Autonomous Sorting of Beads in a 3D Environment Using Levitating Magnetic Microrobots

This work presents a novel approach to autonomously sort passive beads in 3D environments using an untethered levitating magnetic microrobot. The in situ untethered magnetic weighing technique is introduced, where the classification of beads is based on the magnetic force required to levitate the microrobot and the beads. Autonomous sorting is achieved through the integration of motion control, trajectory planning, and action scheduling. Experimental validation is conducted using a nine‐coil electromagnetic actuation system and a microrobot of 3 mm in size. The system demonstrates an average trajectory‐following precision of 0.1 mm. The proposed magnetic weighing enables the detection and classification of carried silica beads of 0.75–1.00 mm diameter by measuring the increase in effective weight with a resolution of ≈1 μN. During the sorting process, all particles with a diameter larger than 0.9 mm are classified as heavy, and all those with a diameter smaller than 0.85 mm are classified as light, demonstrating the effectiveness of the approach. Overall, the proposed system holds significant promise for applications in biomedicine and micromanufacturing, driving innovation in autonomous microrobotics.