Study on one-step 4D printing process via in-situ magnetization

Abstract The field of 4D printing technology is making rapid progress, with numerous complex smart materials being integrated into applications such as soft robotics, flexible electronics and biomedical devices. However, 4D printing based on magnetic control still faces challenges such as unstable materials and long printing process time. In this study, a one-step 4D printing device is developed to achieve in-situ magnetization and programming during the printing process without the need for material pre-processing. Meanwhile, the magnetization parameters and printing parameters were deeply co-optimized to solve the problem of sudden change in rheology when magnetization was performed during the printing process. On this basis, a magnetically controlled flexible actuator was developed to realize adaptive flexible clamping. The developed one-step 4D printing device simplifies the printing process while improving the printing speed and magnetic response. In-situ magnetization programming was successfully achieved through parameter optimization. The developed actuator can be folded by more than 60° in a magnetic field of 50 mT and the resulting structure has a remarkable actuation effect. The method was successfully applied to the fabrication of a crawling soft robot with a motion speed of 6 mm s ⁻¹ and a soft gripper capable of handling precision objects. This research provides new perspectives for soft robotics research and smart materials development, and offers a robust and efficient fabrication platform for functional magnetron devices.