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Detection circuitry for electrochemical analysis

  • US 4,426,621 A
  • Filed: 06/29/1981
  • Issued: 01/17/1984
  • Est. Priority Date: 06/29/1981
  • Status: Expired due to Fees
First Claim
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1. In combination, an electrochemical cell having a receptacle for electrolyte, electrodes arranged in said electrolyte including:

  • a counter electrode, a reference electrode, and two working electrodes;

    a pair of test signal input terminals, one of which is connected to a fixed reference potential;

    an input differential amplifier circuit having an output connected to said counter electrode, one input connected to said reference electrode, and another input connected to said other test signal input terminal;

    a signal detection circuit including;

    first and second differential amplifying circuits each having a first input terminal, a second input terminal and an output terminal;

    an output differential amplifier having a pair of input terminals and an output terminal;

    means connecting the output terminals of said first and second amplifying circuits to a different one of said pair of input terminals of said output differential amplifier;

    means connecting said first input terminal of each said first and second differential amplifying circuit to a different said working electrode;

    means connecting said second input terminal of one of said first and second amplifying circuits to said reference potential; and

    means, including a potentiometer, for connecting said second input terminal of the other of said first and second differential amplifying circuits and the other input terminal of said pair of input terminals of said output differential amplifier to said reference potential whereby the signals supplied to said output differential amplifier may be varied relative to each other by said potentiometer independently of the currents supplied to said first and second amplifying circuits from said respective working electrodes when said test signal is applied to said test signal input terminals to permit detecting any difference in currents passing between said electrolyte and said working electrodes, which difference represents a characteristic of an electroactive species in a test sample added to said electrolyte.

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