High‐Performance Magnetic FePt (L1₀) Surface Microrollers Towards Medical Imaging‐Guided Endovascular Delivery Applications

Abstract Controlled microrobotic navigation in the vascular system can revolutionize minimally invasive medical applications, such as targeted drug and gene delivery. Magnetically controlled surface microrollers have emerged as a promising microrobotic platform for controlled navigation in the circulatory system. Locomotion of micrororollers in strong flow velocities is a highly challenging task, which requires magnetic materials having strong magnetic actuation properties while being biocompatible. The L1₀‐FePt magnetic coating can achieve such requirements. Therefore, such coating has been integrated into 8 µm‐diameter surface microrollers and investigated the medical potential of the system from magnetic locomotion performance, biocompatibility, and medical imaging perspectives. The FePt coating significantly advanced the magnetic performance and biocompatibility of the microrollers compared to a previously used magnetic material, nickel. The FePt coating also allowed multimodal imaging of microrollers in magnetic resonance and photoacoustic imaging in ex vivo settings without additional contrast agents. Finally, FePt‐coated microrollers showed upstream locomotion ability against 4.5 cm s⁻¹ average flow velocity with real‐time photoacoustic imaging, demonstrating the navigation control potential of microrollers in the circulatory system for future in vivo applications. Overall, L1₀‐FePt is conceived as the key material for image‐guided propulsion in the vascular system to perform future targeted medical interventions.