3D printing of magnetically actuated miniature soft robots

Magnetically actuated soft robots possess great potential for applications in medical surgery, bioengineering, and micromanipulation due to its fast response, easiness to manipulate, and untethered control. However, it remains a challenge to fabricate flexible magnetically actuated soft robots by magnetic materials with a high viscosity (≥10⁴ Pa.s). Therefore, we proposed a microscale Weissenberg effect-based 3D printing technique for fabrication of magnetically actuated soft robots via the programmable magnetization of high-viscosity magnetic polymer precursor prepared by mixing magnetic microparticles with elastic polymer. The magnetic microparticles in precursor solution can be reoriented by applying a magnetic field around nozzle during direct writing, which imparts the programmable sequences of magnetic polarities to printed structures. Meanwhile, we investigated the effect of main process parameters on the morphologies of printed structures. 3D shape transformations of a 2D patterned structure and the grasping experiment of a magnetically actuated cross shaped soft gripper verified the effectiveness of the programmable magnetization of high-viscosity flexible magnetic materials for the proposed 3D printing technique.