German scientists have devised a system which can point out terrorists by capturing the smell of explosives.
The artificial nose promises to make it much easier to detect the explosive triacetone triperoxide, reports New Scientist.
The device could be installed in the doorways of buses, trains and airports to sound an alarm if someone carrying TATP crosses the threshold.
The explosive can be made using easily obtainable domestic chemicals and has explosive power similar to TNT.
However, Siegfried Waldvogel, an organic chemist at the University of Bonn, Germany, said that TATP's high vapour pressure at ambient temperatures makes it hard to hide.
The vapour diffuses through materials such as plastic bags and into the surrounding air, but the current method for detecting it is time-consuming, as air samples have to be sent to a lab for tests.
Now, Waldvogel and his colleagues have developed a cheap detector that responds instantly to TATP in the atmosphere.
At its heart are three quartz rods, each 3 millimetres long and 40 micrometres wide, which are made to vibrate by applying an alternating voltage.
Any TATP in the air bonds to chemicals coating the rods, causing their resonant frequency to change.
Each rod is coated with a different chemical - a phenylene dendrimer, a cyclodextrin and sodium cholate - and each changes its rod's resonant frequency in a different way. It is the combination of three changes that reveals TATP's presence.
In tests, the device was able to discriminate between the explosive and similar gases, sensing it at levels of 1 part per million.
Explosives expert Sidney Alford of Alford Technologies in Chippenham, UK, said: "There could be an enormous demand for such a device. TATP is used both as a main charge and as a detonator in terrorist bombs, so even if it is only being used to initiate another explosive, you will still be able to sense it."
The study has been published in Sensors and Actuators B.