I want to measure the depth of the tissue using dielectric constant/permittivity. In the attached picture different color represents different material. I want to measure the depth of the first layer. I have a probe, which have 3 or more than 3 electrodes attached on it (with known inter-electrode distance). My system can excite any of the probe electrodes (with some specific electric signal) and can receive signals from any of the probe's electrode.
Now having this kind of setup, how can I measure the depth of any material or tissue. Any, proper paper, book or any related work will be appreciated.