New sensor can detect tiny quantities of explosives

Researchers have developed a new sensor that can detect even tiny quantities of explosives with the use of light and special glass fibres.
The novel optical fibre sensor can detect explosives in concentrations as low as 6.3 ppm (parts per million) in only a few minutes.
"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 of Adelaide'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," Tsiminis said.
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 is reduced by the presence of explosives.

Three minute holes at the core of specially manufactured optical fibres are coated with the plastic or polymer material in a thin layer. The explosives sample is drawn up the holes in the fibre 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.
"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," Tsiminis said.
The study was published in the journal Sensors and Actuators B: Chemical.