Reprogrammable shape transformation of magnetic soft robots enabled by magnetothermal effect

Magnetic soft robots are promising for diverse applications, since they can achieve multimodal locomotion through programming magnetization. However, reprogrammable magnetization of soft robots remains a challenge. Here, we prepare a magnetic elastomer containing both Fe3O4 and CrO2 particles, where Fe3O4 nanoparticles can be heated through the magnetothermal effect. Once the temperature exceeds the Curie point of CrO2 particles, the original magnetization profiles of the elastomer can be erased and re-written. We tune the magnetization profile of a one-dimensional magnetic strip to realize three shape transformation modes, and the reprogrammed magnetization profiles are validated experimentally. The magnetothermal heating process is simulated. We also demonstrate reprogrammable shape transformation of two-dimensional magnetic soft structures. Finally, a reprogrammable hand-shaped soft robot is designed and used as a magnetic switch in a LED circuit.