Degradable Magnetic Composites from Recycled NdFeB Magnets for Soft Actuation and Sensing

Abstract

As soft robotic and flexible magnetic sensing technologies transition from laboratory prototypes to real‐world applications such as biomedical and inspection robots and wearable sensors, ensuring their environmental sustainability becomes increasingly important. Conventional magnetic composites—typically made from nondegradable polymers and rare‐earth fillers—pose substantial ecological challenges due to limited recyclability and forecasted high material consumption due to an increase in robotic and wearable technologies. In this work, fully degradable, recyclable magnetic composite is reported that integrates mechanical compliance, rapid magnetic responsiveness, and multifunctionality. The composite consists of recycled neodymiumironboron (NdFeB) microparticles (particle sizes 2–55 μm), recovered from end‐of‐life industrial rotor pumps, embedded in a biocompatible gelatin–glycerol/1,3‐propanediol organogel matrix designed for rapid degradation, recycling, and reshapeability. By tuning the magnetic filler content (10 to 70 wt%), the composite achieves a broad mechanical range (ultimate strength: 100–500 kPa; elongation up to 750%), while enabling high‐speed soft robotic locomotion (0.5–5 robot body lengths per second) and magnetoelastic sensitivity under dynamic loads. Benefiting the reversible hydrogen bonding network and triple‐helix entanglement in the gelatin organogel, the magnetic composite shows the designed recyclability. Two closed‐loop recycling methods—green solvent‐assisted organogel degradation (completed within 1 min at 80°C) and temperature‐controlled reshaping—enable rapid recovery and reuse of the magnetic filler and matrix, respectively. Experimental demonstrations include magnetically actuated crawlers and worm‐like robots that can be disassembled, degraded, and remolded into new forms on‐demand. Additionally, magnetic sensors have been developed for applications such as interactive or assistive devices, enabling detection of touch intensity, heel‐strike, balance, and contactless proximity. This work presents a pathway toward sustainable magnetic composite for soft robotics by using recycled magnetic powder, and enabling design for recycling, repurposing, and multifunctionality directly at the material level.