Advances in spectral electrical impedance tomography (sEIT) towards accurate imaging in the mHz to kHz frequency range

Spectral electrical impedance tomography (sEIT) has received an increased interest in recent years given its promising capability to image the subsurface complex electrical conductivity. However, there are a range of challenges that need to be addressed before sEIT will gain widespread acceptance. In this work, we present significant improvements in the sEIT method, including data inversion and electromagnetic (EM) coupling reduction. A novel complex inversion strategy was proposed and compared with existing strategies. It was found that the newly proposed complex inversion strategy can provide reliable inversion results especially in the presence of large phase angles. Data filtering methods were proposed to deal with EM coupling effects that affect the measurement accuracy above 50 Hz. With the use of the proposed data filters, we achieved plausible inversion results without correction for EM coupling effects up to 1 kHz.