Linear and nonlinear properties of platinum electrode polarisation II: time domain analysis

Abstract

The linear and nonlinear transient behaviour of a platinum electrode in physiological saline (0·9% NaCl) was investigated. The interface overpotential (current) in response to a step current (voltage) was monitored over six decades of pulse duration starting at 10 μs, both in the linear range, i.e. where the polarising current and the polarisation voltage are proportional, and in the nonlinear range, where this proportionality is lost. The time invariance of the Pt electrode/physiological saline interface parameters in the linear range and at the onset of nonlinearity over the studied band of frequencies and pulse durations is deduced from the equivalence of experimental results obtained in the frequency and time domains using the appropriate transformation when map** the two domains. We conclude that the interface can be analysed and modelled in either domain in the linear range and at the onset of nonlinearity.