Hydrogel Thin‐Film Magnetic Millirobots with Programmable Deformation and Shape Retention for Biomedical Applications

Soft millirobots capable of controlled deformation and rapid responsiveness are gaining prominence in biomedical applications, particularly for precise drug delivery. This study presents a novel triple‐layered hydrogel thin‐film magnetic millirobot (HTFMR), constructed from two non‐toxic Parafilm layers and a biodegradable hydrogel infused with silica‐coated NdFeB magnetic particles. The HTFMR exhibits complex shape‐controllability and shape‐retention properties, making it highly effective for cargo transport. Under programmed magnetic fields, its four‐arm configuration enables efficient and secure grasping and cargo release at designated locations, with its shape‐retention capability enhancing transport stability. In its four‐claw configuration, the robot adheres firmly to surfaces, enabling targeted drug delivery to specific regions such as the gastric and intestinal mucosa. Cytotoxicity evaluations confirm the HTFMR's excellent biocompatibility. Furthermore, the robot is visible under X‐ray imaging, and its precise movement and shape control within an electromagnetic actuation system demonstrate reliable performance under biologically simulated conditions.