Evaluation of Effect of Number of Electrodes in ECT Sensors on Image Quality

It is commonly assumed that the use of more electrodes in an electrical capacitance tomography (ECT) sensor would result in higher resolution images. In this paper, the issues with the number of electrodes will be discussed. To investigate the effect of the number of electrodes on the quality of reconstructed images, ECT sensors with different number of electrodes-4, 8, 12, 16, 20, 24, and 32-are investigated. The capacitance between different electrode pairs is calculated for some typical permittivity distributions using a finite element method. The obtained capacitance data are then used to reconstruct images using the projected Landweber iteration algorithm based on both linear and semi-linear ECT models. The sensitivity distributions for the ECT sensors with different number of electrodes are analyzed. The main conclusion is that limited new information can be obtained and little improvement in the quality of images be achieved if the number of electrodes is more than 12.