Bio-Inspired Soft Magnetic Swimming Robot for Flexible Motions

Bio-inspired soft robots have gained significant attention for their flexible design and adaptability to various environments, making them suitable for exploration and task execution in confined or hazardous areas. However, the deformation and motion of soft magnetic robots rely on both their structural design and magnetization, which complicates the guided movement and balance maintenance for aquatic environments. In this work, inspired by the flat and symmetrical body of rays, we design a soft magnetic fish-shaped robot capable of flexible motions and trajectory swimming on the water surface. This robot features the muscle made of magnetic elastomer, which connects with the acrylic skeleton and silicone film fins with a soft body. In the external magnetic field, the robot achieves hovering by flapping its fins, driven by the magnetically actuated deformation of its magnetic muscle. Besides, the robot's axial magnetization enables the rapid steering guided by a horizontal field. In experiments, the soft magnetic robot was tasked with performing a looping figure-eight trajectory movement on the water surface, guided by the field gradient generated by a dense planar electromagnetic coils' array. When moving, the onboard circuit board of the robot collected its inertial and temperature information, and sent these data to the host computer via Bluetooth in real-time for motion monitoring. Received data demonstrated that our robot performed the specified afloat swimming trajectory, exhibiting a good stability on its yaw angle during the continuous motion. The soft magnetic swimming robot shows its integrated functionalities in untethered actuation, on-robot sensing, and wireless communication, indicating a significant prospect on applications in inspection and cleaning within narrow pipelines and enclosed mechanical interior spaces.