Design and Evaluation of a Sterilizable Force Sensing Instrument for Minimally Invasive Surgery

Although the inability to feel tool-tissue interaction forces during minimally invasive surgery (MIS) has been recognized as a significant difficulty encountered by surgeons during these procedures, existing sensorized technologies have not yet been approved for use in humans. The challenges of properly cleaning and sterilizing these instruments prevent them from being operating-room ready. The focus of this paper was to develop a sterilizable instrument that uses strain gauges, the most common force-sensing method, to measure the tool-tissue interaction forces in three degrees of freedom (DOFs) during MIS. A series of experiments is conducted to identify cables and connectors, as well as strain gauge adhesives and coatings to allow the instruments to successfully withstand autoclave sterilization. This resulted in the construction of a final prototype capable of measuring forces in three DOFs, which was able to withstand six sterilization cycles with good sensing performance (0.15-1.70 N accuracy, 0.02-1.20 N repeatability, and 0.11-1.05 N hysteresis depending on the measurement direction). This paper demonstrates that autoclave sterilization is possible for a strain-gauge instrumented device and can lead to more advances in the development of sensorized instruments for surgery and therapy.