Temperature-Compensated Optical Fiber Force Sensing at the Tip of a Surgical Needle

A Fabry-Perot interferometric (FPI) sensor based on interferometric intensity-phase modulation is proposed for in vivo force sensing at the tip of a surgical tool for minimally invasive surgeries. To address significant thermal influence, a temperature compensation solution is first developed where two FPI sensors are used, one being subjected only to temperature variation and used to compensate for the temperature influence of the second sensor. The sensing system is then designed and finally characterized experimentally. In this paper, the two fabricated FPI sensors are identical to 400 μm in outer diameter, and embedded into the tip of a puncture needle that has an inner diameter of 1.54 mm. The sensing system is calibrated by a commercial dynamic force sensor. Results show that the temperature-compensated FPI sensing system has a measurement range of 0-8 N with a resolution of 0.3 N at temperature of 23°C-37.5 °C. Insertion experiments with phantom skin tissue at different temperatures show the thermal effect is compensated.