Lev Bely, 27.06.2012 22:21
Bombs and other explosives leave around an invisible chemical trace. In airports and other common places these microparticles, which dangling in the air, are detected by security dogs which has a special, trained nose. Yet such dogs are rather expensive to hold and train, they get tired soon during their service, what's apparently unsafe since a weary dog may miss a bomb, sooner or later.
A new method of detecting the chemical dust of TNT (trinitrotoluene) or explosives of the kind came from other perfect sniffers, namely, silk moth males (Bombyx mori) and their gorgeous feathery antennae. The latter are in fact the leading organ in moth perception since the very antennae catch single pheromone molecules what informs male of where should he seek for a female. Antennae consist of lots of hairs which permanently vibrating at a regular frequency. As the pheromone molecule gets on a hair, the vibration changes and a male receives the sensory signal.
A new detector works in a similar way. It's covered with titanium dioxide nanotubes which TNT molecules get “glued” to. Just as the hairs of the moth antennae, nanotubes are fixed to a stalk with only one end, therefore they continuously and steadily waff, in a way, say, springboards do.
Albeit this process immediately changes its course once the detector “catches sight” of even the slightest amount of TNT dust at close distance. At the moment the quivering nanotube drags in a molecule of explosive, the vibration frequency changes and the sensory system of the detector is signalled of that there is an explosive close by.
Altogether, the titanium dioxide coating and vibrating nanopores provide a highly sensitive system which is capable to catch up to one part per trillion of TNT and similar explosives. “The system answers in real time so you can put the sensors in luggage rooms at the airport,” says Denis Spitzer, the author of the system. His research was partially funded by the French defence procurement agency, Spitzer as well offers the device to militaries.
Further versions of the detector will be replenished with different kinds of bristles so as it could catch at a time molecules of various explosives. “A first step will be to make it even more sensitive than it is now,” says Spitzer.
One of the significant advantages of the new device is its immediate reaction, though Spitzer notes that the detector still has to be tested for its ability to spot explosives from far away. “A version of the detector made with different materials could detect tiny amounts of chemicals in water as well,” Spitzer says.
Photo: Bombyx mori, (Walter S. Leal), http://www.chm.bris.ac.uk
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