Bioinspired light-driven photonic crystal actuator with MXene-hydrogel muscle

The butterfly Apatura ilia's wings change colors during flapping, which plays a major role in conveying information and avoiding predators. Inspired by the muscle-driven flapping mechanism, here, we fabricate a highly efficient photothermally responsive MXene-hydrogel muscle and achieve a dynamic structural color imaging system based on the MXene-hydrogel muscle manipulated photonic crystal actuator arrays. Our optimized MXene-hydrogel-muscle artificial muscle has a stable and quick photothermal response owing to the high photothermal transformation efficiency of MXene (∼100%). Consequently, our photonic crystal (PhC) actuator exhibits robust structural stability and fatigue resistance (more than 500 cycles), and its response time is ∼5 s. The PhC actuator can give real-time visual feedback in response to heating and near-infrared irradiation. They offer exciting possibilities for applications in sensors, displays, camouflage coatings, cryptography, and many other fields. Our experiments and theoretical analysis reveal the quantitative structure-activity relationship of the responsive PhC actuator.