Optical fiber sensor for soft tissue investigation during minimally invasive surgery

This paper describes the preliminary design and construction of an optical fiber sensor which has been developed for evaluating the feasibility of using an optical-based force sensing methodology to investigate mechanical soft tissue properties during minimally invasive surgery. This sensor applies a novel reflective light intensity modulation scheme using bent-tip optical fibers and a reflector to measure mechanical response of the soft tissue when it interacts with the sensor. By adopting such optical fibers to detect minute deflection of a flexible cylindrical structure at the reflective edge of the reflector, good sensitivity for the force detection can be obtained. The prototype described in this document has demonstrated that it can detect the tissue interaction forces in the axial direction and identify variations in tissue stiffness. The maximum force range that can be detected by the sensor is 3 N. The measurement resolution is 0.02 N.