New materials for dielectric simulation of tissues

Two novel materials have been developed to simulate the dielectric properties of human muscle and fat at 1000 MHz. These materials, which are based on ethanediol set with gelatine, are easily made and have good mechanical properties. The complex permittivity, epsilon *, of each material was measured with an open-ended coaxial sensor in conjunction with an automatic network analyser. Values of epsilon * at 1000 MHz and room temperature (49.4-24.4j for the muscle-equivalent material, 8.2-3.6j for the fat-equivalent) compared well with literature values for tissue at body temperature. Thermal properties were also considered. Specific heat capacities of the materials at room temperature were measured by differential scanning calorimetry and found to be very close to values predicted by theory. Densities were also measured and the thermal conductivities estimated. For comparison, new measurements were made of the specific heat and density of human muscle and fat at body temperature.