Explosives detectors strive to surpass bomb-sniffing dogs

New York Times : Dogs’ keen sense of smell has proven to be successful at detecting bombs, but live animals require significant training and handling and cannot function continuously. So researchers have been working on devices that can sense explosive particles as well as dogs can. Flir Systems in the US, whose detectors are already being used in the military, use thin films of fluorescent polymers. The films emit visible light when exposed to UV rays, but molecules of TNT stop the fluorescence. Another approach, being developed by Denis Spitzer and colleagues in France, uses microcantilevers composed of slivers of silicon. Fixed at one end, the slivers are made to vibrate like a diving board; as the cantilever captures molecules of explosives, the increased mass alters the vibration rate. Despite all the advances, however, “dogs still reign supreme,” writes Henry Fountain for the New York Times.