Researchers at Sandia national laboratory have developed a toxic-gas sensor that is smaller, faster, and more reliable than any other on the market. It ideal for portable detectors for sniffing out chemical weapons. Better miniature sensors can also rapidly detect airborne toxins, providing key information to help emergency personnel respond safely and effectively to an incident.
Chemical identification typically involves collecting a sample at the scene of a chemical release and bringing it back to a room full of equipment operated by trained technicians. The machines sift through a sample of various gases and weigh the molecules to determine their identities. And although there are portable versions of these instruments, known as mass spectrometers, they are less sensitive than their lab-based counterparts.
For more than 20 years, researchers at Sandia National Laboratories have been working to avoid the performance penalty for portable gas detection. Their sensors employ a technique called gas chromatography, or GC for short.
Briefcase-sized instruments from Sandia have sniffed for nerve and blister agents continuously for 22 months in the Boston subway system without a false alarm. Sensors about the size of an AA battery can detect a compound in sweat that signals smuggled humans. Handheld gas sensor systems can also monitor crop health by identifying gases plants release when stressed by drought or sickness.
Now, Joshua Whiting, an analytical chemist at Sandia, and his colleagues have shrunk their sensor to about the size of a dollar bill while also increasing its performance. The device separates a gas sample twice and analyzes both in less than 10 sec. The extra separation step reduces interference from solvents, cleaners, and diesel fuel that could also be in the air during a chemical weapons release. Less interference also means the signal for detected target compounds is more reliable. “The false alarm rate for this gas sensor is even lower than before,” Whiting said.
The researchers used the sensor to identify each ingredient of a 29-compound mixture in seven seconds. The device also detected compounds that simulate mustard gas and phosphonate-based nerve agents during 40 days of continuous operation.
“Rapid analysis gives responders time to learn about exposure to a specific toxin in time for people to take personal precautions, evacuate an area, and mitigate potential damage,” Whiting says. Key to that rapid analysis is a pressure valve in the sensor that controls how quickly gases flow through each separation step. Controlling this flow with pressure lets the sensor use less energy than similar temperature-controlled systems.
Energy efficiency, combined with reliable detection in an increasingly small package, sets the researchers up for the next phase of the project: building a fully portable analytical device with chemical separation, selective detection, and computerized analysis that performs at least as well as lab-based gear.
The majority of the funding for the micro-gas sensing research has come from the Defense Advanced Research Projects Agency (DARPA) and the Defense Threat Reduction Agency (DTRA), along with some funding from Sandia’s Laboratory Directed Research and Development program. The researchers are now seeking funding to build the device and incorporate additional functions that will enable it to compete with lab-scale equipment.