Development of an Electrical Capacitance Tomography system using four rotating electrodes

This paper presents an Electrical Capacitance Tomography (ECT) sensor scheme consisting of N segments linked in four groups, treated as single, extremely broad electrodes forming a 4-electrode sensor. This configuration is repeated along the pipe circumference, selecting different segments in order to form N/4 independent 4-electrode schemes. The response of this sensor is studied by means of Finite Element Method (FEM)-based simulations, and the results are compared to the response of a 12-electrode conventional sensor. The image reconstruction proved to have lower error when using the segmented sensor, and it is less sensitive to white noise affecting the measurements. A tomograph with 20 segments based on a FPGA core has been developed and tested using a test phantom. Results show that high values of inter-electrode capacitances and better image reconstruction can be achieved.