Precision 3D printing of strongly magnetic soft structures containing high concentrations of NdFeB

•Development of a magnetic photosensitive resin with 35 wt.% NdFeB solid content•Silicone rubber coated release film reduces 3D printing release force by 60%•Magnetic particles in the resin degrade the mechanical properties of the structure•3D printed magnetic gripper can hold objects weighing up to 1.73 times itself The technological advancements in Digital Light Processing (DLP)-based 3D printing and magnetic photosensitive resins have provided a foundation for the fabrication of magnetic soft structures. Nonetheless, the fabrication of high-performance magnetic soft structures presents significant challenges, primarily stemming from the necessity to balance the concentration of magnetic particles within photopolymer resins and the resin's printability. Herein, we have developed a novel high-concentration NdFeB magnetic photosensitive resin, capable of achieving a magnetic particle concentration of up to 35 wt.%. Concurrently, we have refined the DLP printing technology, successfully enabling the continuous and stable printing of this high-concentration magnetic resin. We have printed complex structures with a maximum structural precision of 100μm and a magnetization strength of 21.5 emu·g-1. The printed structures exhibit an elongation at break of up to 105.3% and an average Young's modulus of 107.5kPa. Furthermore, we have printed a magnetic soft gripper that can grasp objects with a weight up to 1.73 times its own. This study Validates the viability and potential of DLP printing technology in the manufacturing of magnetic soft structures, which could inspire innovative designs and preparations for magnetic soft robots. [Display omitted]