Material conformity and bactericidal properties of high-frequency-pulse-modulated and low-frequency-pulse-excited plasmas

H Okawa,T Akitsu

doi:10.1088/1757-899x/369/1/012026

Abstract

Plasma sterilization attracts an increasing attention as an alternative method for chemical sterilization. In this study, we investigate plasma sterilization for practical applications, particularly in dentistry and oral surgery [1]. Helium-diluted oxygen was excited by a dielectric barrier electrode at normal atmospheric pressure. Control of the neutral gas temperature was performed under the plasma sterilization. The relation between the intensity of the spectral emission from the excited oxygen atoms and bactericidal effect was investigated using Bacillus stearothermophilus and opportunistic infection bacterium. A comparison is performed with a low-frequency wide-gap discharge. Degradation and material conformity were investigated using the Tyvek unwoven fabric for the sterile package and soft-silicone resin, methyl-methacrylate powder filler used in the dental surgery.

Highlights

Plasma sterilization attracts an increasing attention for the prevention of infections in hospitals
The neutral gas temperature was fixed at 90°C, and the biological indicator was exposed through a sterile package
A plasma sterilization was realized at the normal atmospheric pressure

Summary

Introduction

Plasma sterilization attracts an increasing attention for the prevention of infections in hospitals. The application of a high-temperature pressurized steam is limited to heat-resistive materials Liquid agents, such as 2–20% glutaraldehyde, provide a disinfection of pathogenic bacteria and coagulation of proteins. We present a comparative study of sterilization using helium mixed with oxygen or nitrogen controlled separately, and material conformity to the sterile package, soft silicone forming material, poly-siloxane, and granular bone cement, methyl-methacrylate. In this experiment, we developed a low-cost power sources to be used in a simple structure of dielectric barrier electrodes, reported for the first time in 1987 by Kanazawa et al [3]. A few studies reported the material conformity and sterilization effect under a controlled power reduction of radical diffusion by the medical equipment in the sterilization process [12]

Experimental methods

Low-frequency discharge

Conclusion