Spontaneous Formation of Random Wrinkles by Atomic Layer Infiltration for Anticounterfeiting.

Continuous developments of innovative anticounterfeiting strategies are vital to restrain the fast-growing counterfeit markets. Physical unclonable function (PUF)-based taggants allow for a practical solution to provide irreproducible codes for strong authentication. Herein, an advanced anticounterfeiting strategy with multiple security levels was successfully developed using screen printing and atomic layer infiltration (ALI) techniques. Macroscale poly(dimethylsiloxane) (PDMS) patterns were fabricated for primary verification. Spontaneous formation of random wrinkles with size in the micrometer scale was achieved on the top surface of screen-printed PDMS patterns due to the anisotropic relief and redistribution of extra compressive stress after Al2O3 infiltration, which can be used for senior authentication by image identification using the artificial intelligence (AI) technique. Furthermore, the complexity and security level of a code, which are proportional to the minutia density, can be adjusted by the morphology of the wrinkles in terms of amplitude and wavelength via the degree of Al2O3 permeation depending on ALI conditions. These spontaneously formed random wrinkles were demonstrated for validation and decoding with AI, exhibiting the merits of being unclonable, nondestructive, universally adaptable, environmentally stable, and mass-producible, and sufficiently adaptable for an industry-suitable authentication strategy.