Distributed June 19, 2002
News Service Contact: Scott Turner
Team to build compact warning system for anthrax, other bioagents
A Brown-led team of investigators has received $8.4 million from the Defense Advanced Research Projects Agency to build a small laser-based bioagent warning system for use in buildings or homes or for troops to carry in their backpacks in the field.
PROVIDENCE, R.I. — A Brown University-led research team has received $8.4 million to create a compact warning system for airborne biological agents including anthrax. The award comes from the Defense Advanced Research Projects Agency (DARPA).
“Our team’s goal is to build a small laser-based bioagent warning system for use in buildings or homes or for troops to carry in their backpacks in the field,” said principal investigator Arto Nurmikko, professor of engineering and physics at Brown. “The device would be lightweight, quite possibly a small box, and lend itself to large-scale production.”
Last year’s anthrax attacks underscore the need for a “bioterrorism alarm system to mimic the concept of a smoke alarm,” said Nurmikko. “A bioagent detector would rapidly note an increase in airborne particles of biological origin, which is the ‘smoke’ in this case. This would allow investigators to activate bioagent-specific diagnostic tools immediately. Without advance warning that a bioagent has been introduced, the damage may already be done.”
The research team includes co-principal investigator Noble Johnson and colleagues at the Palo Alto Research Center (PARC) and scientists from LumiLeds Lighting LLC (a joint venture of Agilent Technologies and Philips Electronics), Metro Engineering Inc., the University of Texas–Austin and Yale University. During the next four years, the researchers propose to develop a bright and highly efficient semiconductor source of ultraviolet light (UV) composed of materials the size of sand grains. A lightweight box-like structure, perhaps no bigger than a soda can would contain the light emitter and miniaturized optical diagnostic components.
In use, a stream of ambient air – including dust, smoke, pollen and other pollutants – would flow into the box and through a UV beam, which would trigger a fluorescent emission. The device would read that emission and identify each particle by its spectroscopic “fingerprint.” The device would sound an alarm when the UV beam struck an increasing number of particles of biological origin such as anthrax.
This approach to bioagent detection is not fundamentally new, but the scientists will try to improve the technology of biodetection. Current laser-based systems for biological detection are large (often driven around in trucks) and expensive and require large amounts of electricity.
“Fluorescent emission gives us the ability to say that something with certain biological building blocks is present,” Nurmikko said. “To access the fluorescence requires deep UV radiation. The sources for such radiation are what we plan to use to create this warning system.”
The typical anthrax spore is about 1/10 the diameter of a human hair. To create a “snapshot” or “optical fingerprint” for such spores, the researchers plan to calibrate their device using closely related, but harmless biological agents.
The team faces formidable engineering challenges. Their light source concept is based on a new class of semiconductor materials called nitride semiconductors that will be atomically structured for emission in the UV. While semiconductor red and infrared light emitters are commonplace in applications from DVD players to automobile taillights, semiconductor light emitters in the UV are not an available technology.
“We have to extend the materials and device technology into the UV range,” Nurmikko said. “It’s a tough problem because we are pushing extremely difficult types of materials into a whole different realm, both in terms of controlling their quality at the atomic level and for extracting the UV radiation from the device.” Recent work by the team, including experiments at Brown, used new approaches to advance semiconductor emitters in the near-UV color range.
“Blue and violet semiconductor light emitters are now commercially available,” Nurmikko said. “Although the jump to UV presents scientific and technical challenges, their extension is possible but requires much scientific innovation. In principle we think we can create a grain of sand-sized UV source of light that operates at a high level of efficiency and brightness.”
The research team represents a range of expertise. LumiLeds Lighting, for example, is a leader in manufacturing high-brightness blue and other visible semiconductor light emitters, while Yale researchers have made advances in optical techniques for bioparticle detection.
Besides the core effort to develop a compact UV light source, the team will confront the challenges of “particle size and shape collection, manipulation, identification and calibration,” Nurmikko said. Meanwhile, device scientists will work to build a lightweight box to house the system and will determine how to mass manufacture a final product, he said.
“All of this will have to merge to fit the constraints of a compact bioagent warning system,” he said. “Given the security circumstance we have today, we think it is an important first step to being able to rapidly warn about the possible presence of airborne biological agents and eventually to identify them as well.”