Bio-Inspired Photonic Crystal Actuator

In nature, many organisms exhibit remarkable abilities to simultaneously alter their body shapes and surface colors in response to external stimuli. Inspired by these natural phenomena, significant research efforts have focused on developing color-tunable soft actuators with applications in soft robotics, artificial muscles, mechanical motors, and energy conversion devices. This review distinctively highlights recent advancements in integrating photonic crystal structures into actuating materials, emphasizing three novel contributions compared to existing literature: comprehensive analysis of fabrication strategies, diverse stimulus-response mechanisms, and the design of innovative biomimetic devices. The uniqueness of this study lies in its detailed exploration of photonic crystal actuators fabricated from polymers, hydrogels, and cholesteric liquid crystals, responding to stimuli such as photo, temperature, humidity, magnetism, and biological factors, including myocardial cells. Furthermore, it critically discusses practical applications across various fields, including displays, mechanical manipulation devices, soft crawling and swimming robots, energy converters, and visual sensing technologies. Finally, this review proposes forward-looking research directions, underscoring the potential for photonic crystal actuators to significantly advance intelligent material systems and practical biomimetic applications.