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. A flashlight portable plasma can kill bacteria in minutes. (Credit :. X. Pei et al Journal of Physics D: Applied Physics )
X. Pei et al, Journal of Physics D :. Applied Physics (2012)
Kill harmful bacteria in hospitals is difficult; on the ground, it can be an even bigger problem. Now researchers may have a means for remote disinfection in a "flashlight" laptop that shines a cold plasma beam to kill bacteria in minutes.
Medical scientists have high hopes for plasmas. Produced in electric shocks, have already been demonstrated that these gas of free electrons and ions to destroy pathogens, help heal wounds, and selectively kill cancer cells. Nobody knows exactly how this works, but it seems that plasmas generate reactive oxygen species called in air. These highly reactive molecules which are present in our own immune system, and oxidize cell membranes damaged DNA.
plasma devices are already in clinical trials to see if they are safe to use. But these prototypes are limited: either they need an external power source to generate many kilovolts required electrical discharge, or they need an external gas supply and regulation to maintain the plasma. Such drawbacks, it is difficult to use the devices in the field of emergency calls, the response to natural disasters or military operations.
A group led by Xinpei Lu engineer at the Huazhong University of Science and Technology in China believes it has a device with none of the drawbacks. Powered by a normal 12-volt battery and operating in the open without a gas supply, the prototype, which they call a plasma torch should be portable enough to last. "It generates the plasma is even unplugged from the wall, even using very low power," said group member Kostya Ostrikov from CSIRO science and engineering materials in Lindfield, Australia.
The battery The lamp pocket is much too small to create a plasma itself, so that researchers use a common electronic device known as a booster to intensify the DC voltage to 10 kV. an output of the amplifier is connected to the shell unit or "earth" in the technical-speak while the other goes to a network of 12 thin, stainless steel needles which create an electric discharge pulsing rapidly. the circuit includes several resistors "ballast" that limit the discharge current so that the flashlight is safe to touch.
to test the device, the Lu group grew thick films of Enterococcus faecalis , bacteria which are known to infect root canals in the mouth and are highly resistant to heat and antibiotics. The researchers used some of biofilms supposedly that of the control samples and subjected others to the plasma torch for 5 minutes at a distance of 5 mm. Thereafter, they scored all samples with two fluorescent solutions: green indicates that the living cells, and red indicates that the dead cells.
The team found that the control samples remained green, while the treated samples had turned almost entirely red-even at the bottom of biofilms, which were about 17 deep cells. The results, which are published online today in the Journal of Physics D: Applied Physics , were still better than a nonportable plasma device that Lu had previously tested group.
Making truly portable device is a great advance, said Michael Keidar, a plasma physicist at George Washington University in Washington, DC "cold plasma operation in air is difficult, [and] it seems that they were able to operate, "he said. "This is a purely technical issue that has been resolved."
Miran Mozetic Engineer of the Jožef Stefan Institute in Ljubljana, Slovenia, highlights another advantage of the plasma torch: It uses only a meager 60 milliwatts per discharge. "This is an important fact because it indicates the battery [will] not to be exchanged or refilled frequently," he said.
Like any other medical device, the plasma torch will go through rigorous clinical tests. But Ostrikov said that in addition to smaller and optimizing its efficiency, the plasma flashlight is "almost" a device already shopping.
CORRECTION: This story has been given primary affiliation Kostya Ostrikov as the University of Sydney, while in fact CSIRO Materials Science and Engineering. The article has been corrected.
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