A spiral microrobot performing linear and drilling motions by magnetic gradient and rotating uniform magnetic field to unclog blocked human blood vessels

More than one out of three American adults has one or more types of cardiovascular disease [1]. Occlusive coronary artery disease is one of the main heart diseases that results from plaque buildup in blood vessels, blocking the flow of blood. The most common treatment uses a tapered-tip guide-wire and catheter to unclog the blocked blood vessel, which is very hard to control through twisted and narrow blood vessels [2]. In this type of operation, cardiologists are constantly exposed to radiation from x-rays because they have to monitor the blocked blood vessels and the location of the guidewire and catheter, so they wear lead shielding around their bodies to protect themselves from radiation [3]. Microrobots that are controlled by magnetic fields generated from the Magnetic Navigation System (MNS) have been actively investigated to replace manually controlled conventional guidewires and catheters, eliminating cardiologists´ exposure to radiation. One of the promising microrobots is a spiral microrobot actuated by a rotating magnetic field [4, 5, 6]. However, their spiral microrobots cannot separate navigating and drilling motions, and rotating blades may damage healthy blood vessels while navigating through the blood vessel to reach the target point.