Sensor can Detect Explosives

Wednesday, May 14, 2014 @ 06:05 PM gHale

The fight against terrorism is ongoing, but a new sensor could help detect tiny quantities of explosives with the use of light and special glass fibers.

A novel optical fiber sensor can detect explosives in concentrations as low as 6.3 ppm (parts per million) and requires an analysis time of only a few minutes, said researchers at the University of Adelaide.

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“Traditionally explosives detection has involved looking for metals that encase them such as in land mines,” said project leader Dr. Georgios Tsiminis, from the University’s Institute for Photonics and Advanced Sensing.

“In today’s world, however, homemade improvised explosive devices will often have no metal in them so we need to be able to detect the explosive material itself. This can be difficult as they often don’t interact with chemicals and we don’t want them near electricity in case they explode,” he said.

Instead, the researchers are using a plastic material which emits red light when illuminated with green laser light – and the amount of red light it emits ends up reduced by the presence of explosives.

Three minute holes at the core of specially manufactured optical fibers have a coating of plastic or polymer material in a thin layer. The explosives sample draws up the holes in the fiber by capillary action and the amount of red light emitted measured.

“This has high sensitivity and we can detect tiny quantities of an explosive in a small sample,” said Tsiminis, who is an Australian Research Council Super Science Fellow. “And not only do we know if explosives are there, we can quantify the amount of explosive by looking at how the light emission changes over time.”

Tsiminis said the sensor is ideal for forensics investigations to determine whether explosives have been present in a particular location. It’s inexpensive, quick and easy to use and could see use on site to detect trace amounts of explosive.

“What I like about this technology is that it has a lot of complicated physics underlying it, but it is really a very simple concept,” Tsiminis said.

“It also requires very little explosives present so it is very sensitive. So forensic investigators would be able to take swabs from various surfaces, place them in some organic solvent and, within a few minutes, know if there have been explosives present.”

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