Magnetically Actuated Milli-Scale Voxel Robot for Navigation in Tubular and Anatomical Environments

초록

Untethered milli-scale robots hold promise for navigating confined biological pathways and delivering localized interventions, yet existing designs often rely on solid geometries or modular assemblies that limit robustness, payload capability, and locomotion versatility.A single-unit milli-scale voxel robot is introduced, featuring a cuboctahedral open-frame architecture with strategically embedded permanent magnets that enable lightweight construction, internal payload capacity, and multiple locomotion modes without onboard actuation. We demonstrate two robust magnetic locomotion strategies—pivot walking and tapping—inside tubular environments of varying diameters and inclinations. Quantitative experiments reveal that pivot walking achieves the highest balance of speed and stability, with consistent motion up to a 7.5◦ incline under both unloaded and payload-carrying conditions in air and water conditions. Magnetic field uniformity across the workspace was validated through triaxial sensor measurements and COMSOL simulations, confirming actuation feasibility. The voxel robot further demonstrated reliable navigation through a 3D-printed human ear model, highlighting potential for minimally invasive anatomical procedures. Compared to prior modular milli-scale robots, the proposed voxel design eliminates inter-module failure modes while enhancing adaptability, functional versatility, and clinical relevance.

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