Study On Measurement Of Biological Tissue Dielectric Properties In High Frequency Using Reflection Method On The Open-ended Coaxial

Biological tissue dielectric properties are the characterization of tissue absorbing and coupling the electromagnetic energy in the electromagnetic field and the base of response of biological tissue for the electromagnetic, which are of great significance regardless to the biological theoretical studies or medical applications. Recent years, the measurement of biological tissue dielectric properties has been one of the important research topics in Bioelectromagnetics and Microwave Biochemistry. Although the research and exploration about the measurement of biological tissue dielectric properties have gone through many years, there are still many problems, such as the simpleness of study target, the limit of measurement frequency, the lack of uniform reference standard for the measurement result and so on.With the simulation and actual measurement, this thesis analyzes and studies primary the reflection method on the open-ended coaxial for measurement of biological tissue dielectric properties based on equivalent circuit model in frequency range from 1MHz to 120MHz. The thesis consists of three sections:First, by means of simulation, the measurement of the dielectric properties of several selected materials is achieved using the open-ended coaxial reflection method. Then, the simulation research and exploration about the factors which would affect the measurement results, such as the coaxial probe cross-sectional size, the selection of standard reference materials and the size of analyte is designed for the current disadvantage of the study about this. And the results show that the real part of complex dielectric constant of the standard reference material has a greater impact on the conductivity of the materials under test, while the conductivity of the standard reference material also has a greater impact on the real part of complex dielectric constant of the materials under test, which means the measurement will get the better results, when the corresponding dielectric constant of the standard reference material is similar to the materials under test. As well as, when the probe cross-section and the size of analytes are selected in a small size range, the measurement also will get better results, which provides a strong technical guidance for the actual measurement of the biological tissue dielectric properties.Secondly, according to the actual measurement needs, a simple and reliable calibration method is put forward to make up the difficulties and shortcomings of traditional calibration method which achieves good measurement results in frequency range from 1MHz to 120MHz in the simulation comparing. And the dielectric properties physical model of solutions is built for actual measurement. Meanwhile, the conductivity calculation revised fitting formula is put forward based on measurement results, by which the conductivity measurement errors have been improved. Finally, the dielectric properties measurement test of some parts of the rabbit tissue is designed, and the data attained is compared with the result obtained by the impedance measurement, which shows a more satisfactory measurements.