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article imageNovel plasma flashlight developed to fight wound infections

By Tim Sandle     Apr 7, 2012 in Science
A novel device has been developed which uses cold plasma (an 'electrical gas') to destroy the thick layers of bacteria around wounds. If the prototype is successful it would be used by emergency services and in military operations.
A group of Chinese and Australian scientists, working through the Institute of Physics, have developed a hand-held, battery-powered plasma-producing device that can eliminate a high population of bacteria located on human skin.
The device is described as a "plasma flashlight" in a press release and has been presented in a paper published in the Journal of Physics. To test the device, the science team used the plasma flashlight to kill a thick layer of the bacteria, Enterococcus faecalis. This bacterium which often infects the root canals during dental treatments, and is known to be sometimes capable of developing antibiotic resistance.
For the challenge, a thick layer (for 'microbiological' terms) of bacteria was produced, around 25 micrometres thick . The layer was made up of around 17 different layers of bacteria, and is referred to as a biofilm. Biofilms present a risk at the sight of wounds., for they can form nearly impenetrable barriers, preventing treatments like antibiotics from seeping down any deeper that the first few layers of the structure.
To power the plasma flashlight all that is required is a simple 12 volt battery and it works at room temperature. Plasma is the fourth state of matter (in addition to solids, liquids and gases). It can be described as an ionized gas and it is electrically charged. Plasma reacts with the air, which generates free radicals which kill bacteria cells. However, the exact mechanism of how plasma kills bacteria are unknown.
David Graves, a professor of chemical and biomolecular engineering at UC Berkeley, is quoted by Popular Mechanics as saying "The basic idea is very, very simple. If you pass electricity through a gas by applying a high voltage, you get a plasma."
The Daily Mail reports that the device was designed so that it could be used by medical staff when making emergency calls, or when dealing with natural disasters, or when engaged in military combat operations.
The reference for the paper is:
X Pei, et al. Inactivation of a 25.5 ┬Ám Enterococcus faecalisbiofilm by a room-temperature, battery-operated, handheld air plasma jet. Journal of Physics D: Applied Physics, 2012; 45 (16)
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