Development of Deployable Bending Wrist for Minimally Invasive Laparoscopic Endoscope

During the last two decades, minimally invasive surgery (MIS) has become popular because it offers advantages such as less pain, faster recovery, improved cosmesis, and reduced complications. Single-port laparoscopic surgery is a form of MIS where surgeons operate exclusively through a single entry. However, the view from the rigid endoscope is often obscured by the instruments which pass through the same single entry. To remove the need for a secondary viewing port and the blind spots during operation, we propose a deployable wrist mechanism for minimally invasive laparoscopic surgery. It utilizes an S-shape nitinol tube with a curvature of 15 mm and 1.83 mm in diameter. When retracted, the s-shaped wrist is straightened into the main shaft of the laparoscopic tool. As the wrist translates outward, the S-shaped nitinol wrist emerges from an opening on the tool shaft and bends to point at the tooltip. The wrist has two degrees of freedom: translational displacement for controlling the bending and rotational movement of the wrist. The bending mechanism was analyzed by finite element method simulation and validated by experiments. For future work, we will try to widen the scope of its applications including laser ablation tools, triangularization, and other microsurgical procedures.