Nurmikko leads effort to make smoke alarm for anthrax

DARPA award of $8.4 million will fund researchers' efforts 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.

by Scott J. Turner

It’s a sign of the times. A nationwide team of researchers led by Arto Nurmikko, professor of engineering and physics, recently received $8.4 million to create a compact warning system for airborne biological agents such as anthrax. The award comes from the Defense Advanced Research Projects Agency.

“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 Nurmikko. “The device would be lightweight, quite possibly a small box, and lend itself to large-scale production.”

Last year's anthrax attacks underscore the urgent need for a “bioterrorism alarm system to mimic the concept of a smoke alarm,” said Nurmikko.

“A bio-agent detector would rapidly note an increase in airborne particles of biological origin, which is the ‘smoke’ in this case,” he said. 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 team includes investigators at three companies and three universities. Over the next four years, they propose to develop a bright, 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 would flow into the box, which typically would include dust, smoke, pollen and other pollutants. The device would read and identify light emitted from each particle. It would do so by fingerprinting spectroscopically (forming the light into spectra for study) the particle’s fluorescence emission triggered by its intersection with the beam emanating from the ultra-compact UV light source. The device would sound an alarm when the UV beam struck an increased number of particles of biological origin such as anthrax.

This overall approach to bio-agent detection is not new. But the scientists hope to improve early-stage technology in bio-detection. Current laser-based systems to detect use of biological agents are large (often mounted in trucks), expensive and require significant support services, including large amounts of electricity.

“We more or less know what is in ambient air, but this fluorescent emission gives you the ability to say that something with certain biological building blocks is present,” Nurmikko said. “To access the fluorescence requires deep UV radiation, and 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 hair strand. To create a “snapshot” or “optical fingerprint” for such spores, the researchers plan to calibrate their device using closely related but harmless biological agents.