurement and a phase measurement, enabling complex impedance measurement including magnitude and phase.
The phase measurement is obtained by measuring time differences using a switched capacitor accumulator within a sample window of multiple setpoints of frequency in the range of 10 kHz to 500 kHz, and accumulating the time differences over the sample window to generate a signal large enough to be measured for calculating the phase measurement. The system also measures magnitude using comparator-based peak detection of excitation voltage and response current.
The processor executes an analyte correction by adjusting the analyte measurement using the calculated interferent impedance measurement. The document describes impedance/phase-to-reactance relationships and example glucose correction algorithms that scale or subtract interference currents, and incorporate temperature-corrected HCT, including a temperature correction referenced to dT/24°C.
Claims Coverage
The independent claims cover measuring an analyte concentration and executing an analyte correction due to one or more interferents by calculating an interferent impedance measurement that includes magnitude and phase. Across the independent claims, the inventive core includes phase measurement using a switched capacitor accumulator with time differences accumulated over a sample window using multiple frequency setpoints in the range of 10 kHz to 500 kHz, and using the calculated interferent impedance to adjust the analyte measurement.
Analyte correction using interferent impedance measurement with magnitude and phase
A diagnostic measuring device receives a test strip and measures an analyte concentration, and executes an analyte correction for correcting the measurement due to one or more interferents by calculating an interferent impedance measurement including a magnitude measurement and a phase measurement, and adjusting the measurement of the analyte using the calculated interferent impedance measurement.
Phase angle measurement by time differences accumulated over a frequency setpoint window using a switched capacitor accumulator
Measuring the phase angle comprises measuring time differences using the switched capacitor accumulator within a sample window of multiple setpoints of frequency in the range of 10 kHz to 500 kHz, and accumulating the time differences that represent phase over the sample window to generate a signal large enough to be measured to calculate the phase measurement.
Method of measuring and correcting analyte concentration using interferent impedance
A method measures an analyte in a sample, performs an analyte correction due to one or more interferents by calculating an interferent impedance measurement including a magnitude measurement and a phase measurement using a switched capacitor accumulator, and adjusting the measurement of the analyte in the sample using the calculated interferent impedance measurement.
The independent claims consistently tie interferent-aware analyte correction to a calculated interferent impedance measurement with magnitude and phase, where the phase measurement is performed by accumulating time differences from a switched capacitor accumulator over a sample window using multiple frequency setpoints in the 10 kHz to 500 kHz range.
Stated Advantages
Enables interferent impedance-based correction of glucose measurements for interferent effects using hematocrit impedance.
Supports complex impedance measurement including magnitude and phase using low-power circuitry.
Documented Applications
Handheld blood glucose/hemoglobin system that determines hematocrit (HCT) by measuring hematocrit impedance and uses the result to correct glucose measurements.
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