On the dielectric/thermal characterization and calibration of solutions and materials for biomedical applications

The exact and unambiguous knowledge of the dielectric and thermal properties of biological tissues, as well as tissue-mimicking phantoms, is of fundamental importance for the design of all types of microwave systems for both diagnostic and therapeutic purposes that have been taking place in recent years. Several research groups around the world have been studying the dielectric and thermal properties of biological tissues for several years and numerous databases have been proposed. This paper presents some preliminary results about a cross study on the dielectric and thermal properties of known solutions, in order to tune the measurement systems for the future analysis on more sophisticated tissue-mimicking mixtures. As an example of the possible set of measurements intended for such a study, two different setups are discussed. First, the impact on dielectric measurements of the system calibration temperature $(23^{\circ}\mathrm{C}$ and $80^{\circ}\mathrm{C})$, for a 0.1M NaCl solution, representative of tissues with an high water content, is outlined in the frequency range 0.5–30 GHz. Then, the thermal properties of sunflower oil, representative of tissues with a low water content, are characterized in a temperature range from $35^{\circ}\mathrm{C}$ to $45^{\circ}\mathrm{C}$.