New ‘fingerprints’ go down to the wire

Forgers look set to have their jobs made

harder as scientists are developing tiny wires to be used to produce “nanoscale fingerprints” that are invisible to the human eye.

They may offer a way to authenticate goods, prove ownership of a credit card or provide bank notes that cannot be counterfeited.

The “fingerprints” are actually a sprinkling of silver nano-wires stuck on to a thin plastic film. They are millionths of a metre thick and 20 to 30 of them are scattered on to the film randomly to produce a unique pattern, said Prof Hyotcherl Ihee from the Korea Advanced Institute of Science and Technology and Institute for Basic Science.

To make it even more difficult for counterfeiters Prof Ihee's research group coloured the wires with fluorescent dyes so the fingerprints have unique physical patterns and dye combinations. They describe their work this morning in the Institute of Physics (IOP) publishing journal Nanotechnology .

It would be difficult for the typical counterfeiter to crack such a code, Prof Ihee said. "It is nearly impossible to replicate the fingerprints due to the difficulty in trying to manipulate the tiny nano-wires into a desired pattern." The use of dyes adds to the complexity.

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He says tags made using this technology could be used to authenticate electronics, drugs, credit cards and even bank notes. They could be produced for 72 euro cent each because of the rapid process used to make the tags.

The fingerprints would be invisible to the naked eye, but could be read by specialised microscopes using a system that could be automated.

The research team suggested a different approach where the fingerprint could be tagged with a unique ID or barcode of its own to speed up the process of confirming an item as genuine. The barcode would be scanned and then the fingerprint on the presented tag could be compared against the one held on file.

“Once a pattern is tagged and stored on a database using a unique ID, a certain substrate, whether this is a bank note or a credit card, could be authenticated almost immediately by observing the fluorescence images and comparing it with stored images,” said Prof Ihee.