Fighting Counterfeits With Nanopillars

The moisture from a breath of air reveals hidden patterns in a nanopillar-structured material.

AsianScientist (Aug. 13, 2014) – Nanopillar technology used in labels could be a new way to fight drug counterfeiting. The research demonstrating this finding has been published in the journal Advanced Materials.

Counterfeit drugs, which at best contain wrong doses and at worst are toxic, are thought to kill more than 700,000 people per year. While less than one percent of the US pharmaceuticals market is believed to be counterfeit, it is a huge problem in the developing world where as much as a third of the available medicine is fake.

To fight back against these and other forms of counterfeiting, a team of researchers including corresponding author Dr. Lee Seok Jae from the National Nanofab Center in South Korea have developed a way to make labels that change when you breathe on them, revealing a hidden image.

“One challenge in fighting counterfeiting is the need to stay ahead of the counterfeiters,” said Professor Nicholas Kotov, a co-author from the University of Michigan.

The method requires access to sophisticated equipment that can create very tiny features, roughly 500 times smaller than the width of a human hair. But once the template is made, labels can be printed in large rolls at a cost of roughly one dollar per square inch. That’s cheap enough for companies to use in protecting the reputation of their products—and potentially the safety of their consumers.

The labels work because an array of tiny pillars on the top of a surface effectively hides images written on the material beneath. Shyu compares the texture of the pillars to a submicroscopic toothbrush. The hidden images appear when the pillars trap moisture.

“You can verify that you have the real product with just a breath of air,” Kotov said.

Previously, it was impossible to make nanopillars through cheap molding processes because the pillars were made from materials that preferred adhering to the mold rather than whatever surface they were supposed to cover. To overcome this challenge, the team developed a special blend of polyurethane and an adhesive.

The liquid polymer filled the mold, but as it cured, the material shrunk slightly. This allowed the pillars to release easily. They are also strong enough to withstand rubbing, ensuring that the label would survive some wear, such as would occur during shipping. The usual material for making nanopillars is too brittle to survive handling well.

The team demonstrated the nanopillars could stick to plastics, fabric, paper and metal, and they anticipate that the arrays will also transfer easily to glass and leather.

The University of Michigan is currently pursuing patent protection for the intellectual property and is seeking commercialization partners to help bring the technology to market.

The article can be found at: Lee et al. (2014) Scalable Nanopillar Arrays with Layer-by-Layer Patterned Overt and Covert Images.

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Source: University of Michigan.
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