Multi-degree-of-freedom Bending Mechanisms and Drive Mechanisms for Robot-Assisted Minimally Invasive Microsurgery*

Minimally invasive surgery (MIS) reduces patient burden and considerably enhances quality of life. However, it requires surgeons with advanced skills. To address this, remote-controlled surgical robots for laparoscopic procedures have become common in clinical practice. The use of these robots is also expected to expand into the field of microsurgery in the future. Currently, while there are robotic systems available for microsurgery in open environments, minimally invasive robotic systems designed for extremely narrow spaces and microsurgery have not yet been widely adopted in clinical settings. Remote-controlled (leader-follower-type) manipulator systems are a promising solution for achieving robot-assisted minimally invasive microsurgery (MIMS), similar to their application in laparoscopic surgery. Our previous work includes the development of a handheld device—a robotic intraocular snake equipped with a microgripper. The robotic intraocular snake features a user interface that allows accurate control of the microgripper at its distal end. This study introduces multi-degree-of-freedom (DOF) bending and drive mechanisms for robot-assisted MIMS. We present examples of these mechanisms with an insertion diameter of less than 0.9 mm, designed for use in narrow areas in body cavities. Notably, we have developed a mechanism with enhanced flexibility, including a 4-DOF bending mechanism, a roll axis for the forceps shaft, and an end-effector. We subsequently fabricated an actual-scale prototype and tested its fundamental functions, including the 4-DOF bending capability, rotational movement of the forceps shaft, and the grasping function of the instrument unit driven by motors. Despite identifying areas for improvement and challenges, the testing confirmed the feasibility of achieving robot-assisted MIMS. In our opinion the proposed mechanism and technology can be applied not only to MIMS, but also to other areas of microtasks.