An evaluation of the rotation of electrodes in multi-plane electrical capacitance tomography sensors

The structure of electrodes in a multi-plane electrical capacitance tomography (ECT) sensor is vital for obtaining high-quality capacitance measurements and good images. In this paper, issues with the relative position of electrodes on each plane in three-plane ECT sensors are discussed. Five ECT sensors with different structures are compared by numerical simulation. For the five sensors, the electrodes on the second and third planes are arranged with rotation angles of 0° and 0°, 0° and 15°, 0° and 30°, 0° and 45°, and 22.5° and 45°, respectively, relative to the electrodes on the first plane. The capacitance data obtained from different sensors by numerical simulation are used for image reconstruction using linear back projection and Landweber iteration algorithms. The image quality is evaluated quantitatively in terms of image error. The sensitivity distributions of all the ECT sensors are compared. The effect of the rotation angles of electrodes on the stability of measured capacitance and on the image quality is also evaluated by experiment. The main conclusion is that the electrodes with no rotation angle should be chosen.