Spray-on material can detect and neutralise explosives

Researchers have described the development and successful initial tests of a spray-on material that both detects and neutralises explosives.

"This stuff is going to be used anywhere terrorist explosives are used, including battlefields, airports, and subways," said study leader Allen Apblett.

"It's going to save lives."

The material is a type of ink made of tiny metallic oxide nanoparticles - so small that 50,000 could fit inside the diameter of a single human hair.

The ink changes colour, from dark blue to pale yellow or clear, in the presence of explosives. It also changes from a metallic conductor to a non-conducting material, making electronic sensing also possible.

This colour-change feature allows the material to work as a sensor for quickly detecting the presence of vapors produced by explosives, Apblett said. 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 use the sensors as part of stationary monitoring devices. The sensors could even be engineered into jewellery and cell phones, the scientist added.

The same color-changing material can also serve as an explosives neutraliser. Firefighters and bomb squad technicians could spray the ink onto bombs or suspicious packages until the color change indicates that the devices are no longer a threat, Apblett said. Technicians could also dump the explosives into vats containing the ink to neutralise them.

The new ink provides a quick way to detect and test these explosives, which might be hidden in clothing, food, and beverages. The ink contains nanoparticles of a compound of molybdenum, a metal used in a wide variety of applications including missile and aircraft parts. The dark blue ink reacts with the peroxide explosives and turns yellow or clear.

"This does a really good job of neutralising terrorists' explosives," said Apblett, a chemist at Oklahoma State University in Stillwater, Okla.

They reported on the new ink-like explosive detector/neutraliser at the 241st National Meeting and Exposition of the American Chemical Society (ACS).