In vitro validation of clearing clogged vessels using microrobots

We achieve mechanical grinding of blood clots using helical microrobots with average diameter of 300 μm inside catheter segments. The helical microrobot is steered and propelled under the influence of rotating magnetic fields (20 mT). These fields are generated using a magnetic-based robotic system with two rotating dipole fields. First, we analyze the optimal configuration of the rotating dipole fields with respect to the helical microrobot to maximize the efficiency of the grinding. This analysis is done using gelatin thrombus model. Not only do we find that an offset (distance between the rotating dipole fields and the dipole of the microrobot) of 15 mm exerts an additional magnetic force to assist the grinding, but we also observe that the drilling time through the thrombus model is decreased by 39%. Second, we prepare blood clots and develop an image processing algorithm to calculate the size of the blood clot during drilling. The drilling decreases the size (disk shaped clots with diameter and length of 3 mm and 5 mm, respectively) of the blood clot by approximately 50% in 36 minutes. The demonstrated in vitro grinding experiments using helical microrobots provide broad possibilities in targeted therapy and biomedical applications.