Characterization of Intra-abdominal Tissues from in vivo Animal Experiments for Surgical Simulation

The lack of data on in vivo material properties of soft tissues is one of the impediments in the development of realistic surgical simulators. The measurement of these properties is not a trivial task, due to the difficulty of the testing itself and the complexity of tissue mechanical behavior. We have developed a system for measuring the mechanical properties of soft tissues in vivo using a robotic device fitted with a force transducer. We measured the response of soft tissues in intra-abdominal organs including the liver and lower esophagus of pigs by using both static and dynamic indentations. We characterize these properties using nonlinear models as well as a linear model. These material models can be effectively integrated into a simulator to provide the user with realistic visual and haptic feedback.