Three-Dimensional Electrochemical Functionality of an Interdigitated Array Electrode by Scanning Electrochemical Microscopy

Abstract

As interdigitated array electrodes (IDAEs) become increasingly common in analytical systems for rapid characterization of samples, physical insight into location-specific electrochemical performance and functionality of these IDAEs is vital. Such characterization can be performed through the use of scanning electrochemical microscopy (SECM), which is a powerful noninvasive physical methodology for determining electrochemical and topographic characteristics of complex samples. Depth scan SECM imaging was performed for the generation of 2D current maps of an IDAE relative to an ultramicroelectrode (UME) position in the x–z plane. Hundreds of probe approach curves (PACs) and horizontal sweeps were obtained from one depth scan image by simply extracting vertical and horizontal cross-sectional lines. These experimental PACs and sweeps were further characterized through comparison with simulation generated curves through modeling of the experimental system. An UME approach to and horizontal sweep across asymmetric systems such as an IDAE were explored in this paper. Full 3D models of finite element analysis were developed for the above SECM system, providing a deeper understanding of the above PACs and horizontal sweeps by means of SECM feedback in correlation with local concentration profiles. Especially, the transition region of an IDAE, where conductive and insulating substrates meet, was extensively investigated in this work.