Abstract
In this study, a novel high-reliability liquid leakage sensor with a V-shaped defect coupling structure (VDCS) is proposed and experimentally demonstrated using polymer optical fibers (POFs) based on a light-emitting diode (LED) side-coupled light source. Liquid leakage detection is achieved with changes in the refractive index as the coupling medium transforms from air to liquid. The LED lamp both provides a light source and assists positioning. The coupling efficiency of the POF liquid leakage sensor varies with the depth and angle of the VDCS. Experimental results show that the coupling efficiency of the POF leakage sensor is high when the VDCS depth is 0.5 mm and the inclination angle is 60°. Compared to an existing leakage sensor with a hole-shape defect coupling structure (HDCS), the VDCS has a faster response time and higher reversibility. The average reliability of the liquid leakage sensor is increased to 5.92 μW/mL. This research provides a powerful structural reference for POF side-coupling leak measurement and can also be applied to the fields of gas and humidity sensing.
Highlights
LEAK detection has important applications in semiconductor factories and power facilities, among other locations
The focus of this research is the component of light propagating in the vertical direction of the V-shaped defect coupling structure (VDCS); our team previously examined light propagating in the horizontal direction of the hole-shape defect coupling structure (HDCS) [25]
When the medium in the VDCS is air, we assume that line ABC is the light at the critical position where total reflection occurs in the fiber and line DEF is the limiting light with a positive numerical aperture of the light-emitting diode (LED)
Summary
LEAK detection has important applications in semiconductor factories and power facilities, among other locations. The conversion of a liquid leakage event into a change in temperature or strain is time-consuming, which affects the real-time performance of the system Special structures, such as cones [24] and gratings, can be machined on the fiber [15,16], which can improve the measurement accuracy of the sensor and reflect changes in the refractive index. Recent studies have proposed a cost-effective side-coupling method to process a hole-shape defect coupling structure (HDCS) on a multimode fiber that reflects leakage events through changes in the defect coupling structure of the medium. A polymer optical fiber (POF) leakage sensor with a V-shaped defect coupling structure (VDCS) is proposed. Experimental results show that the VDCS has an effective fiber side-coupling structure that provides a better solution for leak detection
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