Sci‐PM Fri ‐ 05: Effects of coating on friction force during needle insertion in soft materials

摘要

Purpose: Of the three main forces, i.e. stiffness force, friction force and cutting force experienced during needle insertion in soft tissue/material, friction force contributes the major portion. Higher friction force is partly responsible for large deformation/displacement of soft tissues/organs during various medical diagnostic and therapeutic procedures. In this study we investigate the effectiveness of needle coating on friction force reduction. Methods and Materials: We have used three types of 18G brachytherapy needles, two of them coated with Teflon and Carbon. Then we have compared the results with standard commercial needle whose coating is unknown. Needles were inserted by a 6 DOF robotic system in soft material phantoms prepared from polyvinylchloride with 25% softener. A 6 DOF force sensor (Nano25®) was mounted on the end‐effector of the robot. To assess the friction force alone, the needle tips were passed through the phantom; only the cannulas were in contact with the material while the data were recorded. Results: We observed significant reduction, about 34% at both 5 & 100mm/s speed, in friction force on needle with Carbon coating. Some improvement was also noticed with Teflon coated needle, about 15% reduction at both 5 & 100mm/s speed. Discussions: Carbon coating is the most effective in reduction of friction force on the needle. Therefore, one of the solutions to reduce tissue/organ deformation/displacement may be coating surgical needles with Carbon. However, chemical and pathological studies are required before going for clinical trials with Carbon coated needles. Acknowledgement: Work supported by NCI grant R01 CA091763.