Chronic total occlusion is a critical complication of coronary artery disease and peripheral arterial occlusive disease. Where reperfusion therapy removes the obstacles in the vessel and restores the blood flow is one of the critical operations in the procedure. Especially, for the revascularization in small vessels such as coronary arteries, we present a guide-wired helical microrobot mimicking the corkscrew motion for mechanical atherectomy that enables autonomous therapeutics and minimizing the radiation exposure to clinicians. To achieve this goal, we designed and fabricated the helical shape robot of 7.5 mm length and 0.8 mm radius with a spherical joint and a guidewire. We implemented an external electromagnetic manipulation system capable of high power and frequency and an autonomous guidance motion control including driving and steering including motion feedback through X-ray angiography.
We validated the performance of the prototyped system through both in-vitro and in-vivo experiments under clinical settings. The devised approach enables us to navigate the helical robot to the target area and successfully unclog the thrombosis under the 3D printed channel mimicking vessels and bifurcation. For the in-vivo validation in rat models, an artificial thrombus was fabricated and placed in a small-size vessel by using gelatin, and, finally, atherectomy procedures are successfully conducted for the cases of well-formed artificial thrombus. This technology overcomes several limitations associated with a small vessel environment and promises to advance medical microrobotics for real clinical applications while achieving intact operation and minimizing radiation exposures to clinicians. Advanced microrobot based on multi-discipline technology could be validated in vivo for the first time and that may foster the microrobot application at clinical sites.