POS4-0179
Dual-Responsive Hydrogel Interferometric Patches for Multi-Factor Optical Encryption
Topic
S4. Colloids, Interfaces, and Molecular Assemblies for Functional Soft Materials
When and Where
Sep 29, 2026
08:30 - 09:30
Room 301 (Grand Ballroom)
Session Chairs
Hae Jung SON
Boseok KANG
Presenter(s)
Hyein Jin (POSTECH)
Co-Author(s)
Abstract
Tunable structural color-based optical encryption systems have attracted significant attention for their ability to dynamically modulate optical signals in response to external stimuli. However, most existing systems rely on a single stimulus, leaving encoded information vulnerable to decryption once the triggering condition is known. Here, we report dual-responsive hydrogel interferometric patches that achieve multi-factor optical encryption through the combined effects of humidity and pH. The platform utilizes hydrogel thin films functionalized with phenyl azido groups, which enable UV-induced photo-crosslinking to transform the azido derivatives into a water-insoluble hydrogel network. Structural colors are generated through thin-film interference, while environmental stimuli modulate the optical response by altering the hydrogel thickness. Upon exposure to humidity, the optical response is primarily governed by the phenyl azido group grafting ratio, where hydrogels with different grafting levels exhibit distinct water uptake capacities and swelling characteristics. In contrast, under pH stimuli, the swelling ratio is influenced not only by the grafting ratio but also by the ionization state of the polymer network. The ionization-dependent electrostatic repulsion further modulates hydrogel expansion, providing an additional factor for controlling the optical response. Furthermore, the device is fabricated on a flexible substrate, enabling its use as a wearable optical security patch. The proposed platform demonstrates strong potential for advanced anti-counterfeiting technologies, secure information storage, and wearable authentication systems.
