A comparison of three electrode configurations for electrical impedance tomography

There are several applications of electrical impedance tomography (EIT) where the electrodes are not placed on the boundary of a circular object. Applications exist in areas such as the measurement of distributed pressure, where a pressure sensitive planar sensor element can have electrodes placed behind it and in process mixing, where the electrodes can be mounted on the centrally placed stirrer(s). For this study, three different electrode configurations have been examined using three measures of performance and by examining the image quality produced by a basic sensitivity algorithm for each electrode configuration. The three electrode configurations examined were the `classical´ circular arrangement, a square arrangement and a distributed arrangement. Various conducting and non-conducting objects or anomalies were placed into the saline solution in each phantom and measures of performance calculated. The anomalies used in the comparisons are varied in both size and conductivity. The three measures used to compare the various electrode arrangements for the same changes in anomaly are the fractional change in boundary voltage (δV/V), the rms change in boundary voltage (Vrms) and the visibility