Development of a fbg based hoop-strain sensor using 3d printing method

In this study, a hoop-strain sensor was developed by embedding a bare fiber Bragg grating (FBG) sensor inside 3D printed Polylactic Acid (PLA) filament. Fabrication process of the hoop-strain sensor indicates that the initial temperature of the melted PLA is around 50 °C which is obviously lower than the printing temperature of the printer nozzle (around 200°C). A typical residual wavelength was found after the fabrication process of the hoop-strain sensor. The shrinkage deformation of the present sensor was around 208~\mu \varepsilon after fabrication. The hoop-strain sensor was flexible and can be used to measure both circumferential strain change and contact pressure between hoop-strain sensors and cylinders. Calibration tests for elongation measurement indicate that the sensitivity and minimum resolution with respect to strain change are 4.04 nm/% and 3.574~\mu \varepsilon , respectively. The obtained measurement sensitivity and resolution for pressure measurement were 0.0035 nm/kPa, and 0.286 kPa, respectively. The maximum measurement ranges of the hoop-strain sensor for strain and pressure measurement are larger than 1% and 800 kPa, respectively.