A Wideband Contactless Electrical Impedance Tomography System

This work focuses on the development of a wideband contactless electrical impedance tomography (EIT) system. The system is developed from the aspects of the multifrequency capacitively coupled electrical impedance tomography (CCEIT) hardware, the impedance calculation model, and the system evaluation. The hardware includes a 12-electrode CCEIT sensor, six sensing modules, a data acquisition module, and a personal computer (PC). The impedance calculation model is established by combining the mechanism modeling of the integrated circuits (ICs) and the empirical modeling of the measurement data with the least squares (LS) method. Experiments were carried out to evaluate the developed system, including the signal-to-noise ratio (SNR), the impedance measurement accuracy, and the imaging performance. The experimental results show that the system achieves an SNR above 65.00 dB for frequencies up to 20 MHz. Impedance measurement results indicate that the system has good impedance measurement accuracy at frequencies below 10 MHz and acceptable impedance measurement accuracy at 10–20 MHz. It has particularly good performance at several specific frequencies, which can also serve as a high-performance single-frequency contactless EIT device. Imaging results show that the spectroscopic images reconstructed by the developed system are consistent with the actual distributions. Few types of research on contactless multifrequency EIT (MFEIT) systems have been reported. Therefore, this work is of great significance for further development and practical application of the newly emerged contactless EIT technique.