Labels That Authenticate… Then Dissolve

Researchers at the Pohang University of Science and Technology (POSTECH) in South Korea have developed an eco-friendly smart security label that combines colour-based verification with holographic authentication. This sustainable alternative to conventional security labels can dissolve completely in water, leaving no trace.

The research team, led by Prof Junsuk Rho, designed the technology to address rising product counterfeiting and the increasing demand for biodegradable packaging materials. Traditional labels are often limited to basic holographic features or require expensive production processes, hindering widespread adoption.

To overcome these limitations, the team utilised metasurface technology, which involves ultrathin optical structures that use nanoscale patterns to manipulate light. They created a composite material by combining hydroxypropyl cellulose (HPC), a plant-derived compound used in food and cosmetics, with titanium dioxide nanoparticles measuring 4-6nm. When mixed, these nanoparticles embed densely within the cellulose, significantly enhancing its ability to control light.

The resulting metasurface produces vivid RGB colours in visible light while revealing a holographic image under UV light. This allows for a two-tier verification process where consumers can recognise colour indicators at a glance while inspectors verify hidden security information using specialised UV equipment.