CERAMIC-BASED OZONIZER FOR HIGH-SPEED STERILIZATION

A high-speed ozone sterilizing device has been developed, using a ceramic-based ozonizer of the high-frequency surface discharge type. The advantage of this ozonizer is that it can produce a high concentration of ozone with its compact size which allows its use in a limited space. Oxygen is used to produce the standard ozone concentration of 20 000 ppm. Even at this high concentration, complete sterilization for the reference bacteria—Bacillus subtilis—in a limited time (ca. 3–5 min) is only possible in the case when adequate temperature and humidity are maintained in the ozonized oxygen gas (50°C and ca. 80 percent relative humidity). The object to be sterilized is cleaned with a wet paper, to provide such humidity in the sterilizing chamber, which is kept at 50°C. For reference bacteria, this device produces the standard sterilizing effect of killing one million cells in 3–5 min. One run, including processing before and after sterilization, lasts 12–14 min. The conventional method of using an autoclave requires ca. 30 min. The method of using ethylene oxide gas requires an even longer time, ca. 45 min, and more complicated processing. The present high-speed sterilizer using a high concentration of ozone has been applied in the sterilization of a handpiece used in dental work for drilling teeth. © 1990 IEEE