Cross‐Scale Hierarchical Targeted Delivery System Based on Small‐Scale Magnetic Robots

Magnetic microrobots (MMRs) and continuum robots, particularly magnetic continuum robots (MCRs), exhibit potential for targeted drug delivery. However, practical applications are restricted by the relatively low locomotion speed of MMRs relative to the human body scale and the large size of MCRs, which limits navigation through narrow internal vessels and cavities. Integrating these two systems enables complementary advantages and broadens the applicability of targeted delivery. In this review, this integrated approach is referred to as a cross‐scale hierarchical targeted delivery system based on small‐scale magnetic robots. The system consists of four main modules: the MMR module, the MCR module, the magnetic actuation and control module, and the imaging and feedback module. According to the operational process, the system is divided into two subsystems: (1) the first‐stage targeted delivery system based on MCRs, which navigates within the human‐scale environment through large vessels to reach the lesion vicinity or narrow pathway entrances to release MMRs and (2) the second‐stage targeted delivery system based on MMRs, which utilizes magnetic actuation to deliver the MMRs precisely to the target area for controlled local drug release. This review systematically discusses the core functionalities required for both subsystems, summarizes recent advances in their implementation, analyzes the latest research progress on clinical applications, and presents the challenges and future development trends of each module.