Evaluation of Excitation Strategy for a Large-Scale ECT Sensor with Internal-External Electrodes

The fringe effect of a large-scale electrical capacitance tomography (ECT) sensor is more serious than a small-scale ECT sensor. As a result, the sensitivity in the central region of a large-scale ECT sensor becomes so low that it is difficult to achieve desired image quality in the central region. To improve the image quality with a large-scale ECT sensor, a combination of internal and external electrodes (IEE) is used, and five two-electrode excitation strategies are presented in comparison with the traditional one-electrode excitation strategy. The images reconstructed by a linear backprojection (LBP) algorithm with the six excitation strategies are analyzed and a modified method is proposed to reduce the effect of noise. The performance of the IEE sensors with the modified LBP and the six excitation strategies is evaluated in terms of the relative error of solids concentration.