3D-printed Tilt Sensor based on an embedded Two-mode Fiber Interferometer

A 3D-printed tilt fiber sensor using a two-mode fiber interferometer (TMFI) as the sensing mechanism has been demonstrated. The TMFI was constructed by splicing single-mode fibers (SMF-28s) at both ends of a two-mode fiber (TMF) to generate a comb-like interference spectrum that is sensitive to bending. A 3D-printed cantilever with a weight attached to one end was used to induce bending as the structure was tilted and by embedding the TMFI onto the 3D printed cantilever, different tilt angles can be measured, as a result of the bending of the fiber. The TMFI exhibited a linear response towards the tilt angles, $\theta $ , with a responsivity of $1\times 10^{-2}$ nm/deg at negative $\theta$ (0 to −90°) and $5 \times 10^{-3}$ nm/deg at positive $\theta$ (0 to 90°), respectively. The sensor was able to detect small angle changes in increments as small as 1° and it performs better than embedded FBG sensors. The tilt sensor proposed has a small formfactor and simple design, as well as being cost-effective and light-weight, thus showing significant potential for a variety of civil engineering applications.