Engineers at the University of Connecticut have developed a chemical sensing device that — using film, rather than advanced instrumentation — can “see” vapors from buried landmines and other explosive devices.
The innovation of the device is found in the fluorescent nanofiberous film that can detect ultra-trace levels of vapors from explosive materials, reports e! Science News. A chemical reaction marking the location of the explosives occurs when the film is exposed to handheld ultraviolet light.
The device can detect vapors such as those found in TNT and 2,4-DNT (the military’s primary explosive and the principle component found in landmines) and elements used in harder-to-detect plastic explosives, such as HMX, RDX, Tetryl, and PETN. The engineers claim that the system can detect TNT elements as low as 10 parts per trillion (ppt), Tetryl elements as low as 5 ppt, PETN as low as 7 ppt, and HMX as low as 0.1 ppt.
“Our initial results have been very promising,” says UConn Dr. Ying Wang, who developed the system as a chemical engineering doctoral student working under the supervision of UConn Associate Engineering Professor Yu Lei. “We are now in the process of arranging a large-scale field test in Sweden.”
The research was reported in a May online issue of Advanced Functional Materials. The article at e! Science News explains further how the device works:
Rather than using sophisticated chemical modifications or costly synthetic polymers in preparing the sensing material, UConn scientists prepared their ultra-thin film by simply electrospinning pyrene with polystyrene in the presence of an organic salt (tetrabutylammonium hexafluorophosphate or TBAH). This resulted in a highly porous nanofiberous membrane that absorbs explosive vapors at ultra-trace levels quickly and reliably. The film also has excellent sensitivity against common interferences such as ammonium nitrate and inorganic nitrates. Initial vapor detection took place within seconds with more than 90 percent fluorescent quenching efficiency within six minutes.
The team also has developed a chemical test for detecting TNT in water and other liquids. The application could be used to test for groundwater contamination in areas where explosives were used in construction, or to detect potential terrorist threats from explosives in airports.
That real-time sensor can detect TNT concentrations as low as 33 parts per billion. That sensitivity is like finding a drop of explosive material in 20 Olympic-sized swimming pools.
“Our new sensor based on a recently developed fluorescent polymer for explosives in aqueous samples has two sensing mechanisms in one sensing material, which is very unique,” says Lei. “The sensor can easily be incorporated into a paper test strip similar to those used for pregnancy tests, which means it can be produced and used at a very low cost.”
Source: “New Chemical Sensor Makes Finding Landmines and Buried IEDs Easier,” e! Science News, 8/2/12
Dale McGeehon has been a journalist and editor for more than 25 years, covering chemical regulation and testing for Pesticides and Toxic Chemical News and innovations in material sciences for the National Technology Transfer Center. His writing credits include Omni and College Park magazines and The New York Times.