Modeling of Dielectric Properties of Ex Vivo Human Normal Active Liver Tissue in the Frequency Range of 10 Hz to 100 MHz

Accurate knowledge of the modeling of dielectric properties of biological tissues is essential for bioelectromagnetic research. Due to technical limitations and medical ethics, the dielectric properties of human tissues are still mainly measured ex vivo. The dielectric properties of ex vivo tissue are also affected by external environment such as time spent ex vivo, temperature and humidity. The most widely used Cole-Cole model has some limitations in modeling dielectric properties of ex vivo tissues. A simple dielectric property model which is independent of optimization algorithm and initial value, easy to add parameters and more applicable for ex vivo tissues is still needed. This work presented new modeling of the dielectric properties of ex vivo human normal active liver tissue in low frequency range. The mathematical relationship between the conductivity and frequency, the permittivity and frequency could be fitted by a cubic polynomial function and a quadratic Gaussian function respectively. Accuracy evaluation, precision evaluation and statistical analyses confirmed the adequacy of the two models. The comparison between our mathematical models and the Cole-Cole model showed that the mathematical models had better goodness of fit. The significance of this study is to model the dielectric properties of ex vivo human active tissue which still maintain the biological activity, avoiding the great deviation caused by animal tissues or ex vivo inactive tissue in low frequency range. More useful, the knowledge of the new mathematical models of the dielectric properties in this study, are the bases for modeling with external environmental factors in the future as well as for the calculation of dielectric properties of ex vivo tissue at any frequency, any ex vivo time, any temperature and any humidity.