The practice of sterilising surgical tools and devices has helped radically improve healthcare. Researchers in the Netherlands are trying a new method, using plasma to kill bacteria inside sealed containers.

But the old mainstay is a 130-year-old device called an autoclave, which is something like a pressure steamer.

Its advantage is that the unsterile tools can be packed into sealed containers and then processed, staying sealed and sterile after they are removed.

Norbert Koster and his colleagues at TNO Science and Industry, an independent research organisation in the Netherlands, are developing a new way to sterilise medical devices.

By sealing them inside plastic bags and then using electromagnetic fields to create plasmas - partially ionised gasses that contain free electrons and reactive ions.

Scientists have known that plasmas have the ability to kill bacteria and sterilise objects, but the major problem has always been that plasma-sterilised objects still had to be packed into a sealed container afterwards. There was no way to sterilise them inside sealed containers.

Now Koster and his colleagues found a way to sterilise medical tools by sealing them inside vacuum bags and then placing them in chambers that are at even lower pressure.

This causes the vacuum pack around the tools to puff out. Then they use an electromagnetic field to remotely ignite a plasma inside the bag, killing the bacteria and viruses therein.

When the process is finished and the bag is removed from the chamber, the outside pressure causes it to shrink down again to closely wrap the now sterilised objects, keeping them sealed.

At the moment, Koster and his colleagues are investigating how long the discharge needs to be to destroy all the bacteria and viruses, says a release of the American Institute of Physics.

This technique is not likely to replace the traditional autoclave any time soon, but it opens up the possibility of sterilising new types of instruments, including detectors and other fancy electronics that would otherwise be damaged.

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