Optimization of the perturbation signal for electrochemical impedance spectroscopy in the time domain

Abstract

The choice of the perturbation wave form is of crucial importance for reliable electrochemical impedance spectroscopy measurements based on the fast Fourier transformation. Using numerical simulation, arguments and results are presented for the choice and the optimization of a perturbation signal constructed as a superposition of discrete sine waves with selected frequencies. Two possible ways to optimize the perturbation for better noise immunity are described: choosing proper values for the phases of the individual sine waves, minimal perturbation signal amplitudes can be obtained which improve the quality of impedance data by 25%. By introducing response-sensitive amplitudes an improvement in the quality of data by a factor of 4–5 can be reached in the low frequency range. A new technique for single-pulse measurements with continuous perturbations that assures a steady-state response and better accuracy at high capacitive and/or inductive samples is also described.