Sensitivity distributions of capacitance tomography sensors with parallel field excitation

Abstract

In conventional electrical capacitance tomography (ECT) systems the single-electrode excitation scheme is used in which an excitation signal is applied to each of the sensor electrodes in turn. This conventional ECT sensor is more sensitive in the wall area than the central area and consequently the signal-to-noise ratio (SNR) in the central area is poor. To improve this situation, a scheme called parallel field excitation has recently been proposed. This paper analyses the sensitivity distributions of the parallel field sensors. Analytical, simulation and experimental results show that the sensitivity maps of the parallel field sensors are simply the linear superimpositions of those of the conventional sensor, and give inferior image reconstructions.