Using plasma to combat viruses and bacteria
If a gas is supplied with sufficient energy, a plasma can be generated. The plasma consists of electrons, ionized and excited particles as well as UV light; these lead, amongst other things, to chemical and biological reactions which are very suitable for cleaning and disinfection purposes. The Fraunhofer IST focused its attention primarily on the selection and integration of a suitable plasma source. Due to the application and integrability, following extensive preliminary investigations a piezo-jet system was further developed in which the surface material is treated in a gentle manner by means of a “cold plasma”.
Initially problematic was the formation of ozone, which occurs when the plasma is ignited. “In order to prevent the ozone from escaping into the environment, we identified the optimum extraction conditions by means of simulations and then designed a corresponding concept,” explained Prof. Dr. Michael Thomas, Head of Department at the Fraunhofer IST. “The utilization of absorbents furthermore ensures the complete reduction of ozone from the extraction, as a result of which the plasma source can be used without hesitation for cleaning and disinfection in daily operation.” The final step in the work at the Fraunhofer IST was the implementation of the obtained results in an appropriate design and the construction of a complete plasma system which can be integrated directly into the cleaning robot.
Prof. Thomas is very pleased with the successful development. “It is wonderful that we can provide a small contribution towards making the cleaning and disinfection of surfaces safer and more efficient - particularly in the current situation,” he explained. “The result of our research is a completely self-sufficient plasma system with an integrated generator as well as an extraction system with an ozone-filter unit which, thanks to its modular design, can be easily incorporated into various cleaning robots.” The cleaning and disinfection of surfaces, particularly in indoor areas, constitutes an important field of research at the Fraunhofer IST. Markets here include the interiors of vehicles and means of transport as well as rooms in sensitive infrastructures such as hospitals or care facilities.