| Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2014) | |
| Biomaterial Interfaces | Thursday Sessions |
| Session BI-ThM |
| Session: | Plasma Bio, Medicine & Agriculture |
| Presenter: | Satoshi Hamaguchi, Osaka University |
| Authors: | I. Ikuse, Osaka University S. Hamaguchi, Osaka University |
| Correspondent: | Click to Email |
Numerical simulations of chemical reactions and diffusion of reactive species in water exposed to an atmospheric-pressure plasma (APP) have been performed based on one-dimensional reaction-diffusion equations. When a living tissue is exposed to a low-temperature APP, there is almost always a liquid layer, such as blood, lymph, or other body fluid, that separates the gas phase and the tissue. Therefore charged and chemically reactive species generated by the plasma are transported through the liquid before reacting with the tissue surfaces. The aim of this research is to understand how and where such chemically reactive species that affect biological matters are generated and transported through a liquid. While a variety of ions, excited atoms and molecules as well as chemically reactive charge-neutral species (including free radicals) are generated in the gas phase, the majority of highly reactive species may decay or be converted to more stable species before reaching the liquid surface. On the other hand, charged species and highly reactive charge-neutral species generated in the gas phase near the plasma-liquid interface are likely to be adsorbed by the liquid surface and to generate highly reactive species in a very thin layer (with a thickness 10 ~ 100 nm) of liquid just below the liquid surface. In the simulation, gas phase species generated by APP are assumed to enter pure water at their thermal velocities and dissolved without any barrier. The model incorporates 37 species and 111 chemical reactions in water at room temperature. The simulation has indicated the presence of such a thin liquid layer (which we call a “reaction boundary layer”) at the plasma-liquid interface, only in which highly reactive species such as OH radicals and solvated electrons exist and rapidly generate less reactive species such as H2O2, which are then transported to the bulk liquid by diffusion.