Cephalopod‐Inspired Chemical‐Gated Hydrogel Actuation Systems for Information 3D‐Encoding Display

Abstract Cephalopods evolve the acetylcholine‐gated actuation control function of their skin muscles, which enables their dynamic/static multimode display capacities for achieving perfectly spatial control over the colors/patterns on every inch of skin. Reproduction of artificial analogs that exhibit similar multimodal display is essential to reach advanced information three‐dimensional (3D) encoding with higher security than the classic 2D‐encoding strategy, but remains underdeveloped. The core difficulty is how to replicate such chemical‐gated actuation control function into artificial soft actuating systems. Herein, this work proposes to develop azobenzene‐functionalized poly(acrylamide) (PAAm) hydrogel systems, whose upper critical solution temperature (UCST) type actuation responsiveness can be intelligently programmed or even gated by the addition of hydrophilic α‐cyclodextrin (α‐CD) molecules for reversible association with pendant azobenzene moieties via supramolecular host–guest interactions. By employing such α‐CD‐gated hydrogel actuator as an analogue of cephalopods’ skin muscle, biomimetic mechanically modulated multicolor fluorescent display systems are designed, which demonstrate a conceptually new α‐CD‐gated “thermal stimulation‐hydrogel actuation‐fluorescence output” display mechanism. Consequently, high‐security 3D‐encoding information carriers with an unprecedented combination of single‐input multiple‐output, dynamic/static dual‐mode and spatially controlled display capacities are achieved. This bioinspired strategy brings functional‐integrated features for artificial display systems and opens previously unidentified avenues for information security.