Old Dominion University
September 27, 2005
SourceNews of a “plasma pencil” developed by Old Dominion University researcher Mounir Laroussi was flashing through the World Wide Web in late September, adding to his reputation as a pioneer in the field of cold plasmas.
PhysicsWeb noted Laroussi’s creation of a “hand-held device that can produce room-temperature plasmas … to kill bacteria, heal wounds and treat plaque.” The article, published Sept. 20, included a photo and schematic drawing of the device.
News@Nature.com published a longer article on Sept. 23 calling the invention “a miniature light sabre” and quoting from an article Laroussi wrote this summer for Applied Physics Letters describing how the device works.
Laroussi, associate professor in ODU’s Department of Electrical and Computer Engineering and a researcher at the Frank Reidy Research Center for Bioelectrics, was assisted in the development of the plasma jet by Xin Pei Lu, a postdoctoral researcher at the Reidy Center. The center is operated by ODU and the Eastern Virginia Medical School.
Also, as the News@Nature article points out, Wayne Hynes, associate professor in the ODU Department of Biological Sciences, is working on health service applications of the plasma jet.
Plasmas, sometime called the fourth state of matter along with solids, liquids and gases, are generated anywhere atoms are stripped of electrons, creating soups of neutral particles, charged ions and electrons. Plasmas can be found in solar flares and around lightning bolts, and, in fact, make up 99 percent of the known universe because of their common presence in interstellar space. In the denser Earth’s atmosphere, most plasmas are super hot and hard to control.
During the last decade numerous researchers have produced low-temperature plasmas, but Laroussi, since the mid-1990s, has been at the forefront of the research. His focus has been on ease of use and low-cost generation of plasmas. Business Week magazine named him an “expert” in cold plasmas, and gave the same designation to Karl H. Schoenbach, ODU’s eminent scholar of electrical and computer engineering, who is director of the Reidy Center and holds the Batten Endowed Chair of Bioelectric Engineering.
Cold plasmas are generated when an electrical source is tailored to kick lighter electrons into high speeds without doing the same for heavier ions. This can be done with electricity that is turned on and off—or pulsed—thousands of times a second. The relative inactivity of the ions eliminates the high heat that plasmas can develop in the Earth’s atmosphere and gives researchers the more manageable cold plasmas.
The plasma pencil represents Laroussi’s latest achievements in the production of cheap and reliable cold plasma. His easy-to-handle device is about 5 inches long and 1 inch in diameter, and produces a plasma jet or plume that is adjustable from one-half to 2 inches long. Unlike other hand-held plasma jets, this device poses no risk of arcing or heating up during prolonged use.
The plume produces only a slight tingle, and no harm, when it is directed at human skin. Nevertheless, highly reactive oxygen atoms in the plume can attack bacteria. Laroussi envisions the device being used to disinfect small articles or surfaces, to treat wounds, and even to attack plaque-making bacteria in the mouth. He believes that one day such a device could destroy tumors without damaging surrounding tissue. The Reidy Center is developing and experimenting with technologies that would allow the precise elimination of cancer cells.
Mohammad A. Karim, ODU vice president for research, was on the faculty of the University of Tennessee when he met Laroussi, who was a doctoral student at the time. “At ODU he has significantly advanced the state of the art,” Karim said. “His plasma pencil is very small and can work at least eight hours at a time. While surgical blades often damage surrounding tissues, the plasma pencil can be suitably adapted to kill cancer cells, only a few layers at a time.”
The dean of ODU’s Frank Batten College of Engineering and Technology, Oktay Baysal, added: “This invention is yet another testimonial that Dr. Laroussi and his colleagues in the college think boundlessly when it comes to applying such disruptive technologies so innovatively.”
“It’s a very exciting product,” agreed Zohir Handy, who directs the ODU Office of Technology Licensing. He has sent brochures about the plasma pencil to companies that may be interested in its commercial production.
Laroussi has developed larger cold-plasma generators in the last five years, and applications on scales larger than the pencil could revolutionize sterilization processes for hospitals, industry and the military, he said.
He also received a patent last February for a new type of ultraviolet lamp—UV and fluorescent lamps also utilize plasma—that is ultra-efficient and can be used to disinfect articles and purify water. Patents are pending on his cold plasma innovations.
This summer Laroussi was interviewed by the Discovery Channel about potential use of cold plasmas for defensive shields in space. A plasma field enveloping an aircraft, a missile or a satellite could, theoretically, neutralize bursts of microwaves or particle beams fired by an enemy from Earth or an aircraft. The same kind of field may someday “cloak” aircraft by redirecting enemy radar. Laroussi has received about $500,000 from the Air Force in recent years for research in defense-related cold-plasma applications.
Before joining the ODU Applied Research Center in 1998, Laroussi studied at the University of Technical Sciences of Tunisia, the School of Radio-Electricity in Bordeaux, France, and earned a doctorate in electrical engineering from the University of Tennessee. He received the 1996 Advanced Technology Award from the Inventors Clubs of America. He also received the prestigious Second Millennium Graduate of the Last Decade (GOLD) Medal from the Institute of Electrical and Electronics Engineers’ Nuclear and Plasma Sciences Society.