Portable gas sensors have traditionally sacrificed performance for a smaller size. Sandia National Laboratory scientists have developed a gas sensor that reportedly does not sacrifice performance,
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 personnel. The machines sift through a sample of various gases and weigh the molecules to determine their identities. The portable versions of these instruments, known as mass spectrometers, are less sensitive than their lab-based counterparts.
Laboratories, examines a gas sensor that could be used
in a sensitive portable system to detect chemical weapons
or airborne toxins (Image source: Randy Montoya).
Briefcase-sized instruments from Sandia have sniffed for nerve and blister agents continuously for 22 months in the Boston subway 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 that plants release when stressed by drought or sickness.
Joshua Whiting, an analytical chemist at Sandia, and his colleagues shrunk their sensor to about the size of a dollar bill while also increasing the performance of the sensor. The system now separates a gas sample twice — yet performs an entire analysis in less than 10 seconds. 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.
In a paper recently published in Lab on a Chip, the researchers used the sensor to identify each ingredient of a 29-compound mixture in seven seconds. The system also reliably detected compounds that simulate mustard gas and phosphonate-based nerve agents during 40 days of continuous operation.