Tiny edible tag could help fight counterfeit drugs

Created by researchers at Purdue University, the tag uses a technique called ‘physical unclonable functions,’ or PUF, that was originally developed for authentication in information and hardware security. The tag acts as a digital fingerprint, generating a different response each time it is scanned under a compatible LED light. According to the Purdue team, this makes them extremely difficult to duplicate, even for the original manufacturer. The work appears in Nature Communications.  

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"Every single tag is unique, offering a much higher level of security," said Young Kim, an associate professor in Purdue's Weldon School of Biomedical Engineering.

While PUFs have been around for some time, the researchers claim this is the first time an edible version has been made. It’s constructed of a thin, transparent film made from silk proteins and fluorescent proteins genetically fused together. Shining various LED light sources on the tag excites the fluorescent silk microparticles, causing them to generate a different random pattern each time.

Those microparticles emit cyan, green, yellow or red fluorescent colours. Digital bits can then be extracted from an image of those patterns to produce a security key, which a pharmacy or patient can then use to confirm the drug’s authenticity.

Counterfeit drugs make up at least 10 per cent of global pharmaceutical trade, according to the team, costing thousands of lives each year. By combining the tags with a compatible smartphone app, the team believes the technology could play an important role in the battle against fake medicines.

"Our concept is to use a smartphone to shine an LED light on the tag and take a picture of it,” said Jung Woo Leem, a biomedical engineering postdoctoral associate at Purdue. “The app then identifies if the medicine is genuine or fake."

It’s been established that the tag works for at least a two-month period without the proteins degrading. The next steps will see the researchers aiming to confirm that the tag can last as long as a drug does and that it doesn't affect a medicine's key ingredients or potency.