Measurement of the thermal diffusivity of tissue at low temperatures

Glendenning, Neil (1983) Measurement of the thermal diffusivity of tissue at low temperatures. University of Southampton, Doctoral Thesis.

Abstract

The measurement of the thermal diffusivity of tissue as an aid to the development of cryosurgical procedures using a cylindrical heat sink of constant strength and previously developedd mathematical solution was found to give erroneous results. A numerical method was developed allowing the determination of the thermal diffusivity of a uniform isotropic medium initially at a uniform temperature when cooled by an axially located cold source of unknown strength, from the measurement of temperature-time responses of thermocouples located at measured positions within the medium. The method used finite difference approximations for the partial derivatives occurring in the Fourier heat conduction equation describing the physical process. The technique was employed to measure the thermal diffusivity of gelatine gels of various concentrations, ice, pig liver, pig kidney, pig fat and glycerol in a limited number of experiments, using liquid nitrogen or anti-freeze and water mixtures as the refrigerant; a micro-computer based data acquisition system having been designed to control the experiment.

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