Biomedical applications of atmospheric microplasma

Atmospheric microplasma has been intensively studied for use in various applied fields because it can be generated by dielectric-barrier discharge with a discharge gap of only 10–100 μm and a voltage of only approximately 1 kV under atmospheric pressure. A new possible bio-application of plasma, known as “plasma medicine”, is emerging from the work of many researchers throughout the world. One bio-application or medicinal application of atmospheric microplasma is sterilization. The sterilization of Escherichia coli was confirmed after microplasma treatments using Argon and air as the process gases due to the action of active species generated by microplasma. Emission spectroscopy measurements demonstrated the existence of active species A decrease in the bacteria count of more than six orders of magnitude was observed after sterilization with an air-and-vaporized-ethanol microplasma treatment. Observation with a scanning electron microscope (SEM) indicated that the E. coli had a shrunken shape after the microplasma treatment.Another application of atmospheric microplasma is the “surface treatment” of materials that are used in the medical field with long-lived active species generated by microplasma. The materials considered in this study were glass and polymer films. The contact angle of a water droplet on the surface of the polymer films was measured to estimate the films' hydrophilicity. The relation between the contact angle and the treatment time was investigated. The contact angle decreased from 75.6° to 45.6° after 10 s of treatment.