Plasma steriliser for medical and aerospace applications

 Photo: Woman holding forceps in a flame

Plasma – the state of matter with the highest energy level – is familiar to many in nature in the form of fire. Using cold plasmas, many items can be efficiently sterilised; ©RUBIN/ Gorczany

Traditional sterilisation methods are no longer effective against all pathogens. By means of plasma, on the other hand, exceptionally stubborn bacteria stems can be killed off, as demonstrated by Junior Professor Dr Katharina Stapelmann from the Institute for Electrical Engineering and Plasma Technology. She has developed a steriliser that is specifically suited for ridding medical instruments of germs efficiently, yet without damaging the material.

Stapelmann designed the sterilisation chamber as a drawer with a surface in DIN-A4 format to hold standard tablets for medical instruments. The drawer may also be used as a sterile container. “You can, for example, put a set that’s going to be used in an appendectomy into the device, sterilise it and store the closed container in the cupboard right until surgery,” explains the researcher. Compared with traditional processes, plasma sterilisation is more energy saving, faster and does not require any harmful radiation or carcinogenic chemicals. Unlike autoclaves, which apply moist heat, the process can be deployed for synthetic components, and it does not damage metal items which an autoclave blunts within a short space of time. A prototype of the steriliser is already available. What is now missing is an industrial partner who will make the product market-ready.

In order to prevent germs from the Earth from getting into space, and germs from space from getting to Earth, it is standard practice to sterilise all aerospace materials. However, not all pathogens are destroyed by this multi-stage process. In collaboration with the German Aerospace Center, Katharina Stapelmann tested her method for metal screws which were riddled with the spores of the particularly stubborn bacterium Bacillus pumilis SAFR032. This bacteria stem has demonstrated the to-date highest resistance against traditional sterilisation methods, such as autoclaves, chemical treatment or UV radiation. The plasma treatment, however, destroyed all germs within the space of only five minutes at a temperature of 60 degrees centigrade.; Source: Ruhr-Universität Bochum