December 7, 2009
Detection by a Nose: APL Researchers Look to Copy Canine "Sniffer"
A dog's nose, with its thousands of olfactory receptors, is one of the best chemical detection "sniffers" in military and police circles. That's why an APL Homeland Protection Business Areateam is working with the Defense Advanced Research Projects Agency (DARPA) on its RealNose program, which aims to construct a sensor that would operate like (and as well as) a dog's nose. The sensor will eventually be integrated into a system that could simultaneously detect more than 20 chemicals.
The team recently completed the first part of the project, determining the limits of canine detection for a variety of nontoxic, nonhazardous chemicals, compounds, and odorants that dogs would normally search for in the field or when training. The tests included five dogs provided by Castle's K9, a law-enforcement canine training firm in Pennsylvania. A staff member in the National Security Technology Department used her experience with the Customs and Border Protection canine program to develop training aids and protocols for the tests.
The team built a vapor generation and control system that produced a variety of scents at various concentrations. Ten different compounds were tested to determine how little of each compound the dogs could recognize. The test equipment was housed behind a six-sided structure, with a cone on each wall through which each vapor was sent, one at a time. Starting at random locations around the structure, a handler would allow a dog to walk around it, no more than twice, and sniff each cone. When a dog correctly detected the target scent, the team recorded the concentration and the handler rewarded the dog.
The DARPA-specified chemicals used in the test included cyclohexanone, a residual (nonexplosive) solvent found in the plastic explosive C4; methyl benzoate, a product broken down in cocaine that is often used as a training aid for drug-sniffing dogs; ethyl vanillin, an artificial vanilla; limonene, which is often found in cleaning solvents; and amyl acetate, which smells like bananas.
Working Like a Dog
Although Ares, Max, Kika, Murphy, and Nellie may have initially looked and acted like ordinary family pets, the team realized that the command "Find it!" turned the dogs into focused, hard-working searchers.
"Dogs are very adept at picking out odor amongst a lot of clutter or confounders," says Michael Wagner, program manager for RealNose. "During our tests, we could see the dogs constantly learning and getting better at detection. As cognitive beings, they think, learn, and cheat if they can to get their reward, but our tests were designed to keep things random and prevent them from cheating."
Having determined the detection limits and evaluation standards for the next test phase, the team is now building and characterizing the RealNose test equipment and structure in an aerosol chamber. The team will evaluate the nose-like sensors being developed by other organizations to see whether their measurements are as good as the canines'. Tests began last summer and will wrap up by the end of the year.
Phase 2 of the project, which starts in 2010, will require the sensors to detect odorants masked in multiple chemicals and possibly aerosols. "If things continue successfully," Wagner says, "the end goal is to wrap up with a prototype device by 2012 that could be transitioned to industry and used anywhere you could use a dog or in areas that might be too dangerous for one, such as searching rubble after an earthquake if toxic chemicals are present."
The potential uses of these sensors are wide-ranging, Wagner says. It might someday be possible to fly olfactory receptors on an unmanned aerial vehicle to detect chemical agents associated with weapons of mass destruction—a mission impossible for even the keenest four-legged agent.