Interdigitated electrode (IDE) arrays have been used widely for electrochemical impedance spectroscopy (EIS). Here, we present an in-depth analysis of interdigitated electrode impedance spectra. Such an analysis is necessary for the identification of the contribution of each interdigitated electrode circuit element to the impedance change. We also discuss the importance of the solution conductivity in impedance spectroscopy showing that the use of low conductivity solutions is advantageous when inter-digit solution resistance and geometric capacitance need to be monitored. (C) 2011 Elsevier Ltd. All rights reserved.