<i>In Situ</i>   Reprogrammable Magnetic Microrobots

Programmability is essential for magnetic microrobots to achieve adaptive and multifunctional behaviors. However, most existing systems lack reconfigurability after deployment. Here, we present a reprogrammable microrobot platform based on nickel nanowires of distinct diameters embedded in SU-8, leveraging the difference in their coercivities to enable in situ magnetization switching. A fast, purely magnetic reprogramming strategy is developed, allowing the selective reversal of magnetization states without thermal or structural changes. We systematically explore the effects of ramp time, magnetic field strength, and microrobot geometry on reprogramming success and demonstrate six distinct deformation and locomotion modes in a multisegment robot. The scalable UV photolithography-based fabrication process ensures a high yield and design flexibility. This work provides a generalizable and efficient approach toward reprogrammable microrobotic systems with potential for future applications in dynamic environments such as biomedical actuation or soft robotic manipulation.