Capacitance tomography sensor without CMOS switches

Abstract

Usually, CMOS switches are used to select excitation and detection electrodes in electrical capacitance tomography (ECT) systems. However, these switches cause charge injection or coupling leakage problems. An ECT sensor is described which does not use any switches directly connected to the measurement electrodes. The potentials on the electrodes are digitally controlled and the excitation field of the sensor is totally flexible. Experimental results show that the circuit performs well as either an excitation or a detection channel.