Automated Assembly of Magnetic Soft Microrobots With Chopstick-Like Two-Fingered Microhand

The development of magnetic soft microrobots has been constrained by the lack of precise control of microactuator's programmability. To address such an issue, we use a piezo-driven two-fingered microhand to selectively position the magnetic microactuators within a soft scaffold. Each microactuator is sequentially oriented to a desired direction through surface rotation by applying magnetic field-based torques, and is then fixed to the scaffold using ultraviolet (UV) cross-linking. A detailed analysis is conducted on the spatial positioning capability of the microhand's parallel mechanism and the magnetic programming performance of electromagnetic coils' orientation control. To overcome the inefficiency and inaccuracy of labor-intensive manual assembly, we propose an automated assembly strategy to create magnetic soft-bodied microrobots following our design. The multiple fabricated microrobot prototypes exhibit programmed 2D and 3D shape transformations and various robotic gaits for surface locomotion. This strategy can enable the rapid fabrication of multimaterial 3D magnetic microrobot designs with potential applications in robotics, biomedical engineering, and environmental governance. Note to Practitioners - The motivation of this work is to address the limitations in current fabrication methods for magnetic soft microrobots, which include 3D printing, heating, mold casting, and chemical synthesis. These approaches fall short when creating microrobots with arbitrary structures, multimaterial compositions, and complex magnetization profiles. Micro-assembly offers a potential solution, yet existing techniques depend on either time-consuming manual assembly or costly equipment lacking sufficient flexibility for 3D spatial manipulations. In this work, a 3-degree-of-freedom, high-precision parallel microhand-based assembly method is proposed. The microhand provides high precision and speed for rapid positioning of assembly modules, while electromagnetic coils enable precise orientation in magnetization programming. Experimental results confirm the effectiveness of this method and demonstrate the robustness and adaptability of the automated fabrication strategy. This approach facilitates the fabrication of magnetic soft microrobots with specific deformation and locomotion capabilities according to design intent.