Nanopore Size Estimation by Electrochemical Impedance Spectroscopy Analysis

We present a simple and cost-effective approach by electrochemical impedance spectroscopy (EIS) for the accurate pore size estimation of silicon based nanopores. This method takes into account the capacitor effects of the electrical double layer and the resistor effects of the ion concentration inside the nanochannel. The nanopore impedance was modeled as the electrolyte resistance Rs in series with a parallel ion diffusion circuit charge transfer resistance Rf with a constant phase element (CPE) that models the behavior of the double layer. EIS analysis, which has been widely employed to measure the energy storage and dissipation properties of physico-chemical systems in a frequency domain, was adopted to obtain the impedance parameters of the nanopores. The nanopore size was then estimated from the impedance parameters. The accuracy of the estimated nanopore size was verified using an transmission electron microscope (TEM) image.