Mathematical modelling of the influence of ultra-micro electrode geometry on approach curves registered by scanning electrochemical microscopy

Abstract

Scanning electrochemical microscopy (SECM) is an emerging electroanalytical sensing technique, used to investigate the electrochemical properties of the sample by ultra-micro-electrode(UME) scanning probe. UME signal usually is the current, which depends not only on the properties of the evaluated system but also on UME characteristics such as geometry. Variations of UME geometry can decrease accuracy of the measurement, and then correct analysis of the SECM data becomes almost impossible. In the present work, we studied the precision of measurements with three different the most frequent types of defected UME’s ((i) recessed-UME, (ii) out- warded-UME, (iii) cone-UME). Measurement results were compared with that obtained with not defected standard-plane-UME. Computational experiment was performed with SECM model using diffusion equations with non-rectangular border conditions to calculate esti- mated currents for these three types of defected UMEs and to compare them with that for standard-plane-UME. In order to test the correctness of the model, computa- tions for recessed-UME model were compared with data of real-recessed-UME experiment.