Breakthroughs sought in Chem-Bio sensors.

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 that causes a chemical reaction with the anthrax spore," Bevan pointed out. However, the institute does not hold any anthrax spores and the tests have to be taken to other labs.

"Sampling is still the toughest part," said Daniel Campbell, a senior research scientist at the institute. "The antibodies need aqueous solutions, so you have to do that in a water environment, that is you have to collect the samples and you have to have water solution on top of the wave guide."

There is also a special air collector that takes the air sample and concentrates it into a solution that also goes into the wave guide. "The time response is very quick--it takes less than a minute to get your answer," Campbell said. "But the collection schemes are more expensive than the instrument itself."

"We can discriminate better when we measure ...[a change in] the velocity of the light [and] the web cams have a much better detection capability," said Campbell. The technology can detect a whole array of agents, he added.

"In a one-by-two centimeter chip you can have something in the order of 75 sensors, so you can look for chemical and biological agents," said Bevan. "You can do pattern recognition across the two channels."

Right now, the box that houses the optic sensor is only six-by-four-by-three inches. "It is a lot of air in that box," said Campbell. The laser is a regular CD-player laser and the web cam is plugged to a laptop to read out the sensor. The wave-guide is made in-house, said Campbell. Altogether, the sensor would go for about $200 to $300. However, the Marine Corps requested that CERTIP choose a company to build an integrated detection system.

So far, Satcon, a Boston-based company has expressed interest in manufacturing the system, according to Campbell. "Everybody is talking about putting money in defense, but the money has nor appeared yet," he said. He said it would take approximately another million to integrate other elements into the box.

The method and technology used for this detection system are not new. They have been used in the environmental and food processing industries, for example, to detect salmonella, said Bevan.

The integrated-optic sensor eventually could function together with other technologies that could aid the military and first responders. One possibility is a medical reach-back system that can transmit vital patient information using a secure wireless local area network, said Bevan.

The system would transmit information on victims' symptoms and vital signs, so doctors in hospital emergency rooms can remotely assess the condition of the patients and order treatment.

The problem in Georgia and other states is that it is illegal for medical technicians to give chemical antidotes without a doctor's permission, Bevan said. In a chemical attack, there may not be enough time to get the required approval.

Researchers are now trying to make the system more portable. Additionally, Georgia Tech is working on a ChemBio Decision Aid software program--that can run on a personal digital assistant--to help first responders or emergency medical technicians determine the possible chemical or biological agent based on the victim's symptoms.

The program provides a checklist of symptoms to help them male their decisions. "Even if they [first responders] do not get a hold of medical personnel, they will have some knowledge in the Palm Pilot," said Bevan.

A situational awareness geographic information system tracks the location of people and biological and chemical agents in the field. GIS technology can create electronic maps that superimpose various types of information in layers over a common map.

The system could transmit information, such as blueprints and forecasts of containment plume dispersion from command centers to emergency personnel on the scene.