Moisture-Sensitive\nFe<sub>2</sub>O<sub>3</sub> Nanoparticle-Based\nMagnetic Soft Actuators

Multifunctional soft robots are emerging as a new-generation\nintelligent\ndevice for challenging environments. To meet the requirements of smart\napplications and soft robotics, developing a soft actuator capable\nof multiple functions and mechanical deformation is essential. In\nthis study, we designed a free-standing magnetic soft actuator constructed\nfrom iron oxide (Fe<sub>2</sub>O<sub>3</sub>) nanoparticles and poly(vinyl\nalcohol) (PVA), that responds to both moisture and magnetic fields.\nWe used computational modeling (density functional theory and ab initio\nmolecular dynamics) to explain the experimental findings demonstrating\nthe deformation and high-bending angle (∼150°), which\nis about twice as large under combined moisture and magnetic field\nexposure compared to their individual effect. Additionally, a flower-shaped\nsoft robot was designed by using the continuous bending deformation\nof the actuator in response to moisture changes, performing directional\nbending in an ambient environment. These findings demonstrate the\nmaterial’s sensitivity to moisture and magnetic fields, opening\nup new possibilities for designing responsive structures in the smart\ndevice industry.