Humidity-Compensated Multi-Stimuli Soft Actuator with Asymmetric Bilayer Design.

Biological systems execute complex motions by concurrently processing light, moisture, and magnetic stimuli, inspiring the development of multistimulus actuators. However, traditional rigid actuators face inherent limitations in size, structural complexity, and application versatility, restricting their use in extreme or multifunctional scenarios. Herein, we develop a multistimulus-coupled soft actuator by vacuum-filtering graphene oxide (GO) and spraying a composite of graphene, polydimethylsiloxane (PDMS), and Fe3O4. The asymmetric bilayer design enables programmable deformation under light, humidity, and magnetic fields, replicating biomimetic motions such as jellyfish swimming, pine-cone closing, and earthworm crawling through tunable stimulus parameters. Notably, a humidity-induced residual deformation compensation mechanism enables near-complete recovery (98.5%) from photothermal bending, overcoming a key limitation in existing multistimulus actuators. This work establishes a humidity-compensated, multistimulus paradigm that bridges nanophotonics, elastomer mechanics, and hydration dynamics for intelligent soft robots.