Some factors in potentiostat design

Abstract The factors controlling the design of potentiostats are discussed. The frequency dependence of the phase shift and amplitude of the signals at the reference electrode are deduced for various models of the Luggin capillary. The theoretical results are compared to experimental data over a wide frequency range and the frequency dependence of the feedback fraction is deduced; the restrictions the cell design imposes on the electrical performance of a potentiostat are discussed. The design of a potentiostat, unconditionally stable for all electrode reactions, is described. Particular emphasis is placed on the phase- frequency relationship and the design of the input and output stages. The potentiostat has a medium sensitivity and wide bandwidth and the performance is analysed and compared to that of other instruments. The application of the potentiostat to various types of measurement is described.