Design and characterization of a programmable self regulation hybrid material system: wrinkled hydrogels and plasmonic nanoparticl lattices

In this research, a self-regulating system of wrinkle-patterned hydrogel with tunable feedback cycle timescales will be presented where wrinkled pattern senses humidity variation and plasmonic nanoparticle (PNP) lattice regulates through the plasmonic heating.  In the feedback loop, moisture absorption makes the hydrogel’s wrinkled surface to flatten thus, less light scattered and more transmitted through the flattened surface of the system to the plasmonic PNP lattice at the bottom layer. Due to light absorption, PNP lattice generates heating that makes the hydrogel dries out and ultimately leading to the formation of wrinkles at the surface. Thus, less light transmitted and more scattered from the wrinkled surface of the system. Therefore, cooling and moisture absorption flatten wrinkle patterns thus initial configuration is restored. Time-dependent finite element analysis reveals thermal and mechanical mechanisms of wrinkle formation. Simulations were consistent with the experiments in terms of wrinkle characteristics, timescale and temperature range. Thermomechanical modeling could aid engineering the time-scale of regulatory systems by tuning the system parameters for the design of future responsive materials and smart systems.