Killing harmful bacteria in hospitals is difficult; out in the field, it can be an even bigger problem. Now, researchers may have a means for remote disinfection in a portable "flashlight" that shines a ray of cold plasma to kill bacteria in minutes.
Killing harmful bacteria in hospitals is difficult; out in the field, it can be an even bigger problem. Now, researchers may have a means for remote disinfection in a portable "flashlight" that shines a ray of cold plasma to kill bacteria in minutes.
Medical scientists have high hopes for plasmas. Produced in electrical discharges, these gases of free electrons and ions have already been shown to destroy pathogens, help heal wounds, and selectively kill cancer cells. No one is exactly sure how all of this works, but it seems that plasmas generate so-called reactive oxygen species in the air. These highly reactive molecules, which are present in our own immune system, oxidize cell membranes and damage DNA.
Plasma devices are already undergoing clinical testing to see whether they are safe to use. But these prototypes are limited: Either they need an external power source to generate the many kilovolts required for the electrical discharge, or they need an external gas supply and regulation to sustain the plasma. Such drawbacks make it difficult to use the devices in the field for emergency calls, natural disaster responses, or military operations.
A group led by engineer Xinpei Lu at the Huazhong University of Science and Technology in China believes it has a device with none of these drawbacks. Powered by a normal 12-volt battery and operating in open air without a gas supply, the prototype, which they call a plasma flashlight, should be portable enough to take anywhere. "It generates the plasma even being disconnected from wall power, even using very low power," says group member Kostya Ostrikov of CSIRO Materials Science and Engineering in Lindfield, Australia.
The flashlights battery is far too small to create a plasma on its own, so the researchers use a common electronic device known as a DC booster to step up the voltage to 10 kilovolts. One output of the booster is wired to the devices shell—or "grounded," in technical speak—while the other goes to an array of 12 fine, stainless steel needles that create a rapidly pulsing electrical discharge. The circuit has several "ballast" resistors that limit the discharges current so that the flashlight is safe to touch.
According to news.cell