Femtosecond Laser‐Regulated Microstructures for on‐Demand Functionalization of Magnetic Milli‐Robots

Recent advancements in smart materials and robotics have propelled the development of magnetic milli‐robots with significant potential in biomedical diagnostics, industrial automation, and environmental monitoring. However, the challenge of achieving in situ functionalization of these small, flexible robots without compromising their magnetic agility has hindered their widespread deployment. Herein, a femtosecond laser‐driven hierarchical assembly mechanism that facilitates the seamless integration of Additive‐LIPSS (laser‐induced periodic surface microstructures) combined with plasmonic nanoparticle deposition through a single step is proposed. This approach effectively overcomes the traditional trade‐off between multifunctionality and miniaturization, offering a pathway for precise and scalable functionalization of magnetic milli‐robots. By exploiting the strain‐tunable property of the soft magnetic substrate, we achieve programmable plasmonic microstructures at ultralow laser power, which simultaneously enhance electromagnetic sensitivity and enable posture‐adpative surface‐enhanced Raman scattering (SERS) sensing. Notably, the dynamic alignment of Additive‐LIPSS enables robot posture‐dependent SERS signal modulation with 5‐fold intensity variation which allows real‐time feedback of the robot's posture in complex environments. As a proof of concept, the functionalized milli‐robot is demonstrated for on‐demand gastric cancer detection, highlighting its potential for real‐time, non‐invasive diagnostics. Our on‐demand functionalization approach thus offers a versatile and scalable platform for next‐generation multifunctional robotic systems.