Numerical Study on the Penetration of an Atmospheric Pressure Plasma Jet Into a Hair Follicle

A 2D axial‐symmetric plasma‐fluid model was constructed to reveal the penetration of plasma into a hair follicle embedded in skin that irradiated to an atmospheric pressure plasma jet (APPJ). Experiments on APPJ interacting with a homemade skin model were conducted to validate the model. With positive polarity, a lagged and slow penetration into the hair follicle occurred due to the electric potential barrier at the entrance of the follicle. For negative APPJ, no electric potential barrier existed, and penetration occurred almost simultaneously with the jet reaching the surface. Reactive species presented were more uniformly distributed along the follicle surface in the negative case. Furthermore, a parametric study quantified the influence of hair diameter and length on these phenomena.