It seems that the more technology progresses, the easier it becomes to produce convincing counterfeit goods. Scientists at the University of Copenhagen are fighting back, however, with product tags that they claim cannot be replicated – even by an item's legitimate manufacturer.

Known as the physical unclonable functions (PUFs) system, the technology was developed by researchers Riikka Arppe-Tabbara, Mohammad Tabbara and Thomas Just Sørensen.

They created 9,720 of the tags by laser-printing QR codes onto regular paper, then spraying a translucent microparticle-containing ink over top of each one. While the codes were still readable, the particles also showed up as patterns of tiny white spots on a black background (when magnified). Because of the random scattering nature of the spraying method, those patterns were unique to each tag.

The scientists next photographed every one of the tags with a smartphone camera, in order to create a digital registry in which each microparticle pattern was linked to its corresponding tag.

When the tags were subsequently photographed by different smartphones, and the images of their particle patterns were compared to those in the registry, it was possible to tell which pattern belonged to which tag with an accuracy rate of 76 percent – in some cases another photo had to be taken with the "reading" phone, as the original was out of focus, or the tag was dirty. In no cases did the system incorrectly match a pattern to a tag.

It is hoped that once the technology is refined, the tags could be manufactured utilizing commercial printing and coating processes. They could subsequently be affixed to items such as luxury goods or medications before shipping, then used by stores or customers to authenticate that those items are the genuine article.

A paper on the research was recently published in the journal ACS Applied Materials and Interfaces.

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