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An artificial 鈥渘ose鈥� 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鈥檚 device relies on seven polymer-based sensors containing dyes
that fluoresce when they absorb organic molecules. Working together, the sensors
yield a 鈥渇ingerprint鈥� that is unique to each chemical. Walt鈥檚 team programs the
detector鈥檚 computers to recognise DNT. 鈥淥nce you鈥檝e trained it, the pattern is
stored in the computer memory and recognised in the same way as we recognise a
smell,鈥� says Walt.