Designing Physical Unclonable Functions From Optically Active Materials

Physical unclonable functions (PUFs) are artificial "fingerprints" provided by physical devices to authenticate manufactured goods. Their inherent unclonable nature positions them as one of the most promising tools to tackle global counterfeiting challenges. Leveraging the large parameter space in solution chemistry, chemically generated PUFs can achieve excellent device performance. Particularly, optically active materials have become valuable security inks thanks to their versatile, non-invasive, and non-destructive readouts, and PUF devices generated from stochastic nano-/micro-patterns of optical inks hold great potential. This review highlights recent advances in the design of optical PUF devices. A range of resonant and non-resonant optical materials used as security taggants are presented and their incorporation in state-of-the-art PUF devices is examined using non-deterministic fabrication techniques. By outlining design criteria, challenges, and opportunities, a roadmap is provided for developing next-generation PUFs using established and emerging optical probes and help advance security and reliability in anticounterfeiting technologies.