Detection and imaging of electric conductivity and permittivity at low frequency

This paper is concerned with low frequency electrical impedance imaging, which is the process of constructing images of the electrical impedance of a body's interior based upon measurements of voltage and current made at the body's surface. The electrical impedance accounts for both resistivity and permittivity. This paper shows how permittivity can be exploited to improve the performance of an electrical impedance imaging system. We show that explicit use of the independent information in the data due to the permittivity will ehance a system's ability to distinguish objects in the interior of a body. In addition, we report the results of experiments performed using the Rensselaer ACT 2 system on a saline bath containing various objects. These objects include both living tissue and metal conductors with oxide layers. We demonstrate the system's ability to distinguish these objects, and we exhibit gray scale images of both their resistivity and permittivity distributions.