Multi-Core Optical Fibers With Bragg Gratings as Shape Sensor for Flexible Medical Instruments

This paper presents a technique to reconstruct the shape of a flexible instrument in three-dimensional Euclidean space based on data from fiber Bragg gratings (FBGs) that are inscribed in multi-core fibers. Its main contributions are the application of several multi-core fibers with FBGs as shape sensor for medical instruments and a thorough presentation of the reconstruction technique. The data from the FBG sensors are first converted to strain measurements, which is then used to calculate the curvature and torsion of the fibers. The shape of the instrument is reconstructed using Frenet-Serret equations in conjunction with the calculated curvature and torsion of the instrument. The reconstruction technique is validated with a catheter sensorized with four multi-core fibers that have FBG sensors. The catheter is placed in eight different configurations and the reconstruction is compared to the ground truth. The maximum reconstruction error among all the configurations is found to be 1.05 mm. The results show that shape sensing for flexible medical instruments is feasible with FBG sensors in multi-core fibers.