I. Introduction
With the advantages of low cost, high speed, simple structure, and no radiation, electrical impedance tomography (EIT), also called electrical resistance tomography (ERT) in process tomography, has become a widely accepted technique for distribution reconstruction of conductive medium, which is applicable in both industrial processes and biomedical cases [1]–[5]. However, there still exist some issues limiting its practical applications. One problem of traditional EIT is its contact measurement principle. The contact between the electrodes and the measured medium has some unfavorable effects, such as electrochemical erosion, polarization effect, and electrode contamination, which are more prominent in practical industrial applications [2], [6]–[8], and contact impedance, which is notable in biomedical applications [9], [10]. To avoid the problems resulted from contact measurement, Wang et al. [11], [12] proposed the capacitively coupled electrical resistance tomography (CCERT) in 2013, which refers to the contactless measurement idea of capacitively coupled contactless conductivity detection () technique [13], [14]. Although the sensor structure of CCERT is similar to that of electrical capacitance tomography (ECT), which is basically for imaging dielectric or low-conductive materials, CCERT is regarded as a new kind of ERT that focuses on the imaging of conductive materials. The “CC” in CCERT comes from , indicating the keywords of the contactless measurement idea.