Temperature-independent Vibration Sensor Based on Fabry-Perot Interferometer using a Fiber Bragg Grating approach

An innovative vibration sensor based on a Fabry-Perot Interferometer (FPI) using Fiber Bragg Grating (FBG) reflectors has been discussed in this work. The sensor has been designed to be compact and easy to fabricate and independent of temperature, to overcome limitations seen in some previous designs, providing an effective correction for temperature effects in FBG-based FPI (FBG-FPI) sensors. In this approach, light from a broadband source in the wavelength range 1500 – 1580 nm has been used to illuminate the FBGs used (having a reflective peak of 1547.42 nm), employing in this way a light source within the FPI optimum wavelength operating range of 1547.15 nm – 1547.80 nm. The sensor developed in this work has been shown able to capture a 3 kHz burst signal from a signal generator, in 1 Hz, 2 Hz, and 3 Hz intervals. In addition, the research carried out has revealed that the sensor could be used to capture sinusoidal signals at frequencies up to 9 kHz, creating a performance comparable with many existing conventional piezoelectric sensors. The ability to operate regardless of any ambient temperature changes (in the range from 26.5°C (room temperature) up until 80°C), opens the way to use such a sensor system over a wide range of engineering applications taking advantage of the next generation of FBG-based FPIs

Optical fiber Bragg grating (FBG)-based strain sensor embedded in different 3D-printed materials: A comparison of performance

A compact fiber Bragg grating (FBG)-based strain sensor has been developed by embedding an FBG inside a 3D-printed structure, allowing the comparison of FBG responses across different filaments such as polylactic acid (PLA), thermoplastic polyurethane (TPU), polycarbonate (PC), acrylonitrile butadiene styrene (ABS), and nylon. Results have shown that FBG embedded in TPU can be effective in the measurements of mechanical strain, giving a responsivity value of 17.70 pm/cm with outstanding linearity of 98 %. Furthermore, small-scale field testing conducted in below-ground environments has shown that strain sensors based on FBG embedded in TPU are the most effective. They offer a responsivity of 13.9 pm/kg with a small standard deviation and high linearity. Additionally, they have the highest temperature sensitivity value of 15.4 pm/°C compared to the other embedded FBGs. Therefore, for most industrial applications, the FBG embedded in TPU can be considered as an alternative to existing embedment methods for strain sensing applications