Fiber Bragg gratings embedded in 3D-printed patches for sensitivity enhancement of deformation monitoring

In this work, we present and discuss on the sensing properties of a 3D printed patch embedding a fiber Bragg grating (FBG). In the paper, we first describe the fabrication process of the proposed sensing device and then we analyze its performance in terms of thermal sensitivity and deformation detection capability. In particular, FBGs were embedded in polylactic acid (PLA) rectangular patches that confer greater strength to the bare FBG and enhance their sensing capabilities. We show that the patch thickness, by increasing the distance between the optical sensor and the neutral axis of the structure where it is fixed, provides a gain factor in the device sensitivity to deformation. These results encourage the application of FBGs embedded in 3D-printed patches in the field of the structural monitoring where, by efficiently selecting patch dimensions, in particular the thickness, it is possible to improve the sensor robustness and, contemporary, the deformation sensitivity with respect to bare FBGs.