Fin-Wave-Inspired Wireless Small-Scale Soft Robot for Adaptive Amphibious Locomotion Under Single-Mode Magnetic Field

Magnetic soft robots are capable of generating programmable deformation based on variable magnetization profiles, with the added potential advantages of easy fabrication and miniaturization. However, achieving efficient locomotion and maneuverability in complex and variable environments often requires intricate modulation of external magnetic field which limits their applications. Inspired by the undulating fin-wave often seen in aquatic organisms, this paper demonstrates a small-scale soft robot capable of adaptive amphibious locomotion under a rotating magnetic field, allowing the robot to efficiently move on the solid surface (dry) and in liquids (wet). The robot comprises of a combination of multiple soft rod-shaped legs (6 × 1 ×1 mm) with different magnetization directions capable of generating undulating waves. Simulation of the undulating wave is conducted based on Cosserat rod theory to aid in the design and arrangement of the legs. The maneuverability and capability of steering and transitioning from dry to wet surfaces as well as sinking and floating in hybrid environments are demonstrated. The robot's ability to move with and against the flow of liquid in pipes of variable diameter is studied and characterized. The results demonstrate the potential to use as a small-sized wireless robot in applications, such as navigating within human blood vessels for clinical interventions.