能量分布均匀性对恒功率下多极射频诱导胶原蛋白分泌的影响

Radiofrequency (RF) treatments, where heat selectively acts on skin tissue, are widely used to treat and improve wrinkles, capillary dilation, hyperpigmentation and other skin problems.The penetration depth and distribution uniformity of RF energy can beregulated by adjusting the electrode frequency, phase and polarity of multipolar RF parameters, which can significantly improve the energy efficiency compared withmonopolar RF and bipolar RF. In recent years, parameters such as electrode diameter, frequency or phase of multipolar RF have been extensively studied, but the effect of different electrode polarity arrangements on the therapeutic effect has rarely been reported. The aim of this paper is to investigate the effect of the electrode polarity arrangement modes of multipolar RF on the uniformity of energy distribution and its biological effect on skin application. Firstly, a three-dimensional simulation model isestablished using COMSOL Multiphysics software to investigate the effect of three electrode polarity arrangement modes of multipolar RF on energy distribution and heat distribution in skin tissue at constant power. In mode 1, the polarity of each row of electrodes is the same and the polarity of two adjacent rows is opposite. In mode 2, the positive and negative electrodes are staggered. In mode 3, each row/column has two electrodes of the same polarity, while the top and bottom electrodes have opposite polarities.The simulation model couples several physical field modules,including electric field, solid heat transfer and electromagnetic heat, where the electrical and thermal parameters of the skin tissue are referred to a database of fundamental physics experiments. Secondly, in vitro cultured human-derived skin fibroblast HFF-1 cells are treated in three treatment modes of multipolar RF. Cell proliferation, cell activity, and collagen secretion are quantified in the cell biology experiments. Finally, rat dorsal skin is treated to study the effect of different electrode polarity arrangement modes on collagen secretion and skin pathological safety in animal experiments. The simulation results show that in the case of mode 2, the average values of current density and the uniformity of energy distribution of multipolar RF are better than the other two modes. These results also apply to the mean values of temperature and uniformity of temperature distribution for multipolar RF applied to skin tissue. For the in vitro cell experiments, the number and cell viability of fibroblast HFF-1 cells are effectively increased in all treatment modes of multipolar RF. More importantly, however, the total collagen secretion induced by fibroblast HFF-1 cells is increased by about 10% in mode 2 only, suggesting that RF energy distribution and thermal distribution uniformity may be important parameters for inducing collagen secretion by cells. In animal experiments, the average thickness of the collagen layer of rat skin increase by approximately 0.02, 0.13 and 0.06 mm for the three electrode polarity arrangement modes, respectively. In addition, the pathological safety of rat skin is not affected in any of them. The following conclusions can be drawn from the simulation and experimental results: (1)The mean current density, energy distribution uniformity and heat distribution uniformity of multipolar RF acting on skin tissue are relatively optimal at the staggered arrangement of positive and negative electrodes. (2) Multipolar RF treatment can effectively promote the proliferation of skin fibroblasts HFF-1 cells cultured in vitro and enhance cell viability, and the application effect is positively correlated with the uniformity of RF energy distribution. (3) The amount of collagen secreted by fibroblasts and the thickness of rat skin collagen layer increase significantly with the increasing uniformity of RF energy distribution. The treatment process of multipolar RF does not affect the pathological safety of the rat skin.