Sesame seed-sized, anti-counterfeit tag gets smart glue upgrade

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RFID tags and other product identifiers such as barcode labels are useful in keeping track of goods across supply chains, but they have their limitations. You can put an RFID tag or barcode label on the outside of a product or box of supplies, but what about the smaller items inside? Paving the way for many more components to be securely labeled is an anti-counterfeit tag that measures just 2 x 2 mm (about the size of a sesame seed) devised by researchers in the US.

The approach, which was first unveiled in 2020, uses terahertz radiation to read cryptographic codes stored on the tiny chips. Similar to RFID designs, the data transfer process can be powered by energy emitted from the scanner, which means that the anti-counterfeit tag needs no battery and should last for years.

What is terahertz radiation?

Terahertz radiation has been described as light that is almost heat. And the terahertz range of frequencies sits at the far end of the infrared band, adjacent to the microwave band, within the electromagnetic spectrum.

Not only can these submillimetre waves pass through clothing and plastics to image hidden objects, terahertz radiation can also be used to identify materials in its path based on spectroscopic fingerprints.

Given these properties, it’s no surprise to learn that the terahertz portion of the electromagnetic spectrum is ripe with security scanning applications. What’s more, unlike X-rays, terahertz radiation is non-ionizing – meaning that it won’t damage living cells.

So far, so good, but – as observers have highlighted – the original design of the MIT group’s anti-counterfeit tag shared a security vulnerability common to mainstream technology such as conventional RFID labels. By simply removing the security ID from a genuine product and attaching it to a fake item, counterfeiters would be able to easily defeat the authentication system.

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To combat this, the team has come up with an ingenious solution, which centers on the glue used to attach the anti-counterfeit tag to the host product. Small metallic particles are added to the adhesive during formulation and their final pattern when the tag is deployed is used as a security property.

“These metal particles are essentially like mirrors for terahertz waves. If I spread a bunch of mirror pieces onto a surface and then shine light on that, depending on the orientation, size, and location of those mirrors, I would get a different reflected pattern. But if you peel the chip off and reattach it, you destroy that pattern,” explains Ruonan Han – leader of the Terahertz Integrated Electronics Group.

The team is presenting its latest design at the 2024 IEEE International Solid-State Circuits Conference (ISSCC), which is taking place this week in San Francisco, CA. To incorporate the new security feature, users would take a reading of the anti-counterfeit tag when it was first attached to an item and then use that pattern data for verification.

Collaborating with colleagues at the MIT Computer Science and Artificial Intelligence Laboratory (CSAIL), the researchers have shown how a machine learning model can be trained to match glue patterns with more than 99 percent accuracy.

The MIT project is by no means the only effort to secure supply chains. Quantum Base – a spin-out from Lancaster University in the UK – uses nanoscale quantum physical unclonable functions to assert that labeled goods are authentic. The anti-counterfeit solution is said to be impossible to copy, clone or fake and authenticates in seconds using a regular smartphone.

As Quantum Base points out, there are multiple reasons why firms would want to invest in anti-counterfeit tag technology. Companies that are unable to validate critical elements of their supply chain put their reputation at risk and expose themselves to substandard products.

The firm’s solution is based on carbon nanomaterials that – when applied to surfaces – can be used to generate security fingerprints, which are reported to be more unique than DNA.