Simultaneous Electrochemical and Mechanical Impedance Spectroscopy Using Cantilever Curvature

Abstract

Electrochemical impedance spectroscopy is applied to in-situ stress measurements of a gold cantilever electrode in 0.1 mol/L HClO4 as a new technique for studying stress phenomena in thin films. The resonant frequency of the cantilever is found to be inversely proportional to the square of its length as predicted by theory. In the double layer region, a linear response both electrochemically and mechanically is achieved for input signal amplitudes up to 80 mV. For frequencies below the resonant frequency of the cantilever (∼20 Hz), the surface stress and the charge are out of phase and the amplitude of the surface stress response f0 varies linearly with the amplitude of the charge density q0. A maximal value for f0/q0 of 2 V is obtained in the double layer region in good agreement with experimental and calculated values reported in the literature.