“Our initial results have been very promising,”
Engineers at the University of Connecticut (UConn) have developed a fluorescent nanofibrous film capable of detecting ultra-trace levels of explosive vapors from landmines and other buried explosive devices. In the presence of explosive molecules, the film’s fluorescence is suppressed when exposed to ultraviolet (UV) light. In this way, the lightweight film, which is similar to paper, could be rolled out over suspect areas to mark the location of explosive devices.
The ultra-thin film is cheaply and easily produced by electrospinning pyrene with polystyrene in the presence of an organic salt known as tetrabutylammonium hexafluorophosphate (TBAH). The team says the resulting nanofibrous membrane is highly porous and absorbs explosive vapors at ultra-trace levels quickly and reliably.
As well as detecting elements found in TNT and 2,4-DNT, which are the principle components in landmines, the film can also detect elements in harder to detect plastic explosives such as HMX, RDX, Tetryl, and PETN. It can detect elements from TNT at levels as low as 10 parts per billion, Tetryl at 74 parts per trillion (ppt), RDX at 5 ppt, PETN at 7 ppt, and HMX at 0.1 ppt, released from one billionth of a gram of explosive residue.
In the presence of explosive vapor, the recyclable film turns dark blue when exposed to UV light. The team says initial vapor detection takes place in seconds, with more than 90 percent fluorescent quenching efficiency occurring within six minutes.
While the system is still not as sensitive as a sniffer dog, which can detect explosives such as explosives at concentrations in the parts per quadrillion range, the researchers point out that dogs can get tired and also have difficulty differentiating between devices in dense minefields.
via Gizmag – Darren Quick
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