Simultaneous actuation and localization of biocompatible untethered magnetic robots inside ex vivo arterial systems

Recent advancements in minimally invasive medicine have spurred a growing focus on non-invasive techniques, highlighting limitations inherent to catheter-based interventions such as size and flexibility. To address these limitations, untethered magnetic robots (UMRs), propelled by magnetic torque and field gradients, for navigating fluid-filled lumens like blood vessels, offer potential as treatment modalities or drug carriers. However, to realize in vivo applications significant challenges need to be overcome, including imaging for control and per-formance assessment, robust actuation methods capable of withstanding physi-ological environments, and ensuring biocompatibility. In this study, we present an X-ray-guided teleoperation system suitable for visualizing hemocompatible UMRs, specifically screw-type variants with affixed permanent magnets, scalable for in vivo applications. Actuation of these UMRs is achieved via a magnetic torque generated using a single rotating permanent magnet (RPM), enabling effective propulsion against blood flow up to 67 mL/min and facilitating a grind-ing action for thrombus reduction, measuring 3.6 mm3 reduction in 30 minutes. The designed teleoperated control scheme enhances the success rate from 56%to 76% during in vitro experiments, which is further validated in ex vivo set-tings navigating from abdominal to renal arteries. Furthermore, we introduce a gravity compensation method utilizing the RPM’s magnetic force, enabling pre-cise three-dimensional motion control exemplified in an in vitro carotid artery model, yielding a success rate of 89%, in navigating between the common carotid artery and into the distal end of the internal carotid artery. This compensation method is extended to support microscale soft-magnetic UMRs, demonstrating swimming with near-zero angle of attack of 0.8◦ ± 0.6◦. Additionally, we demon-strate the adaptability of our system, by applying it to rolling motion biohybrid UMRs, which are navigated successfully through X-ray-guided magnetic fields into both the fallopian tubes of an in vitro human reproductive tract model and into each branch of a trifurcation model. These advancements mark significant progress towards the use of UMRs for in vivo trials, showcasing the potential of UMRs in revolutionizing minimally invasive medical interventions.