Laser sniffs out hidden explosives from a distance

A British team has developed a low-cost laser that can detect hidden explosives from a much greater distance than existing devices.

Developed by University of St Andrews physicists, it can trace the vapour emitted from explosives such as TNT at extremely low concentrations – less than ten parts per billion.

The technology could be used to improve airport security, and also help detect landmines and roadside bombs which emit dilute clouds of vapor into the air. It’s relatively low-cost, since the plastic, polyfluorene, is widely used in plastic electronics.

Using a thin film of polyfluorene, a light-emitting plastic, the team created a laser that dims within seconds when it comes into contact with even the tiniest emission of vapour. It can be reset by a blast of nitrogen gas.

“Floating above a landmine in Iraq or Afghanistan, there’s a very weak, dilute cloud of vapors of explosive molecules that the bomb is made from,” said Dr Graham Turnbull.

“We have shown that our lasers can rapidly sense these TNT-like molecules, frequently used in explosives, at extremely low concentrations.”

The team says the laser could be built into a remotely-controlled robotic device that could be despatched into a minefield, looking for vapour clouds.

The research is published in Advanced Functional Materials.