PETN nanosensor could improve explosives checks

Materials scientists at the TU Darmstadt have developed an extremely sensitive explosives sensor that is capable of detecting very slight traces of pentaerythritol tetranitrate (PETN).

To date, tests for PETN, a high-explosive chemical compound, are done by wipe tests and an ion-mobility spectrometer.

However, since conducting such tests involves considerable time and effort, it is employed at airports for spot-checking only.

Airport scanners and sniffer dogs are said to have difficulties detecting PETN, since PETN is only slightly volatile and releases only small numbers of molecules into the ambient air.

Working in collaboration with the Rhinemain Polytechnic, scientists at the TU Darmstadt recently developed a nanosensor that is capable of detecting a single PETN molecule among 10 billion air molecules.

Explaining the new type of explosive detector’s operation, Dip-Ing Mario Boehme said: ‘If a PETN molecule enters the sensor’s nanotube, the nitro groups characteristic of PETN adhere to its surface and change its electrical conductivity — and that change may be detected by electronic instrumentation.’

In order to detect PETN using the new sensor, all that is necessary is conducting ambient air across the sensor.

‘One possibility would be equipping the conventional metal detectors and X-ray machines employed at airport security checkpoints with the new sensor and a device for inducting air,’ said Boehme.

That approach would enable discreet checks of all passengers and their luggage for explosives without spending more time on the process.

Boehme added that another possibility would be to utilise a hand-held device similar to a table vacuum cleaner that would allow all passengers to be checked individually.

Since the sensors are extremely small and inexpensive to manufacture, he can also envision employing them at sports events or in other types of security checks.

He and his research associates are currently seeking industrial collaboration partners.