A Suction-Fixing, Stiffness-Tunable Liver Manipulator for Laparoscopic Surgeries

This paper presents a novel liver manipulator featuring suction fixing, stiffness tuning, and pneumatic actuation. In a liver-manipulation process, the manipulator begins in a low-stiffness state and is then pneumatically actuated to fit suction pads to the liver surface. At this point, the manipulator vacuums external air through the suction pads to adhere to the liver surface and then turns to a high-stiffness state to hold the liver tenaciously. Stiffness tuning is achieved with two cloth-rubber beams, which are contained within a closed elastic tube. Sucking the air between the beams increases the stiffness by 4.2 times. Experimental results demonstrate liver manipulation improvement in terms of holding stability and being less invasive.