Wood Robot with Magnetic Anisotropy for Programmable Locomotion

The development of environmentally-friendly stimuli-responsive materials is vital to green electronics, sensors, and biomedicine. However, fast responsiveness and precise locomotion control of biomass materials have not been accomplished. Herein, a magnetically responsive wood is reported that can achieve programmable locomotion in the rotating magnetic field. The magnetized wood is fabricated by removing lignin from the cell walls, which produces a porous microstructure, enabling facile and stable combination between NdFeB and wood. With the directional arrangement of magnetic moments after magnetization, the magnetized wood with obviously positive and negative magnetic poles is magnetic stability, and can complete various movements including spatial flipping, bypass obstacles, climb up, and down under the driven by magnetic torques. Meanwhile, the magnetized wood is lightweight (0.26 g cm −3 ), showing a fast walking speed of up to 11.3 mm s −1 under magnetic actuation (10 mT and 0.6 Hz), which is greater than those of petroleum-based polymeric materials. Benefitting from the unique porous structure, the magnetized wood can be used as the drug-carrier to deliver and release nano-cargoes effectively. This approach expands the range of stimuli-responsive materials beyond hydrogel, elastomers, and synthetic polymer, inspiring the creation of next-generation intelligent robots based on biocompatible and sustainable biomass materials.