Imaging floating metals and dielectric objects using electrical capacitance tomography

Electrical capacitance tomography (ECT) is a well-established industrial process tomography technique. The application of ECT is generally limited to imaging insulating objects with permittivity contrast. Although ECT imaging for grounded conductors are studied earlier, there is not a systematic study of imaging floating metals using ECT. To broaden the application of the ECT, imaging of suspended metallic samples is studied in this paper. Placing a metallic conductor between electrodes has an effect of shortening the spacing between the electrodes, thus the capacitances are increased. This increment in capacitances can be regarded as placing a dielectric sample with higher permittivity than the reference data. An ECT image of the floating metallic samples can be reconstructed using traditional sensitivity based image reconstruction, which is in the same way as imaging dielectric permittivity. In this paper, both metallic and dielectric samples are tested, and the results show the feasibility of ECT imaging for floating metals.