Development of a Photo-Curing 3D Printer for Fabrication of Small-Scale Soft Robots With Programming Spatial Magnetization

The magnetic soft robot has potential applications in biomimetic, soft interaction, and biomedical fields. However, its functionality depends on deformation patterns and locomotion modes, challenging the fabrication of complex structures with precise magnetization. Therefore, we developed a programming magnetization photo-curing 3D printer for fabrication of small-scale soft robots. The printer integrates a three-dimensional magnetic field generator (3D-MFG) and a digital light processing photo-curing system. The 3D-MFG generates a high-strength (up to 80 mT) magnetic field through Halbach arrays (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x-y</i> plane) and a solenoid (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z</i>-axis), generating arbitrary uniform magnetic field with low energy consumption. Adhesion between the printed structure and the substrate was analyzed, and A real-time force-based printing control method is presented for precise optimization of key parameters, including layer thickness, approaching force, and separation speed, enhancing overall print quality and reliability in stacking of complex three-dimensional structures. Finally, a crawling robot mimicking inchworm gait, a swimming robot with butterfly-inspired motion, and a capsule robot for targeted drug delivery were fabricated by the developed system. These experimental results validated the printer's capability to fabricate highly complex structures, advancing the practical application of small-scale soft robots in biomimetic and biomedical fields.