May 27, 2008 Scientists at the University of California, San Diego, have developed a spray-on explosive detector that glows blue under UV light in the presence of nitrogen-containing explosives. The silafluorene-fluorene copolymer is sensitive enough to detect just a billionth of a gram of explosive.
The polymer detects particles instead of vapor, making it accurate enough to act as a switchable sensor with picogram (10-15g) detection limits – the first polymer of its kind to do so. After further exposure, nitrate esters like trinitroglycerin will change color to a green-yellow, with nitroaromatic explosives like TNT remaining blue, increasing its usefulness to investigators and forensic analysts.
The technology is currently being commercially produced by RedXDefense. The researchers are now working on a similar system to detect peroxide-based explosives, with hopes to investigate perchlorates and organic nitrates further down the road.