A 36-­electrode electrical capacitance tomography system using asymmetric electrode strategy

Peng Xue, Lihui Peng

National Laboratory for Information Science and Technology Department of Automation, Tsinghua University, Beijing, 100084, China

ABSTRACT

Electrical capacitance tomography has been being studied more than 20 years. Thus far, most of reported ECT system is composed of 8, 12, or 16 electrodes. We presented an ECT system with 36­electrode in this paper. With the increase of electrode number, the capacitance between different electrode combinations becomes smaller, which makes capacitance measurement more challenging. To overcome this, an asymmetric electrode configuration measurement strategy is proposed so that the minimum capacitance to be measured from this ECT sensor does not become smaller significantly than that from the traditional ECT sensor with symmetric electrode arrangement, which makes the hardware easy to be implemented. A 3­SPDT­switch strategy is developed which takes 3 SPDT switches and 2 control wire for each electrode to switch between the excitation terminal, detection terminal or GND of the AC­based capacitance transducer. Reconstructions using the measurement data from this 36­electrode ECT system are also presented.

Keywords Electrical Capacitance Tomography, Multi­electrode ECT, Asymmetric ECT, Image Reconstruction