SENSITIVITY DISTRIBUTIONS OF CAPACITANCE TOMOGRAPHY SENSORS WITH PARALLEL FIELD EXCITATION

In conventional electrical capacitance tomography (ECT) systems the si ngle-electrode excitation scheme is used in which an excitation signal is applied to each of the sensor electrodes in turn. This conventiona l 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 i s poor. To improve this situation, a scheme called parallel field exci tation has recently been proposed. This paper analyses the sensitivity distributions of the parallel field sensors. Analytical, simulation a nd 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.