Preparation and Motion Study of a Light and Magnetically Driven Micro Soft Robot Mimicking the Cownose Ray

In narrow, unstructured environments such as environmental monitoring and minimally invasive medical procedures, micro soft robots exhibit unique advantages due to their flexible movement capabilities and small size. Existing micro soft robots often employ single physical field control, making it difficult to achieve multi-dimensional complex movement behaviors. This study, based on the bio-mimicry of the swimming principle of the cownose ray, designed and prepared a cownose ray-inspired micro soft robot with dual light and magnetic responsiveness. Firstly, a photosensitive hydrogel was prepared using a certain proportion of hollow glass microspheres (HGMP), polydopamine (PDA), poly(N-isopropylacrylamide) (PNIPAM), and agarose. Under 808 nm near-infrared light irradiation, the hydrogel achieves a maximum upward floating speed of 23.31 mm/s in water. Then, a magneto-elastic composite film was prepared using a certain proportion of neodymium-iron-boron (NdFeB) and polydimethylsiloxane (PDMS), which will undergo controllable bending deformation under the action of a magnetic field. Finally, by integrating the photosensitive hydrogel and the magneto-elastic film, a cownose ray-inspired micro soft robot with both light and magnetic responsiveness was prepared. By controlling the on-off state of near-infrared light, the robot can achieve multi-modal behaviors such as floating, moving, diving, and hovering. Simultaneously, it can perform straight swimming under magnetic field drive. This study enriches the driving modes of micro soft robots and provides a reference method for the multi-physical-field driving of robots in complex environments.