Plasma filter provides an air of cleanliness

Hospitals, factories and homes could have cleaner air thanks to a new plasma-based air filter system developed at the University of Manchester.

Hospitals, factories and homes could have cleaner air with a plasma-based air filter system.

Researchers at the University of Manchester’s chemistry department claim the filter can destroy most bacteria such as those that cause Legionnaire’s disease, plus hard-to-kill spores. It can also wipe out smoke and other particles. Successful experiments have been conducted on eradicating harmful benzene fumes.

The device was originally designed to produce ozone from air for use in sterilisation procedures. The researchers realised, however, that it was even better at cleaning air directly. It was then passed to spin-off company Manchester Innovation and is awaiting a patent.

Unlike with other plasma devices, the air is blown by a fan through the plasma field. Thousands of glass beads in the field are used to break up the airflow to allow more effective cleaning. The device – which is hoped to be commercialised within 15-18 months – works at ambient temperature and atmospheric pressure which means there is no need for a pressurised gas supply or pumps.

Streams of electrons that flow between two porous electrodes bombard and tear apart the molecular structure of any microbes and pollutants that enter the field.The filter still produces negligible quantities of ozone, but can be adjusted to produce more if required for other uses such as sterilisation of a contained and uninhabited environment, said Manchester Innovation’s development manager Dr David Glover. However, it does not produce unwanted nitrous oxide.

He said the filter could be used in kitchens and refrigerators, medical facilities and clean rooms for the production of sensitive electronics. It is envisaged as a ‘final polisher’ to complement other kinds of filter such as ultraviolet or electrostatic treatments, said Glover. ‘These are only about 90 per cent efficient. By adding our system they could become 99 per cent efficient.’

Whereas the efficiency of electrostatic systems decreases over time due to the build-up of dirt the plasma filter, because it eradicates particles as well as microbes, should operate as normal for a couple of years, said Glover.