Nanotechnology-enabled detection of landmines with the naked eye

Researchers at the University of Connecticut have developed a device that makes the location of buried landmines and other hidden explosive devices visible to the naked eye. Colin Poitras in his May 4, 0212 posting on the University of Connecticut website provides some background information about landmines and their detection,

Each year, as many as 25,000 people are maimed or killed by landmines around the world, including large numbers of civilians.

While landmines are inexpensive to produce – about $3-$30 each, depending on the model – finding and clearing them can cost as much as $1,000 per mine. It is a slow and deliberative process. Specially trained dogs are the gold standard, but they can be distracted by larger mine fields and eventually tire. Metal detectors are good, but they are often too sensitive, causing lengthy and expensive delays for the removal of an object that may turn out to be merely a buried tin can.

A UConn chemical engineering doctoral student hopes to help. Ying Wang, working in conjunction with her advisor, associate professor Yu Lei, has developed a prototype portable sensing system that can be used to detect hidden explosives like landmines accurately, efficiently, and at little cost.

The Aug. 2, 2012 news item on Nanowerk provides some information about the device ,

A chemical sensing system developed by engineers at the University of Connecticut is believed to be the first of its kind capable of detecting vapors from buried landmines and other explosive devices with the naked eye rather than advanced scientific instrumentation.

The research was first reported in the May 11, 2012 online edition of Advanced Functional Materials.

The key to the system is a fluorescent nanofiberous film that can detect ultra-trace levels of explosive vapors and buried explosives when applied to an area where explosives are suspected. A chemical reaction marking the location of the explosive device occurs when the film is exposed to handheld ultraviolet light.

Detection of buried explosives. (Image courtesy of Ying Wang) Downloaded from the University of Connecticut website:

The Aug. 2, 2012 news item on e! Science News provides additional detail about this detection system,

The system can detect nitroaromatics such as those found in TNT and 2,4-DNT (the military’s primary explosive and the principle components in landmines) as well as the elements used in harder to detect plastic explosives such as HMX, RDX, Tetryl, and PETN. The ultra-sensitive system can detect elements at levels as low as 10 parts per billion (TNT), 74 parts per trillion (Tetryl), 5 ppt (RDX), 7 ppt (PETN) and 0.1 ppt (HMX) released from one billionth of a gram of explosive residue.

If there is no explosive vapor present, the recyclable film retains a bright fluorescent cyan blue color when exposed to ultraviolet light. If explosive molecules are present, the fluorescence is quenched and a dark circle identifying the threat forms on the film within minutes.

“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.”

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.

Poitras’ posting notes the researchers have teamed with a landmine removal company (Note: I have removed some links),

One of the world’s top private landmine clearing companies, located in South Sudan, is currently working with Lei and Wang in arranging a large-scale field test. The results of the field test could be of interest to the United Nations, which has worked to make war zones plagued by old landmines safer through its United Nations Mine Action Service. It is estimated that there are about 110 million active landmines lurking underground in 64 countries across the globe. The mines not only threaten people’s lives, they can paralyze communities by limiting the use of land for farming and roads for trade.

“When I started working with landmines, I was thrilled,” says Wang, who received her bachelor’s degree in chemical engineering from Xiamen University in China in 2004 and her master’s degree in biochemical engineering from Xiamen University in 2007. “I knew this would be a really good application of our work. It can save lives.”

Wang and Lei are currently working with UConn’s Center for Science and Technology Commercialization (CSTC) in obtaining a U.S. patent for their explosive detection systems.

I last wrote about landmine detection systems in an Aug. 22, 2011 posting which centered on an ‘ultra’ portable system.

There are a number of ‘landmine’ programmes, I found these two: United Nations Mine Action Service, aka, E-MINE: Electronic Mine Information Network and the United Nations Association of the United States of America Adopt-A-Minefield Program.

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