Force Model for Ultrasonic Needle Insertion

A better understanding of needle-tissue interaction forces when needle is inserted into tissue during injection and minimally invasive surgery can lead to more accurate needle placement, better needle path planning, and better surgical simulation. In this study, a vibratory needle insertion force model is experimentally developed to explore the effect of ultrasonic amplitude on the insertion force. The maximum insertion force is comprised of three forces: tearing force, spreading force, and friction force. Ultrasonic vibration needle insertion experiments are performed on a tissue simulant to measure how vibratory parameters influence friction force, dynamic fracture toughness, and crack length. Results show that with the vibration amplitude changing from 0 to 517.2 μm, the maximum puncture force reduces up to 60.8%, the friction force reduces up to 80.7%, the dynamic fracture toughness of the phantom decreases up to 76.8%, and the crack length increases up to 325.8%. The increase in crack length created by the high amplitude vibration allows for the substantial decrease in frictional force.