Light-emitting film shows traces of explosives

The new spray film, developed by University of California, San Diego chemists, will be the basis of portable devices capable of rapidly identifying fingerprints contaminated by nitrogen-based explosives.

A damiamit explosive handprint darkens in the light of the explosive gel. (Photo: Jason Sanchez / UCSD)

Dirty fingerprints leave the film on the film, which turns blue under ultraviolet light. One of these films can distinguish different types of chemical explosives, a substance that can provide evidence to help solve or prevent a crime.

A recent episode in the US television drama 'Investigating the Case', which features Miami, shows off a technology that could link fingerprints to a camcorder with a bomb. used in a bank robbery, help reveal the motives of the robbery. In fact, the RedXDefense security company has developed a technology-based kit that security personnel can use with little training.

Fluorescent polymer-based detection was developed at the University of California, San Diego by chemistry and chemistry professor William Trogler and graduate student Jason Sanchez. 'This is an intuitive detection method without the need for a scientist to participate,' said teacher Trogler.

Polymer emits blue light when excited by ultraviolet radiation.

Because fluorescent polymers are very bright, there is no need for a special device to read the results. Only a very thin film is sprayed onto the suspect surface to see if there is a presence of dangerous chemicals. Just a single layer of polymer, about a thousandth of a gram, is sufficient to detect small doses of some explosives, to a few trillionths of a gram (picogram) on a half-foot diameter surface.

These films are also directly attached to potentially contaminated surfaces, making them more sensitive than previous methods based primarily on capturing molecules that escape into the air.

Detection can be performed quickly within 30 seconds, indicating fingerprints are suspected immediately after the solution is dry.

Trogler's team is currently developing a similar system to detect peroxide-based explosives.