Capacitance detection in electrochemical assay
First Claim
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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:
- initiating an electrochemical reaction in the biosensor chamber;
applying an oscillating voltage of a predetermined frequency to the chamber;
determining a phase angle between a current output and the oscillating voltage from the chamber; and
calculating a capacitance of the chamber based on a product of the current output and a sine of the phase angle divided by a product of two times pi times the frequency and the voltage, and wherein the calculating comprises calculating capacitance with an equation of the form;
C=|(iT sin Φ
)|÷
2π
fV where;
C≈
capacitance;
iT≈
total current;
Φ
≈
phase angle between total current and resistor current;
f≈
frequency; and
V≈
voltageand in which the calculating further comprises;
sampling a plurality of current outputs from the chamber over one cycle of the frequency;
obtaining a mean of sampled current output;
subtracting the mean from each sampled current of the plurality of current outputs; and
extracting root-mean-squared value of all negative values from the subtracting to provide for the total current output.
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Abstract
A method and system are provided to determine fill sufficiency of a biosensor test chamber by determining capacitance of the test chamber in which an electrochemical reaction is initiated in the test chamber and an oscillating voltage of a predetermined frequency is applied to the chamber. A phase angle between a current output and the oscillating voltage from the chamber is determined and the capacitance is calculated based on a product of the current output and a sine of the phase angle divided by a product of two times pi times the frequency and the voltage.
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Citations
5 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 in the biosensor chamber; applying an oscillating voltage of a predetermined frequency to the chamber; determining a phase angle between a current output and the oscillating voltage from the chamber; and calculating a capacitance of the chamber based on a product of the current output and a sine of the phase angle divided by a product of two times pi times the frequency and the voltage, and wherein the calculating comprises calculating capacitance with an equation of the form;
C=|(iT sin Φ
)|÷
2π
fVwhere; C≈
capacitance;iT≈
total current;Φ
≈
phase angle between total current and resistor current;f≈
frequency; andV≈
voltageand in which the calculating further comprises; sampling a plurality of current outputs from the chamber over one cycle of the frequency; obtaining a mean of sampled current output; subtracting the mean from each sampled current of the plurality of current outputs; and extracting root-mean-squared value of all negative values from the subtracting to provide for the total current output. - View Dependent Claims (2, 3, 4, 5)
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Specification