If the thought of having an anthrax detector small enough to fit in your home smoke detector is exciting, you might want to know what Kansas State University researchers are working on to try to make that possible.
Led by professors Hongxing Jiang and Jingyu Lin, a K-State research team is part of a new consortium founded by the Defense Advanced Research Projects Agency. One of several universities to be a part of this consortium, K-State has been awarded $1.4 million over four years to develop semiconductor ultraviolet light sources, including LEDs and laser diodes for detection of bioagents such as anthrax. Several universities, including Brown University, Cornell University, the University of California at Santa Barbara, the University of Texas at Austin, and several companies are also members.
It takes ultraviolet light to "excite" a bioagent such as anthrax, causing it to give off a light of its own. If you can excite a biological system by ultraviolet light, then the biological agent will emit another type of photon of different wavelength with specific characteristics, making it possible to detect, according to Jiang and Lin.
"We are making better materials and finding the optimal structure to make this ultraviolet source. The other team members are trying to find out how to identify the fluorescence of threatening biological systems," Lin said. "We hope to work together to potentially identify biological threats by using ultraviolet light."
"We know, for example, that anthrax, other bioagents and a lot of materials fluoresce when you shine a small enough light on them," Jiang said. "You need a light with a shorter wavelength to excite these smaller particles."
According to Jiang and Lin, while there are larger ultraviolet lights that can detect these agents, there are currently no miniature ultraviolet LEDs that can enable smaller items -- such as portable devices -- to detect bioagents. The key here, according to the researchers, is making chip-scale and remote detecting devices.
"There's no point to bring a gigantic laser to do tests on a battlefield, for example, so what they want to do eventually is to make chip-scale detection devices for these biological threats," Lin said.
But more than just potential anthrax detectors, ultraviolet lights' short wave length can be very useful for medical purposes as well, since many biological cells and DNAs can be excited by UV light, according to Jiang and Lin.
"UV LEDs are important -- not just for detecting anthrax, but also for the medical field and medical research. In the future, invasive methods can be replaced with light detection. A person with diabetes, for example, would not have to draw blood every day," Jiang said.
Assisting the researchers with their current and new projects are grants from the Department of Defense and the Department of Energy to purchase a $1.2 million commercial Metal Organic Chemical Vapor Deposition reactor.
"We feel very lucky. It's not easy to get this kind of equipment at a university," Jiang said. "As far as we know, it's the second largest machine in the university setting. This machine will open a lot of opportunities for us in the future."
The research team began installing the new machine in January 2002 and have been using the machine since the end of May. The new machine can simultaneously produce six pieces of 2-inch III-nitride wafers.
"It takes us three to four hours
typically to make one-half of a 2-inch wafer on the old machine,"
Jiang said. "With the new machine, we can make six to seven
wafers in the same amount of time. And, we get the uniformity
that we didn't get with our home-built machine."
"Our small machine is still very critical to us. It's where we define the best structure of the wafer," Lin said. "Once we determine the structure of the LEDs using the small machine, we'll put that recipe in the big machine to produce and supply to the people who need it -- collaborators, team members in the consortium, etc."
"We will be able to contribute not only for our research, but for the cause as well," Jiang said. "As part of a team with all kinds of experts, we will be able to supply them with different materials and structures."
Jiang and Lin's research is funded by the grants from National Science Foundation, Department of Energy, Army Research Office, Ballistic Missile Defense Organization, the Office of Naval Research and the Defense Advanced Research Project Agency.
The Defense Advanced Research Projects Agency is the central research and development organization for the Department of Defense. It manages and directs selected basic and applied research and development projects for the Department of Defense, and pursues research and technology where risk and payoff are both very high and where success may provide dramatic advances for traditional military roles and missions.
Jiang and Lin's current research team
includes visiting professor Sixuan Jin; postdoctoral research
associates Tom N. Oder and Zhaoyang Fan; research assistant Wei-ping
Zhao; physics graduate students Jing Li, Kyoung Kim, Jagat Shakya,
Ki-Bum Nam, Mim Nakarmi, and Chakra Maharjan.