Abstract: An electrochemical instrument for use with an electrochemical cell that provides IR compensation while operating as either a galvanostat or a potentiostat. The instrument includes an electronic circuit having two output terminals, an input differential amplifier circuit, an output differential amplifier circuit, a control differential amplifier circuit, a reference differential amplifier circuit, a resistor, electric circuitry connecting the input terminal of the control amplifier to the instrument output terminal and a double pole, double throw switch means. In a preferred embodiment, the electric circuitry connecting the control amplifier to the instrument output terminal is a potentiometer.

Abstract: An electronic circuit arrangement effecting current flow simulating the faradaic current, oxidation reduction potential and the like of an electrochemical cell encompasses two key concepts. The first recognizes that since the semi-integral of the cell current effectively deconvolves the diffusion aspect of the phenomenon with the resultant describing the surface concentration of reacted species, then the semiderivative of a function describing a surface concentration of reacted species results in an output representing the cell current, including diffusion. The second is embodied in a circuit arrangement properly simulating this concentration behavior cell double layer potential and in yielding an output proportional to the surface concentration of reactant species corresponding to that potential in response to applied cell barrier potential.

Abstract: An improved instrument for use with an electrochemical cell that provides a system having enhanced stability and increased bandwidth. The instrument includes a voltage to current converter which drives the cell. The current output of the voltage to current converter is linearly proportional to the differential voltage input. The voltage to current converter drives the cell in both the potentiostatic mode and in the galvanostatic mode of operation.

Abstract: Analytical apparatus is arranged for increased sensitivity in determining a desired characteristic by decreasing the sensitivity to extraneous noise, essentially as common mode signal, while treating the desired signal differentially. Test signal is applied to apparatus comprising an electrochemical cell containing electrolyte in which a pair of matched working electrodes are equispaced from a counter electrode and from a reference electrode. The working electrodes conduct different values of current, the difference being a measure of characteristic of material making up the electrolyte. The signal applied between the counter and the working electrodes is varied over a predetermined range. The potential between the working electrodes is established at zero for basic operation, but a fixed biasing potential is established between the two working electrodes for a given experiment in which the test signal is varied.

Abstract: The control of the operation of an electric circuit element, such as an electrochemical cell, is performed by positive feedback servocircuitry developing an error signal or inherent noise component, and having algebraic computing capability for developing the compensating control. Current follower circuitry is arranged for developing a potential proportional to the current drawn by the electric circuit element to be controlled. A portion of this potential is algebraically combined with the externally applied operating electric wave. The inherent noise component of the control circuitry is sensed by a high pass filter and an ac-dc converting circuit and thereafter integrated for generating a slowly varying potential for determining the portion of the potential derived by sensing the current. The two potentials are applied to a conventional multiplying circuit and the product potential combined with the operating wave.

Abstract: An improved potentiostat for use with electrochemical cells provides dynamic protection of both the electrochemical cell elements and the sensitive potentiostat components from any significant voltage or current overload. A comparator compares the potentiostat input voltage with the electrochemical cell reference electrode voltage. When the reference electrode voltage becomes substantially different from the potentiostat input voltage and exceeds a certain preset value, the comparator activates a control means that causes the cell current to go to zero. This system provides dynamic protection even as the input voltage varies.