A Biomimetic Soft Actuator Achieves Efficient Fluorescence via Covalent Cross‐Linking

Abstract The bioluminescence mechanisms of deep‐sea organisms provide innovative ideas for biomimetic design. To meet the detection needs in low‐light deep‐sea environments, the development of soft robots with high‐brightness luminescence is crucial for long‐term in situ observation. Directly incorporating high‐performance fluorescent molecules into hydrogel matrices presents challenges: fluorescent molecules tend to dissociate in physically crosslinked systems, and complex aqueous environments may lead to instability in the material structure. These issues limit the fluorescence stability and service life of underwater devices. Inspired by the behaviors of marine organisms, this study proposes a biomimetic soft actuator with high fluorescence intensity. The actuator adopts a bilayer hydrogel structure, where the luminescent layer (PT4B‐N), covalently crosslinked with fluorescent molecules, achieves a high photoluminescence quantum yield (PLQY > 60%), and the pH‐responsive driving layer (PNPC) enables motion control (strip‐shaped hydrogel: maximum bending angle ≈360°, cycle time ≈20 min). The experimental results demonstrate that the actuator can realize biological‐like synergic fluorescence and shape change (SFSC) behavior.