Displacement-current phase tomography and electrical capacitance tomography for air-water flow systems

Electrical Capacitance Tomography (ECT) is an imaging modality for spatial reconstruction of the dielectric permittivity distribution inside a region of interest (RoI). ECT utilizes mutual capacitance measurements obtained from electrode sensor pairs placed on a dielectric vessel surrounding the RoI. Displacement-Current Phase Tomography (DCPT) is a variant technique based on the phase information of capacitance measurements enabled by the same harware as ECT. DCPT is predicated on having the sensor plates excited by time-harmonic signals in the quasi-static regime, as commonly done in ECT. Under the presence of lossy media in the RoI, it can be shown that DCPT has an extended linear range (versus ECT) for the dependency between the measurement data and the spatial distribution. This result, together with the fact that no electrical contact is necessary unlike electrical impedance tomography (EIT), makes DCPT, either separately or in combination with ECT, a suitable modality for the reconstruction of lossy media distributions. In this summary paper, we present a comparison between DCPT and ECT results for the imaging of air-water flow systems.