A watermark made of nanoscopic polyurethane pillars that remains invisible until it is breathed on has been developed by U.S. students.
A University of Michigan team, along with research partners in South Korea, say the process creates a label that cannot be easily copied. It is now looking to commercialize and protect the innovation.
Chemical engineering professor Nicholas Kotov said the challenge in fighting fake consumer goods is “the need to stay ahead of the counterfeiters.”
An array of tiny pillars on the top of a surface — comparable to a sub-microscopic toothbrush, say the team — hides the image beneath.
When moisture from a breath gets between the minute polyurethane pillars, the image is revealed.
Equipment capable of creating features 500 times smaller than the width of a human hair is required — an expense researchers believe will render it beyond counterfeiters' reach. However, they also claim the labels can be manufactured at $1/inch 2 once the template is made.
The nanopillars — made from a blend of polyurethane and adhesive — bond with plastics, fabric, paper and metal say developers, who are also confident it will work effectively on glass and leather.
A paper, Shear-Resistant Scalable Nanopillar Arrays with LBL-Patterned Overt and Covert Images, was published on the journal Advanced Materials website in August.