Development and verification of a micro magnetically guided helical robot with active locomotion and steering capabilities for guidewires

As a fundamental instrument in vascular interventional surgery, guidewires inherently face limitations when navigating through complex curved blood vessel bifurcations due to their deflection and the constraints of external pushing and twisting operations. To address this issue, this study proposes a micro magnetically guided helical robot comprising a cylindrical permanent magnet, a helical casing, a soft structure, and an interventional guidewire. The soft structure is employed to enhance the steering capability of the guidewire by reducing resistance caused by its deflection during steering. Furthermore, an additional helical casing with a permanent magnet is added at the head of the guidewire to enable active movement. The effectiveness of the experimental platform was validated using a T-shaped magnet, with a maximum error of less than 3°. A prototype of the magnetically guided robot was fabricated, and basic experiments were conducted in various liquid environments. Steering tests were performed in a 2D plane, demonstrating that with the assistance of the soft structure, the robot achieved an additional 32° of bending beyond the maximum initial bending degree, resulting in a maximum bending of 90°. Moreover, the active locomotion and steering capabilities of the magnetically guided robot were validated in various in vitro simulated blood vessels. The study effectively demonstrated the successful execution of selective steering motion, continuous steering motion, and large-angle bending motion by the robot, utilizing a variety of glycerin-filled tubing configurations, such as Y-shaped, Ω-shaped, and U-shaped tubing, as representative models to simulate iliac artery, aortic arch, and distal coronary arteries encountered in the femoral artery intervention pathway. These experiments confirmed the effectiveness of the proposed robot in enabling the guidewire to navigate through curved blood vessels.