Roulette-Inspired Physical Unclonable Functions: Stochastic yet Deterministic Multi-Bit Patterning through the Solutal Marangoni Effect

Abstract

Physical unclonable functions (PUFs) have emerged as a hardware-based alternative to traditional cryptographic methods, which can be vulnerable to various types of threats, including physical tampering. PUFs exploit the unique and irreproducible variations in physical hardware to generate secure and distinctive identifiers, thereby offering a layer of security. However, the inherently random nature of PUF-generate data often sacrifices reliability and accuracy. To address this dilemma, this study introduces geometric multi-bit patterning based on dynamic wetting and dewetting phenomena. This method imbues PUF labels with both stochastic and deterministic properties. This novel strategy harnesses the high degree of randomness introduced by the solutal-Marangoni effect while achieving deterministic multinary quantized patterns through the polygonal confinement of binary-mixture liquid droplets, effectively resolving the reliability issues of traditional PUFs. The controlled dewetting mechanism is elucidated using micro-particle image velocimetry (µ-PIV), which pinpointed the precise moment of symmetry breaking within the internal flows of a binary solvent mixture. This approach allows for the facile creation of highly random PUF labels arranged in periodic pixel arrays, facilitating convenient, accurate, and fast authentication. Moreover, these labels are reconfigurable, transferable to various surfaces, and can be dyed with fluorescent molecules for versatile and robust, higher-level security applications.