Using Fluorescent Light To Detect Bombs

Scientists from Australia and China have used light and the chemistry of explosive compounds to build a promising new type of explosives sensor.

AsianScientist (May 22, 2014) – Scientists have developed a sensor that can detect tiny quantities of explosives using fluorescent light and special glass fibers, offering a sensitive means of bomb detection. The research has been published in the journal Sensors and Actuators B: Chemical.

“Traditionally, explosives detection has involved looking for metals that encase them such as land mines. 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,” explained Dr. Georgios Tsiminis from the University of Adelaide.

Quenching is a process whereby the fluorescence intensity of light is reduced. Due to their electron deficiency, nitroaromatics commonly found in explosives such as trinitrotoluene (TNT), dinitrotoluene (DNT) and picric acid (PA) are highly suitable florescence quenchers.

By exploiting the quenching ability of explosive compounds, Tsiminis and his team built an optical fiber sensor able to detect explosives in concentrations as low as 6.3 ppm (parts per million).

The researchers used a plastic material which emits red light when illuminated with green laser light. This fluorescent plastic was then used to coat specially manufactured optical fibers with tiny holes at their core. For testing, the explosives sample is drawn up the holes of the fiber by capillary action. If explosive materials are present, they quench the fluorescence and a reduced amount of red light is emitted.

“This has high sensitivity and we can detect tiny quantities of an explosive in a small sample,” said Tsiminis of the sensor. “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.”

The article can be found at: Chu et al. (2014) Explosives detection by fluorescence quenching of conjugated polymers in suspended core optical fibers.

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Source: The University of Adelaide; Photo: Douglas Muth/CC/Flickr.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

Alan Aw is a maths enthusiast who likes sharing the fun and beauty of science with others. Besides reading, he enjoys running, badminton, and listening to (and occasionally playing) Bach or Zez Confrey.

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