Preliminary study on the inter- and intra-species variability for the dielectric permittivity of animal kidney

In recent years, the interest toward the biomedical applications of electromagnetics is growing, making the accurate and reliable knowledge of the dielectric properties of biological tissues a very active field of research. Several experimental campaigns both on in-vivo and ex-vivo tissues were proposed worldwide, characterising the dielectric properties of biological tissues from about few hundred MHz up to 50 GHz; however, the reported data from different studies do not always converge even when they refer to the same type of tissue or organ. The reasons for this uncertainty could be several; in particular, special attention has to be done to follow a strict measurement protocol, allowing for minimal sample preparation and thus minimal dehydration of sample. This is because at the frequency of interest the polarisation is mainly attributed to the `water' content in the sample under test. Thus, in this paper we propose the use hydration as a possible classifier for accurately processing the measured dielectric properties of kidney samples.