A critical approach to plasma sterilization is presented with the aim of sterilizing biocompatible materials such as TiO2 and polymer implants. Oxygen plasma was applied to sterilize glass and aluminium samples containing Bacillus subtilis spores. Sterilization was performed with a low pressure weakly ionized oxygen plasma created with a RF generator with an output power of 300 W and frequency 27.12 MHz. The density of charged particles, density of neutral oxygen atoms and the electron temperature were about 1 × 1016 m−3, 1.5 × 1022 m−3 and 5 eV, respectively. The sterilization effects were observed by SEM and by bacterial cultivation. It was found that the surface recombination of O-atoms plays an important role, since it causes temperature changes in the substrate. The sterilization efficiency increased with increasing plasma exposure time. The results showed that the sterilization efficiency is not necessarily just the effect of oxygen plasma radical interactions, but also of the sample heating due to radical interaction with the substrate. Plasma sterilization should be done differently according to the substrate material used for sterilization.

An innovative antibacterial thin film with imbedded silver nanoparticles (AgNPs) is investigated through atmospheric pressure plasma deposition. The process is based on a single‐step fabrication of nanocomposite films where AgNPs are fed directly into the discharge zone. The morphology and stoichiometry of the thin films, characterized with SEM/EDX, GD‐OES, and XPS, can be tailored by the plasma parameters and the quantity of introduced AgNPs. An exceptional 32 at% of AgNPs is reached in the work. The antibacterial assays using Escherichia coli and Staphylococcus aureus strains show effective antibacterial activity of the films and indicate that the fabrication of nanocomposite films using atmospheric pressure plasma represents a feasible way to overcome the issue of device related infection.

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Optical emission spectroscopy was applied for plasma characterization during sterilization of substrates contaminated with bacteria. The amount of 1010∕ml cells of Escherichia coli was carefully applied to glass substrates and exposed to oxygen plasma glow discharge at different pressures between 30 and 200Pa. Plasma was created in a glass discharge tube by an inductively coupled rf generator at the frequency of 27.12MHz and output power of about 250W. The electron temperature and plasma density were estimated with a double Langmuir probe. They were between 3 and 5eV and 2 and 35×1015m−3. Density of neutral oxygen atoms was measured with a catalytic probe, and was between 2 and 6×1021m−3. Optical emission spectroscopy was performed with a low resolution spectrometer. The emission from carbon monoxide and nitrogen molecules was used to monitor the evolution of bacteria degradation. Both signals expressed a well defined maximum corresponding to peak erosion of bacteria by plasma radicals. As the sterilization was accomplished, both CO and N2 lines fell below the detection limit of the spectrometer. The bacteria degradation was also monitored by scanning electron microscope (SEM) and culturing. The SEM images corresponded well with the evolution of CO and N2 lines so the optical emission spectroscopy found a reliable tool for monitoring the sterilization process.

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