A Miniature Two-Plate Electrical Capacitance Tomography Sensor

As one of tomographic imaging techniques, electrical capacitance tomography (ECT) has been successfully applied to many industrial applications. While ECT sensors are normally circular, some other shapes, such as square and parallel, are demanded for some specific applications. This paper introduces an ECT sensor with a two-plate structure, providing incomplete measurement data only. It is flexible to place the two electrode plates, for fitting a sensing space. Four aspects of the sensor are discussed based on the software simulation: 1) the effective sensing area; 2) the distance between the two plates; 3) the angle between the two plates; and 4) the number of electrodes. A two-plate ECT sensor with 2 × 3 electrodes on each plate is fabricated. Capacitance is measured by an ECT system based on impedance analyzer. Images of different permittivity distributions are generated by linear-back projection and Landweber iteration algorithms. The experimental results show that the two-plate ECT sensor can produce good images similar to a conventional ECT sensor.