The Sciences

Crime-Fighting Polymer Reads Letters in Sealed Envelopes

DiscoblogBy Nina BaiNov 15, 2008 1:25 AM


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Look for this in a future episode of CSI: Detectives expose a piece of paper, a shard of glass, or even a scrap of fabric to a chemical vapor, and within hours, dark brown fingerprints appear.Scientists in the UK report a new method of fingerprint detection that makes fingerprints on almost any material visible to the naked eye.But that’s not all:They say the same method can also read a sealed letter without opening the envelope.

Researcher Paul Kelly stumbled upon the discovery while studying the compound disulfur dinitride.His team first noticed the compound’s fingerprint imaging properties on laboratory glassware. When exposed to vapors of the compound, even in low concentrations, fingerprints left on the glassware would stain a dark brown.Residues from the fingerprints were causing disulfur dinitride to form a dark brown polymer.

The researchers ran with their new findings, imaging fingerprints on everything they could get their fingers on: Paper, pottery, aluminum foil, plastic wrap, glass, cotton, even a blank gun cartridge that had been fired.The surfaces don’t require any special preparation for the technique to work.

The researchers also found that residues from inkjet printing initiate the same reaction.The reaction is so sensitive that they could image a printed letter through a sealed envelope.They could even pick up text from an empty envelope that had once contained the letter. The researchers could make a pretty penny on this techniqueif only people still used snailmail.

Related Content: DISCOVER: Fingerprint Technique Shows What You've Eaten Discoblog: Want to Get Away With Murder? Use a Special Detergent Discoblog: Criminals, Beware: Your Name Might Be in Your DNA

Image: flickr / Beard Papa

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