Graphene Oxide Foam-Based Floating Actuators Manipulated via Dual-Marangoni-Effect Propulsion and Magnetic-Field-Guided Navigation.

Intelligent stimuli-responsive actuators that can convert environmental energies into mechanical works have garnered significant research interests. Among different actuation principles, Marangoni effect is distinguished due to simplicity, high efficiency, remote manipulation, and water environment adaptability. Nevertheless, both chemical and physical Marangoni actuators face their own challenges with respect to limited chemical loading, precise light illumination, and relatively poor motion controllability. In this study, floating actuators based on graphene oxide foam (GOF), manipulable via dual Marangoni effects and magnetic field, are fabricated by Direct Laser Writing (DLW). This is the first work to realize dual-Marangoni-effect actuators. Specifically, it is observed that the actuator driven by the chemical Marangoni effect can attain an average speed of 0.57 rad s^-1. Meanwhile, the actuator driven by the photothermal Marangoni effect is capable of reaching an average speed of 0.17 rad s^-1, and the average speed is 1.34 cm s^-1 under the manipulation of magnetic field. Multi-field coupling and dual Marangoni effects make actuators more flexible and intelligent, with promising potential for intelligent control and biomedical engineering.