Laser Sensor Can See Explosives' Vapor Trails Even at Extremely Low Concentrations

Detecting explosives, whether they're tucked into the roadside rubbish on a narrow street in Helmand Province or stashed in someone's undergarments at the airport, can be difficult to do. But UK researchers have developed a potent new tool for sniffing out combustible contraband by creating a novel laser mechanism that can sense explosive molecules at concentrations below 10 parts per billion.

The new sensor tech relies on "pumping" a specific type of plastic called polyfluorene with photons. When polyfluorene is bombarded with light, it emits laser light. Molecules given off by TNT and similar explosives often present in improvised bombs react with that "plastic laser," interfering with the light it emits to a detectable degree. That interference suggests the presence of explosives in the very near vicinity.

Since the laser sensors have to be present more or less right on top of the explosives the tech is not ideal for human use, but it could help bomb disposal robots sniff out hidden threats when sweeping an area for explosives. The sensors could also be placed at security checkpoints and luggage screening areas in airports to seek out molecules that are the telltale signs of hidden combustibles.

The technology could also aid in the peaceful removal of land mines in regions like Southeast Asia that are still trying to remove ordnance left behind from decades-ago military conflicts. But perhaps best of all: the key ingredient in the sensors is plastic, so they should be relatively cheap to produce. Cheap is ideal, of course, for a product designed specifically to go where explosives are.