Monitoring of sterilization in an oxygen plasma apparatus, employing a quartz crystal microbalance (QCM) method

With the aim of constructing a system for monitoring sterilization under atomic oxygen, we investigated the applicability of the quartz crystal microbalance (QCM) system, to atomic oxygen generated in a cold oxygen plasma apparatus. We have exposed microorganisms, such as Bacillus subtilis and Aspergillus niger, examined the effects of such exposure, and observed the inactivation properties of these microorganisms. We have confirmed that there is a positive correlation between atomic oxygen exposure and inactivation of microorganisms, quantified by the QCM method using fluorocarbon thin films, and have investigated the relevant inactivation mechanism through scanning electron microscope (SEM) observation and spectrum analysis.

► Extremely low fluxes of atomic oxygen are generated in an oxygen plasma apparatus.
► We succeed in quantifying low fluxes of atomic oxygen using a PTFE-QCM.
► The QCM method is serviceable in assessing inactivation effects on microorganisms.
► The inactivation properties of Bacillus subtilis and Aspergillus niger in response to atomic oxygen are observed.