A sterilizable force-sensing instrument for laparoscopic surgery

Although some technologies have been developed to measure tool-tissue interaction forces during minimally invasive surgery (MIS), none of these technologies have been approved for use in humans. The primary factor preventing the use of sensorized instruments in humans is their inability to withstand the stringent conditions present during cleaning and sterilization. This paper presents a series of experiments that were performed to develop a sterilizable instrument capable of measuring tool-tissue interaction forces in three degrees of freedom using strain gauges. The experiments provided an appropriate choice of cables and connectors, as well as an optimal combination of strain gauge adhesives and coatings that allow the sensors to withstand autoclave sterilization. A prototype of the sensorized instruments was developed and tested. The final prototype was able to withstand a sterilization cycle with excellent results (0.10-0.21 N accuracy, 0.05-0.20 N repeatability and 0.06-0.21 N hysteresis depending on the measurement direction). This work shows that autoclave sterilization is possible for a strain-gauge instrumented device.