Compensation for fringe effect of electrical resistance tomography sensor by multiple-plane sensor scheme

Fringe effect exists in conventional ERT sensors, i.e., severe distortions of electric field on both ends of sensor electrodes. This leads to a 3D sensing region for a 2D ERT sensor. As a result, the objects outside the ERT sensor plane can still be sensed and imaged, which is undesired and deteriorates the image accuracy. To tackle with this issue, a three-plane ERT sensor scheme is proposed. Simulation results show that the three-plane sensor scheme can compensate for the fringe effect induced by the object outside the measurement sensor plane regarding a distribution with three non-conductive bars at different cross-sectional and axial positions. Meanwhile, it is found that for axially uniform distributions, the proposed compensation method can reduce the size overestimation of non-conductive objects to be imaged by linear reconstruction method such as the Landweber iteration. Finally, an experimental ERT system is established to verify the findings from simulation.