Development of Workspace-creation manipulator for minimally invasive neurosurgery (mechanical design of the manipulator and evaluation experiment)

This paper presents the Workspace-creation manipulator, a multi-DOF brain spatula type manipulator for minimally invasive neurosurgery. We show the mechanical design of the manipulator and evaluation of its function. The manipulator design specification is decided in consideration of newly operative procedure by using micromanipulator system through a 20 mm diameter cranial hole and operating room constraints. The tip of the manipulator is 2 mm thickness, 7 mm width, 110 mm length and has 10-DOF serial link manipulator which is able to be inserted from small cranial hole and follow the brain shape. The Positioning manipulator has an active prismatic joint and 5 passive joints with tendon length compensation method. Tendon length compensation method is based on three techniques, using rolling contact, parallel linkage, and moving pulleys, and we confirm the effectiveness of the tendon length compensation method through tendon tension force measurement experiment. To evaluate the mechanical design effectiveness, we execute an in vivo experiment using pig brain. We are easily able to set the system because of its lightness and compactness, and we insers it between the dura mater and cerebrum smoothly, and workspace in the brain is secured. We think this result shows the availableness of the mechanical design of the manipulator.