Explosive sniffer

An artificial “nose” is being trained to detect buried landmines. David Walt
and his colleagues at Tufts University in Medford, Massachusetts, are teaching a
portable device to identify 2,4-dinitrotoluene (DNT), a vapour given off as TNT
breaks down in landmines (Environmental Science and Technology, vol 35,
p 3193). Walt’s device relies on seven polymer-based sensors containing dyes
that fluoresce when they absorb organic molecules. Working together, the sensors
yield a “fingerprint” that is unique to each chemical. Walt’s team programs the
detector’s computers to recognise DNT. “Once you’ve trained it, the pattern is
stored in the computer memory…