Study of Oxygen Plasma for Application in Sterilization Processes

The main objective of this work was to propose a technique of sterilization for medical devices with less exposition time than current plasma techniques, and also determine if this technique can be applied to temperature sensitive materials. Therefore, it was used as biological sensor Bacillus subtilis spores var. niger ATCC 9372 and Bacillus stearothermophilus. For Bacillus subtilis indicators were used two substrates: glass with 2,0 x 107 CFU/substrate of microbial load initial, and paper strips with 3,8 x 10 CFU/ substrate of microbial load initial. The efficacy of process was evaluated with the count of survivors and it respective value of decimal reduction (D value). In this work it was used RIE (Reactive Ion Etching). For all processes were used Petri dishes with the sample in triplicates for both microorganisms types. The process parameters was varied as follow: gas flow 100, 200 and 500 sccm, pressure – 100 and 330 mTorr, RF power – 50, 100 and 150 Watts and the time were of 2 minutes up to 60 minutes. After these processes, we made the count of survivors, in order to evaluate the plasma efficiency as sterilizer agent. Espectrophotometric analysis was made to evaluate the oxygen consumption during all process, and was used a scanning electronic microscope to visualize the plasma effect over microorganisms. With these results it was possible to adapt the process parameters for each type of substrate.