Development of a finger-like mechanism of end-effector for micro surgery.

Neurosurgery had been considered nearly impossible due to its technical difficulty and the danger to its special target organ, but with endoscopic methods, many such surgeries can be made safely through the nose. Endoscopic neurosurgery is limited by available instruments, however, and there remain some areas of the human body inaccessible to standard surgical tools. To overcome some of these limitations, in this study we developed a simple mechanism that could form a high curvature in a narrow space. The end product is a finger-like mechanism consisting of five body parts and four joints. All body parts are connected in series, having a total length of 20mm and a diameter of φ4mm. A four-bar linkage internally connects the body parts and joints, and a nitinol backbone was used to improve repeatability. The first joint is driven by a rod or wire, and the shape of the mechanism is determined by rotating the first joint, because the position of each joint depends on the position of the joint before it. The study verified that an image sensor in the end of the finger-like mechanism has a wider range of view, 210 degrees than a conventional endoscope of 100 degrees. Finally, skull model simulation suggests that this device could be used in real neurosurgical applications.