By Andy Choi
Researchers from the TU Darmstadt have collaborated with material scientists from the RhineMain Polytechnic, to develop an ultra sensitive nanosensor, which has the ability to detect small amounts of Pentaerythritol tetranitrate (PETN). PETN is a high-explosive chemical compound which is used by terrorists during numerous attacks carried out on commercial aircraft.
Currently, PETN could be detected only by using an ion-mobility spectrometer and wipe tests which are very time consuming, and hence are used only at airports for spot-checking. Dogs and airport scanners find it very difficult to detect PETN as it less volatile and disperses only a very small number of molecules into the air. PETN’s explosive nature could destroy a passenger car of medium size with just a few grams.
The new nanosensor could detect the presence of even one single molecule of PETN, in the midst of ten billion air molecules. According to Mario Boehme, when the PETN molecule gets into the nanotube of the sensor, the nitro groups which are present in the PETN remain stuck on the surface and thus alter the electrical conductivity which is then identified by electronic instrumentation.
Just by conducting ambient air across the sensor, the new sensor can detect the presence of PETN. Boehme reveals that the traditional X-ray machines and the metal detectors at security checkpoints at the airports could be fitted with the new sensor and also a device for inducting air. This would help them to do a discreet check of all the passengers and their luggage for explosives without wasting time. Another method would be to use a hand-held device very much like a table vacuum cleaner for checking individual passengers. Boehme also believes that as these sensors were compact and low cost so they could be used even in sports events and other places for security checks.