Glowing chemical lights up a suspect's fingerprints

Nicola Guttridge, contributor

(Image: Rex Features )

A door knocked off its hinges. Furniture in disarray. A billowing curtain, masking an open window. A crime scene - complete with murder victim. But whodunnit?

Dusting for prints may seem like the obvious next step, but a new method may literally shed light on the culprit. Research led by Bin Su at Zhejiang University in Hangzhou, China, uses a type of luminous glow known as electrochemiluminesence (ECL) to make fingerprints show up.

Prints are currently detected using a physical or chemical "developer", for example powder dusting or chemical fuming. These methods rely on the fingerprint absorbing and reacting with this developer, destroying or altering the print itself. Non-destructive methods are better, but more expensive. Su and colleagues suggest a method for identifying prints that is non-destructive and could potentially be used on fingerprints whether they are fresh or old, complete or smudged.

Rather than highlighting the print itself, this method instead lights up the background surface, producing a negative image of the fingerprint. This clearly shows not only the ridge pattern, but also fine details like the branching and ends of lines, as well as the distribution of sweat pores, says Su. The technique could also be used to hunt for evidence of illegal drug use.

ECL is produced in solutions during chemical reactions, or can be generated in a lab. By applying a voltage to a conducting material such as steel, electrons become excited. They form compounds in this excited state and then lose energy, emitting light - ECL - as they drop back down to their original state.

Su's method is limited by the need for prints to be on a conducting material. However, the researchers are working on methods to collect and transfer prints from any surface using ECL.

Journal reference: Angewandte Chemie, DOI: 10.1002/anie.201203815

Source: http://feeds.newscientist.com/c/749/f/10897/s/2238d0fc/l/0L0Snewscientist0N0Cblogs0Conepercent0C20A120C0A80Cfingerprints0Eecl0Bhtml0DDCMP0FOTC0Erss0Gnsref0Fonline0Enews/story01.htm

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