Although the atmospheric pressure plasma jet has wide applications, in this paper, we studied the sterilizing characteristics as one of its applications. Since the highest
temperature for living Escherichia coli is 47.5 -C, we tested the sterilization effect to E. coli using plasma jet of PJ-2 at 1.5 cm away from the nozzle, so as to keep gas temperature at 38 -C.
Fig.6 shows the experimental setup of the sterilizing application. We placed the culture media into which E. coli was implanted beforehand, at 1.5 cm from the nozzle of PJ-2. After the plasma processing, the culture mediums were then kept at 37 -C for 14 h for the incubation. By contrast with untreated culture medium growing E. coli, we plotted the relative area ratio S of colonies versus plasma treatment times in Fig. 7. It is obviously found from Fig. 7 that such a plasma jet source as PJ-2 is very effective in the disruption of E. coli.