Cholesteric Liquid Crystals Based Micro‐Fingerprints Generator for Anti‐Counterfeiting Labels

In this study, a method is presented to fabricate optical fingerprint-like patterns. The method relies on the use of commercially available chiral nematic liquid crystals (CNLCs) confined in microspheres. The peculiar optical texture is obtained by applying a high-frequency voltage to the micrometric objects able to distort the molecular director orientation. The texture can be stabilized by doping the CNLC with photosensitive materials. Each microsphere shows a different fingerprint-like pattern that is generated in a completely random manner making this procedure suitable to create physical unclonable functions (PUFs) keys. The optical patterns can be stored to create an artificial fingerprints database or they can be used to fabricate electroluminescent labels to be exploited as complex anti-counterfeiting devices. An authentication software is developed and used to test the robustness of the proposed anti-counterfeiting system.