Biological Tissue Electrical Parameters Of The Microwave Measurement Methods And Application

With the development of microwave or RF techniques, the applications of MW or RF energy in cancer coagulation therapy are becoming more and popular. This paper is mainly focused on the theoretical methods and engineering applications of complex permittivity measurement for biological tissues. Based on the resonant cavity perturbation theory and the transmission line theory, the complex permittivity can be extracted from the resonant frequency or reflection coefficients, this technique is thus employed to measure the complex permittivity of biological tissues.The complex permittivity of biological tissue is a crucial parameter for pre-estimating the temperature distribution in the Microwave Coagulation Therapy. Percutaneous Microwave Coagulation Therapy (PMCT) probe is a coaxial radiation probe used in the therapy, which is used for the permittivity measurement of biological tissues in this work. With the use of the coaxial PMCT probe, the implanting measurement of the biological tissues can be achieved. Four approximation models are used to extract the permittivity of the biological tissues from the measured reflection coefficients. The biological tissues with high and/or complex permittivity are measured to verify the validity of the proposed approximation models.Rational Function Model (RFM) is an approximation of the terminal impedance for a coaxial probe using the Taylor series expansion. Through the adjustment of the series parameter, the simulation coefficients of the PMCT probe can be obtained. The RFM corresponding to the PMCT probe is used for the complex permittivity measurement. Furthermore, the uncertainty analysis and the investigation on the calibration are carried out. On the basis of the uncertainty analysis and calibration, the permittivity and conductivity of the porcine extracted liver and fat tissue are measured.