Three-dimensional force sensors based on all-fiber Fabry–Perot strain sensors

A novel three-dimensional (3D) force sensor based on an ultrasensitive all-fiber extrinsic Fabry–Perot (FP) strain sensor and a paperclip-shaped elastomer is proposed and demonstrated. Three FP strain sensors, fabricated by a 157 nm laser micromachining system, are respectively bonded on the three induction beams of the elastomer for sensing their strain variations induced by different direction forces (Fx, Fy, Fz). The measured forces are calculated by the combination of a 3 × 3 calibration matrix and the least squares iterative method. Finite element simulation analysis and experimental results both show the 3D force sensor has perfect linearity with better than 0.999 and low crosstalk. Moreover, the experimental results indicate it exhibits a high-repeatability precision of 3D force measurement with less than 0.8%. The 3D force sensor based on the FP strain sensors is reported for the first time, and it offers an extreme potential suitable for 3D force measurements in the field of structural health monitoring and robotic.