Capacitance detection in electrochemical assay with improved sampling time offset
First Claim
1. A method of determining capacitance of a biosensor chamber having two electrodes disposed in the chamber and coupled to a microcontroller, the method comprising:
- initiating an electrochemical reaction of a sample upon deposition of the sample in the biosensor chamber;
applying an oscillating signal of a predetermined frequency to the chamber;
ascertaining a first sampling-time interval for measurement of an output signal based on a predetermined sampling rate per cycle of the output signal at the predetermined frequency;
sampling the output signal from the chamber at a second sampling-time interval different than the first sampling-time interval such that a magnitude of each sampled output signal is measured at each succession of the second sampling-time interval instead of at the first time interval;
determining a phase angle between an output signal and the oscillating input signal from the chamber based on the sampled output signal of the sampling step; and
calculating a capacitance of the chamber from the phase angle.
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Abstract
A method and a system are provided to determine fill sufficiency of an electrochemical biosensor test cell by determining capacitance of the electrochemical test cell. In particular, the system samples an output signal from the chamber at a second sampling-time interval different than a first sampling-time interval such that a magnitude of each sampled output signal is measured at each succession of the second sampling-time interval instead of at the first time interval. The system determines a phase angle between an output signal and the oscillating input signal from the chamber based on the sampled output signal of the sampling step. The system calculates a capacitance of the chamber from the phase angle. A method is also provided to perform similar functionalities of the system.
19 Citations
23 Claims
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1. A method of determining capacitance of a biosensor chamber having two electrodes disposed in the chamber and coupled to a microcontroller, the method comprising:
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initiating an electrochemical reaction of a sample upon deposition of the sample in the biosensor chamber; applying an oscillating signal of a predetermined frequency to the chamber; ascertaining a first sampling-time interval for measurement of an output signal based on a predetermined sampling rate per cycle of the output signal at the predetermined frequency; sampling the output signal from the chamber at a second sampling-time interval different than the first sampling-time interval such that a magnitude of each sampled output signal is measured at each succession of the second sampling-time interval instead of at the first time interval; determining a phase angle between an output signal and the oscillating input signal from the chamber based on the sampled output signal of the sampling step; and calculating a capacitance of the chamber from the phase angle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. An analyte measurement system comprising:
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An analyte test strip including; a substrate having a reagent disposed thereon; at least two electrodes proximate the reagent a in test chamber of the test strip; an analyte meter including; a strip port connector disposed to connect to the two electrodes; a power supply; and a microcontroller electrically coupled to the strip port connector and the power supply, the microcontroller being programmed to; (a) initiate an electrochemical reaction in the biosensor chamber;
apply an oscillating voltage of a predetermined frequency to the chamber;(b) ascertain a first sampling-time interval for measurement of an output signal based on a predetermined sampling rate per cycle of the output signal at the predetermined frequency; (c) sample the output signal from the chamber at a second sampling-time interval different than the first sampling-time interval such that a magnitude of each sampled output signal is measured at each succession of the second sampling-time interval instead of at the first time interval; (d) determine a phase angle between a current output and the oscillating voltage from the chamber based on the sampled output signal; and (e) calculate a capacitance of the chamber based on the determined phase angle. - View Dependent Claims (20, 21, 22, 23)
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Specification