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Capacitance detection in electrochemical assay

  • US 9,645,104 B2
  • Filed: 04/07/2014
  • Issued: 05/09/2017
  • Est. Priority Date: 02/25/2010
  • Status: Expired due to Fees
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

    )|÷



    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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