Capsule robots are promising tools for minimally invasive diagnostics and therapy, with applications from gastrointestinal endoscopy to targeted drug delivery and biopsy sampling. Conventional magnetic capsule robots embed bulky permanent magnets at both ends, reducing the usable cavity by about 10-20 mm and limiting integration of functional modules. We propose a compact, 3D-printed soft capsule robot with a magnetic coating that replaces internal magnets, enabling locomotion via a thin, functional shell while preserving the entire interior cavity as a continuous volume for medical payloads. The compliant silicone-magnetic composite also improves swallowability, even with a slightly larger capsule size. Magnetostatic simulations and experiments confirm that programmed NSSN/SNNS pole distributions provide strong anisotropy and reliable torque generation, enabling stable bidirectional rolling, omnidirectional steering, climbing on 7.5 degree inclines, and traversal of 5 mm protrusions. Rolling motion is sustained when the magnetic field at the capsule reaches at least 0.3 mT, corresponding to an effective actuation depth of 30 mm in our setup. Future work will optimize material composition, coating thickness, and magnetic layouts to enhance force output and durability, while next-generation robotic-arm-based field generators with closed-loop feedback will address nonlinearities and expand maneuverability. Together, these advances aim to transition coating-based capsule robots toward reliable clinical deployment and broaden their applications in minimally invasive diagnostics and therapy.

翻译：胶囊机器人是微创诊断与治疗领域极具前景的工具，其应用范围涵盖胃肠内窥镜检查、靶向药物递送及活检采样等多个领域。传统磁驱动胶囊机器人通常在两端嵌入体积较大的永磁体，导致可用腔体减少约10-20毫米，限制了功能模块的集成。本研究提出一种采用磁涂层替代内置磁体的紧凑型三维打印软体胶囊机器人，通过功能性薄壳实现运动驱动，同时将整个内部腔体保留为连续空间以容纳医疗载荷。该柔性硅胶-磁性复合材料即使在外径稍大的情况下仍能提升吞咽舒适度。静磁仿真与实验证实，通过编程设计的NSSN/SNNS磁极分布可产生强各向异性与可靠转矩，实现稳定的双向滚动、全向转向、7.5度斜坡攀爬及5毫米凸起跨越能力。当胶囊所处磁场强度达到0.3 mT时（在本实验装置中对应30毫米有效驱动深度），滚动运动可持续进行。未来研究将优化材料成分、涂层厚度与磁极排布以提升输出力与耐久性，而基于机械臂的新一代闭环反馈磁场发生器将解决非线性问题并扩展操控性能。这些进展共同推动涂层式胶囊机器人向可靠临床应用的转化，拓展其在微创诊断与治疗领域的应用前景。