Automated Surgical Knot Tying on Mini-Incision with Micro-Suture based on Dual-Arm Nanorobot under Stereo Microscope

Knot tying is an essential task for robotic surgery, which is routinely realized by dual-arm robotic manipulation. Despite the well-established protocol and progress at macro scale so far, there remain challenges to further advance robotic knot tying technique, particularly in terms of decreasing space consumption with better dexterity, higher precision, and well biomechanical compatibility. In this paper, we propose a novel dual-arm nanorobotic system setup for automated knot tying performed on mini-incision under stereo microscope, featured by an additional rotation degree of freedom mounted on each arm. With this setup, an optimized motion trajectory planning under standard knot-tying protocol is also presented in order to support tying knots with shorter and thinner suture. Leveraging the natural advantage of nanorobotics and microscope, the proposed system is capable of tying consecutive throws with micro-suture on mini-incision, like in vascular anastomosis or microsurgery. We successfully evaluated the knot tying system on 2.0 mm wide bionic blood vessel with 30 mm long #8-0 micro-suture. We finally tested the mechanical strength of the knots for potential medical assessment.