Voltammetric and amperometric transducers

Abstract

A voltammetric measurement is made when the potential difference across an electrochemical cell is scanned from one preset value to another, and the cell current is recorded as a function of the applied potential. The curve so generated is known as a voltammogram. Amperometric measurements are made by recording the current flow in the cell at a single applied potential. At first sight transducers based on voltammetric and amperometric principles appear to be near-ideal devices for probing the selective chemistry of a sensor. In both cases, the essential operational feature of such a transducer is the transfer of an electron or electrons to or from the probed chemistry. It is the flow of these electrons that constitutes the output signal of the transducer. Additionally, voltammetric and amperometric devices are capable of conferring a degree of selectivity to the overall sensing process. This arises from the dependence of the measured current on the applied potential, a dependence that, to some extent, is a function of the standard potential of the redox couple under study. Voltammetric and amperometric transducers are also relatively simple: in the most elementary case, the transducer (electrochemical cell) consists of two electrodes immersed in a suitable electrolyte. A more complex arrangement involves the use of a three-electrode cell, one of the electrodes providing a reference potential.