In Situ Pixel-Scale Magnetic Programming 3-Dimensional Printing for Multimode Soft Miniature Robots with Multifunctions

Magnetic microrobots with noncontact and real-time control capabilities have garnered marked attention for targeted drug delivery in narrow, enclosed pathways within the human body. The manufacturing method of these magnetic robots plays a crucial role in determining their functionality. In this study, a photocuring 3-dimensional (3D) printing technique with in situ pixel-scale magnetic programming was developed, enabled by a 3D large-scale uniform magnetic field generator with a high strength of approximately 50 mT. Magnetic particles were rotated and aligned on demand to print intelligent structures with a spatial resolution of 50 μm. A novel key-node splicing magnetization method was introduced to control multicurved deformations in 1D strips and 2D membrane magnetic robots, enabling various modes of locomotion, such as rolling, creeping, swimming, and patch-based drug release. To support additional functions, 3D spatial magnetization was implemented for customized spiral capsule robots, allowing precise multidirectional swimming and multitarget droplet-based drug delivery. These multimode and multifunctional magnetic actuators were validated through in vivo operations in confined environments such as the gastrointestinal tract and bladder.