Breakthroughs sought in Chem-Bio sensors.

• Author: Tiron, Roxana
• Position: Georgia Tech Research Institute developing new technology - Brief Article

A shoebox-sized optical sensor that measures light speed and patterns is being tested as a possible detector of chemical or biological agents. The technology has the potential to make the detection of agents easier and faster, scientists said.

The Georgia Tech Research Institute is developing this technology under a U.S. Marine Corps contract, which allotted approximately $300,000 a year for the two-year old program. But the system will require several million dollars in additional funding in order to be deployable in at least 18 months, said Thomas Bevan, director of the Center for Emergency Response Technology, Instruction and Policy (CERTIP) at the institute. CERTIP is a public-private partnership focusing on emergency response and consequence management research.

The sensor consists of a laser light source, a planar wave-guide and a detector for monitoring light velocity changes produced by a chemical reaction, taking place on the wave-guide.

The wave-guide is a two-centimeter piece of glass, while the laser light goes through the glass slide creating two beams. The beams are steered at each other, thus creating an interference pattern, explained Bevan. "The laser produces coherent light that is the same color--all the photons are marching along in unison down these two channels," he said.

One of the light channels is a reference channel exposed to the atmosphere and water, while the second channel has a "particular kind of chemistry painted and is designed to have a chemical reaction to things we want to detect," Bevan said.

When the chemical agent comes into contact with the other chemical on the test channel, the speed of light changes and the "interference pattern starts moving, because the light arrives later or earlier," said Bevan. A regular web camera is at the spot where the interference pattern conveys. It records the results, essentially measuring the shifts in the light.

"The detection is instantaneous," said Bevan. "The only limiting factor is how fast the chemical gets to the surface of the test drip."

For biological detection, the steps are fairly similar to the chemical procedure. The detection measures the number of colonies formed per unit of fluid. According to Bevan, the sensor can measure a couple of hundred colonies forming per milliliter, "so it is pretty sensitive," he said.

Georgia Tech scientists are working on tuning the sensor to anthrax. "It entails getting an antibody, which you can buy commercially and...