Ex Vivo Validation of Magnetically Actuated Intravascular Untethered Robots in a Clinical Setting

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Abstract Intravascular surgical instruments necessitate precise navigation within narrow vessels, requiring maximum flexibility, minimal diameter, and high degrees of freedom. However, existing tools often lack adequate control during insertion due to undesirable bending, which not only limits vessel accessibility but also poses a risk of tissue damage. The advancement of nextgeneration instruments aims to develop hemocompatible untethered devices that achieve precise control through external wireless forces and torques applied from outside the body. However, achieving this goal remains complex due to the challenges involved in testing and implementing untethered magnetic robots (UMRs) in clinical environments. These challenges encompass wireless actuation, non-invasive localization, biocompatibility, control robustness, and effective engagement. In this study, we assess the operational effectiveness of hemocompatible UMRs in clinical settings. We utilize an ex vivo porcine aorta model that accounts for factors such as varying blood-vessel diameters, varying blood flow rates, and the presence of renal aortic side-branches. This comprehensive approach enables us to analyze the robots’ motion dynamics within vessels, closely simulating real physiological and anatomical conditions. Our findings, in the absence of clotting, reveal a consistent linear reduction in UMR swimming speed against increasing arterial blood flow. Furthermore, our experiments showcase the UMR’s ability to generate sufficient force to navigate against a maximum arterial flow rate of 67 mL/min. Using the predicted and observed physical interactions of the UMRs, we effectively demonstrate preliminary proof-of-concept locomotion in a difficult-to-access target site, allowing us to navigate through the abdominal aorta and successfully reach the distal end of the renal artery.

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