Gradient assembled MXene/Fe3O4/CNF soft actuator with synergistic multilevel electromagnetic dissipation for interference shielding

Smart materials with multi-responsive soft actuators with desirable electromagnetic interference (EMI) shielding performance are greatly required for next-generation electronics. Herein, a mesoscale assembly strategy via layer-by-layer vacuum-assisted filtration is proposed to fabricate MXene/Fe 3 O 4 /CNF (MC) composite films with precise asymmetric concentration gradients. Driven by the significant hygroscopic swelling mismatch and superparamagnetism, the MC film exhibits high sensitivity and excellent actuation performance under humidity and external magnetic field stimuli. Programmable 2D-to-3D biomimetic “flower buds” and non-contact precise magnetic navigation are successfully achieved. Furthermore, leveraging the highly conductive surface of MXene, a smart switch is developed to convert environmental humidity fluctuations directly into logical electrical (ON/OFF) signals. The introduction of Fe 3 O 4 nanoparticles and the physical gradient structure effectively optimize the hysteresis loss of electromagnetic waves and the bottom-layer back-reflection-triggered multilevel energy dissipation, achieving an impressive EMI SE of 43.4 dB, governed by a reflection-dominated mechanism uniquely enhanced by internal absorption. Combined with rapid, wide-temperature-range photothermal conversion, this work provides a novel design paradigm for intelligent soft robotics and flexible passive electronics in complex environments.