Numerical study on atmospheric pressure plasma jets impinging on skin surfaces

The skin structure, including surface geometry and layer thicknesses, significantly affects the behavior and therapeutic efficacy of atmospheric pressure plasma jets (APPJs). However, the interaction between APPJs and structurally varied skin remains insufficiently understood. In this study, a two-dimensional axisymmetric fluid model is developed to simulate APPJ-skin interactions. The effects of hair follicle, as well as the thicknesses of the epidermis, dermis, and fat layer, are analyzed, with particular emphasis on the fluxes of reactive species and the electric field distribution within the skin. Results show that hair follicle enhance both surface reactive species fluxes and dermal electric fields. Local electric field near follicle reaches up to 4×107 V/m, approximately four times higher than that without a follicle. Epidermal thickness strongly influences surface fluxes and electric fields, while dermal electric fields depend on both epidermal and dermal thicknesses. Increase of fat thickness has a limited impact on surface fluxes of reactive species, but can decrease the electric field within dermis layer. These findings reveal how skin structure affects the efficacy of APPJ treatment and provide theoretical guidance for optimizing parameters when applying APPJs to different skin areas.