Dynamic Interactions of Micro- and Nanoparticles for Generating Random Patterns in Physically Unclonable Functions

Micro- and nanoparticle assemblies formed by coating processes offer a practical route to generating random patterns for physically unclonable functions (PUFs). To enable advanced security systems that protect personal information from counterfeiting and hacker-enabled theft, PUFs must provide not only high uniqueness, randomness and stability, but also excellent scalability. In particle-based PUFs produced by stochastic assembly, complex interparticle interactions act as key sources of entropy, and are strongly governed by the coating process. Accordingly, the development of optical and electrical PUFs for purpose-specific hardware security requires careful selection of coating methods and precise control of particle dynamics during processing to yield random patterns tailored to the target application. In addition, compact readout platforms are needed to ensure broad user accessibility while safeguarding privacy. This review surveys optical and electrical PUFs based on solution-processed particle assemblies, covering particle materials, the parameters that regulate interparticle interactions, and coating methods for particle assembly, as well as emerging applications. Finally, we discuss outstanding challenges and outline future research directions toward practical, robust cryptographic systems for next-generation security technologies.