Spray-on material detects and disarms explosives

The material is a type of ink that contains nanoparticles of a compound of molybdenum. The ink changes colour, from dark blue to pale yellow or clear, in the presence of explosives.

This colour-change feature allows the material to work as a sensor for quickly detecting the presence of vapours produced by explosives, according to associate professor of chemistry Allen Apblett from Oklahoma State University.

Apblett said that soldiers or firefighters could wear the sensors as badges on their uniforms or use them as paper-based test strips. Airports, subways and other facilities could also use the sensors as part of stationary monitoring devices.

The same colour-changing material can also neutralise explosives. In laboratory studies, the scientists showed that they could add the material to TATP or HMTD explosives and render them ineffective. As such, bomb-squad technicians could spray the ink onto bombs or suspicious packages until the colour change indicated that the devices were no longer a threat. Explosives could also be dumped into vats containing the ink to neutralise them.

Since the ink also changes from a metallic conductor to a non-conducting material, it could be used in an electronic sensor where it could detect TATP vapours at levels as low as a 50 parts per million within 30 seconds.

The material can also improve safety at laboratories that use explosive chemicals. Recently, Apblett developed pellets containing the ink that can be added to laboratory solvents to prevent the build-up of levels of dangerous peroxides, which can cause accidental explosions. The colour-changing feature helps the users of the solvents to know that they are safe.

Apblett and his colleagues have now founded a company called XploSafe to develop and market the material. They hope to see the explosive-detecting ink used in airports in as little as a year.