Optical fiber axial contact force sensor based on bubble-expanded Fabry-Pérot interferometer

An optical fiber axial contact force sensor based on bubble-expanded Fabry-Pérot interferometer (FPI) is investigated in this paper. The FPI is packaged as a reflective sensing probe to measure the axial contact force which is applied on the end of sensing probe. To the best of the authors' knowledge, this is the first time that intrinsic optical fiber FPI is used for axial contact force measurement, which has potential in application fields such as robotics. The sensing probe based on bubble-expanded FPI exhibits a high axial contact force measurement sensitivity of −750.17 pm/N, which is 3 times higher than that of the sensing probe based on traditional rectangular FPI fabricated in this work. This experimental results are well explained by the simulation analysis using Comsol software. The proposed optical fiber axial contact force sensor has advantages of compact size, simple structure and high sensitivity.