A High-sensitivity Three-Dimensional Force Sensing Sensor for Minimally Invasive Cardiac Ablation Surgery

This paper introduces a high-sensitivity distal three-dimensional force sensor designed for cardiac ablation surgery. The sensor combines a force-sensitive structure with fiber Bragg gratings (FBGs) for the measurement of triaxial forces. At the tip of the sensor, an elastic flexure structure is designed, with four pairs of symmetrically arranged U-shaped slots for axial force perception and a modified I-beam structure for lateral force measurement. Five FBG elements are embedded into the elastic flexure structure, with each FBG placed in a tightly suspended manner and fixed at both ends using an adhesive to detect micro-strain and ensure sensitivity. The theoretical force-strain relationship is derived, and decoupling methods are provided. Simulation experiments based on finite element modeling are conducted for static calibration analysis. Simulation results indicate that under axial forces ranging from 0 to 2N, the axial force resolution is 4.46mN, and under lateral forces ranging from -1 to 1N, the lateral force resolutions in the two directions are 0.294mN and 0.293mN, respectively. These findings demonstrate that the sensor exhibits high sensitivity, validating the effectiveness of the design.