Long term exposure of atmospheric dielectric barrier discharges onto wet tissue

The interaction of plasmas with liquids is increasingly important in biomedical applications, from sterilization to wound healing. The dose, the time over which plasma is applied, is critical to these applications. For bacterial sterilization, a few seconds to a few minutes are necessary.[1] Exposure to high dose of plasma can cause cell death.[1] Tissues treated by plasmas are often covered by a thin layer of a water-like liquid. The liquid serves as a filter, processing radicals prior to their reaching the tissue. In this paper, we report on a computational investigation of the interaction of DBDs with a thin liquid layer covering tissue. These simulations were performed using nonPDPSIM, a 2-dimensional model in which Poisson´s equation, electron temperature equation and transport equations for charged and neutral species are solved. The liquid layer is treated identically to the gas as a partially ionized substance. Liquid evaporates into the gas with a source given by its saturated vapor pressure. The rate of transport of gas phase species into the liquid is determined by Henry´s Law. The liquid layer, typically hundreds of microns thick, is water containing dissolved O_2aq (aq means aqueous species) and alkane-like hydrocarbons (RH_aq).