The new devices, however, are "self-sensing," consume very little power, and many micro-cantilevers can be used simultaneously.
Mechanical Sniffer Dogs
The capture of explosive particles requires special air handling.
"Explosives have very low vapor pressures, and don't give off a lot of molecules at room temperature," said Adams. "So what you need to do is shake up a few particles, heat them up, get a hold of a couple of particles, and run their vapor by the sensors."
An air conditioning system used at the front entrance of a building could help dislodge the particles and drive them towards an array of distributed sensors.
"The technology could be used anywhere you want to know if there's someone moving around with explosives, like in countries where there are constant acts of terrorism," said Adams.
He says the sensors could be mass-produced and, therefore, cost-effective. In the future, they could replace dogs as the primary detectors of explosives. "Dogs can not be strapped to packages, ventilation systems or airport walls," he said. "Dogs are complex animals that require training. They need naps, they need to eat, and they can only be at one place at one time. You can't train a dog and then multiply it by a million and have copies communicating with each other over a building network. You can do this with silicon and signal processing technology."
Expanding the Technology
The technology is still at a very early stage. But the sensors have already been able to detect the deflagration, or small explosion, of as little as 70 picograms of TNT. (A picogram equals one trillionth of a gram.)
This limit of detection is the same as that of an improved version of something called ion-mobility mass-spectrometry technology that is now used in airports. According to his calculations, Adams should be able to further increase the sensitivity of his micro-sensors by a thousand times.
So far, the new technology only works on TNT, but the sensors could also be modified to detect other explosive molecules. Perhaps a device could be developed to locate landmines.
"The technology holds great promise," said Adams. "This could be a powerful explosives detection technology and on the market in three to five years."
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