Thrombus Removal with Magnetically Actuated Micro-Transformers

Thrombotic disorders rank among the principal global mortality factors. Despite significant advancements in interventional therapy technologies, conventional medical robots remain constrained by rigid architectures and elevated invasiveness, leading to vascular wall stress and frictional injury. Furthermore, these systems face challenges in reconciling the flexibility necessary for untethered navigation with reliable vascular traversal. To overcome these limitations, we present a magnetically actuated Micro-transformers (MAMT) with in situ structural reconfigurability. The microrobot, constructed from shape memory polymer (SMP), leverages the magnetothermal effect of Fe₃O₄ magnetic nanoparticles induced by an alternating magnetic field (AMF). When the temperature surpasses the glass transition temperature (50°C) of the SMP, the robot's structure transitions from its initial rod-like form to a final helical shape. Thus, dual-mode operation is achieved: rod-shaped structures for navigation and spiral-shaped structures for thrombus fragmentation. In the MAMT fabricated in this paper, in a simulated blood environment at room temperature, structural switching could be completed within 148 ± 8 s with AMF, and its shape recovery ratio could reach 92.11%. In the simulated thrombus clearance experiments, the thrombus clearance ratio could reach 52.7%. It can reduce the risk of vascular wall injury and enhance the safety of thrombus removal, offering an innovative solution for thrombus treatment.