Liquid crystal droplets used for PUF security

July 10, 2016 // By Peter Clarke
Researchers from the Universities of Luxembourg, Ljubljana and Vienna have developed a method to produce unique reflecting patterns that can be applied on valuable objects. As these patterns can’t be cloned or copied, they could be used to identify products unambiguously in order to avoid counterfeiting.

The researchers have used properties and interaction of cholesteric liquid crystal material in microspheres to produce these unique patterns of reflection.

Thanks to the self-assembled periodic structure that is characteristic of this type of liquid crystal, the spheres reflect specific colors as a result of interference and in the same manner as butterfly wings and peacock feathers.

Microfluidic MEMS makes it possible to prepare large quantities of monodisperse droplets or shells of cholesteric LCs It has been observed that in assemblies of such droplets photonic cross communication develops giving rise to multi-coloured patterns that are tunable. A collection of such cholesteric liquid crystal spheres therefore can have a unique optical characteristic that is practically impossible to copy and any attempt at tampering with any given arrangement is likely ruin the structure.

Related links and articles:

www.uni.lu

High-fidelity spherical cholesteric liquid crystal Bragg reflectors generating unclonable patterns for secure authentication

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