A Three-layer Tissue-mimicking Phantom for Radiofrequency Skin Treatment

Tissue-mimicking phantoms (TMPs) have been widely used to simulate human tissues in the pre-clinical study. However, the electrothermal properties of the existing radiofrequency (RF) TMPs cannot satisfy the RF heating for skin treatment and may lead to the inaccuracy thermal distribution. In order to improve the accuracy of thermal distribution caused by RF fields in the phantoms, this study has provided a three-layer TMP (TLTMP) including skin, fat and muscle layers based on polyacrylamide gel (PAG). The TLTMP of muscle, fat and skin layers was sequentially fabricated while the electrical conductivity, density, thermal conductivity and specific heat of each layer were measured. The RF-induced temperature elevation was measured in the fabricated TLTMP, and the maximum temperature was fitted by a back extrapolation technique based on a model of the temperature decay. Electrical conductivity is the most important property, and its values of skin, fat and muscle layer measured using the conductivity meter are 0.2204 S/m, 0.0253 S/m and 0.5012 S/m, respectively. The mean experimental maximum temperatures is 60.3 °C with the standard deviation of 0.7 °C. The TLTMP and temperature measurement method can accurately simulate the energy conversion of RF heating for skin treatment. This TLTMP can be applied to accelerate the clinical transformation of RF skin treatment by providing the temperature reference of different phantom sites.