Measuring Method And Experimental Study Of Thermophysical Parameters Of Bio-tissue

The thermophysical parameters of biological tissue, including the thermal conductivity, the thermal diffusivity, the blood perfusion, the metabolic heat rate and the arterial blood temperature, are the basic parameters for bio-heat transfer research. The estimation of the thermophysical parameters of biological tissue is important for the research of biological heat and mass transfer, for the establishment and validation of bio-heat transfer equation, for the understanding of the thermal response of the biological tissue under outer-supplied heating energy, for the related study of physiology and medical engineering. Particularly during the thermal therapy of cancer, the temperature of the therapy region should be exactly controlled in order to make the temperature of the tumor in the therapy temperature and the temperature of the normal tissue in the safe temperature. Therefore, the thermophysical parameters of the tumor and its surrounding normal tissue should be accurately estimated. Thus the heat source can be well controlled to construct a required temperature field, and an effective treatment can be achieved.In this paper, the measuring methods of the thermophysical parameters of biological tissue were studied. The related measuring devices were developed. And some thermophysical parameters of living and dead tissue were measured.The step-temperature technique is a transient thermal technique to measure tissue thermophysical parameters according to the thermal response of tissue. In this paper, a sensitivity analysis of the step-temperature technique was performed. Particularly, the model error of the step-temperature technique was discussed by using numerical experiment method. An optimal measurement time window was found. The choose principles of the bead parameters and the measuring parameters were put forward. A new reasonable interpretation for the previous experiment phenomena was found. On the bases of the sensitivity analysis, a measuring device for the step temperature technique was developed. A supple thermistor probe was designed, in which the thermal insulation and electricity insulation were achieved. The calibration method of the thermistor bead was introduced. The measurement precision was validated by measuring the thermal conductivity of the mixture of glycerol and agar-gelled water. The results showed that the maximum measuring error was 1.7%, and the average measuring error was 1.09%. The measuring device was used to study the effects of water content and thermal coagulation on the thermal conductivity of biological tissue. The formula about the water content and the thermal conductivity of pig liver was found. The thermal conductivity of protein and lipid was derived from the formula. The thermal coagulation is caused by the tissue structural protein thermal denaturation. The major compositions of egg albumen are protein and water. Therefore, egg albumen was used as a medium for studying the effect of thermal coagulation. And then, pig liver was used. The results showed that the thermal conductivity of egg albumen increased slightly after undergo a thermal coagulation process. However, the thermal conductivity of pig liver just decreased a little in spite of the water content of pig liver decreased so much. These phenomena demonstrated that thermal coagulation has a considerable influence on the thermophysical parameters of biological tissue.The pulse decay method developed by Chen et al is also a transient thermal technique for measuring of tissue thermal conductivity. Comparing with the step temperature technique, the pulse decay method needn't to control the probe bead temperature by using a complicate controlling modular, thus is easier to achieve. In this paper, a sensitivity analysis of the pulse decay method was performed. A measuring device for the step temperature technique was developed. In order to meet the requirement of practical measurement, an improved thermal pulse decay method was presented. The thermal conductivity of the mixture of glycerol and agar-gelled...