Modeling cutting force of laparoscopic scissors

Modeling forces applied to cut biological material with laparoscopic scissors is important for haptic rendering in laparoscopic surgical simulation. The cutting process is characterized in deformation and fracture. An analytical model for cutting human iliac artery with laparoscopic scissors is derived with concepts of shearing deformation and fracture mechanics in this study. An experimental set-up was built to verify the analytical cutting force model. Three pieces of human iliac artery were cut with laparoscopic scissors. Force required to cut arterial wall and corresponding angular displacement of scissors' handle were collected to evaluate the parameters in the cutting force model. The cutting force model is able to fit the average normalized force-handle angle curve with coefficient of determination equals to 0.977. The starting point of fracture is modeled by energy based fracture mechanics method. The energy based method predicts the fracture point with only 3% deviation from the manual determination.