Measurements of the complex permittivity of sodium chloride and tissue mimicking solutions from 100 MHz to 3 GHz

Abstract

The aim of this work was to investigate the dielectric properties of solutions which can be used to mimic the electrical properties of human breast tissues. By analyzing the dielectric properties of tissue mimicking solutions, it is possible to characterise the interaction of electromagnetic fields with the human body, the amount of energy that the body absorbs and how much ionic currents are induced in the body. Previous studies have used sodium chloride (NaCl) and Triton X-100 TM to approximate the dispersive dielectric properties of a variety of human soft tissues from 500 MHz up to 6 GHz. In this study, measurements were conducted on 213, 283 and 403 Triton X-100 in order to mimic different percentages of adipose in breast tissues while extending current knowledge from 500 MHz down to 100 MHz. Measurements were performed at 25 and 37°C. Prior to conducting these measurements, a new, state-of-the-art probe (DAK) was validated by conducting measurements on 0.1 N NaCL The results were analysed and compared to those published in the literature and then fitted to relaxation models. Most dielectric parameters were observed as a function of frequency and temperature. Measurement uncertainty analysis was also performed for both saline and Triton X-100 solutions. These results contribute to further computational research in microwave diagnostic and therapeutic applications in medical physics for safer and more reliable detection of breast cancer as well as application in microwave hyperthermia.