Investigation of U-shaped plastic optical fiber as refractive index sensor for liquids assessment

In this study, U-shaped fiber optic sensors are fabricated and analyzed to measure the sensitivity of the developed sensor and optimized the detection of the refractive index (RI) of a given liquid. Identifying the authenticity of the RI is very important in food processing, chemical, liquid security and pharmacy. In this research, three types of sensors with different curvature radii (3 mm, 4 mm, and 5 mm) and different angles (30°C and 60°C) with 60 cm length of polymer fibers have been developed to characterize and analyze which type of sensor that will give optimal reading. This sensor is expected to be used for future studies such as in bioengineering, food and liquid security and chemical detection. Each sensor is tested with several types of liquids that have different densities. The development of this RI sensor is also intended to detect a suitable temperature for RI of a liquid that is between 20°C - 55°C. The research analyzed the RI sensitivity using impurity-free liquid (mineral water) and non-impurity liquid (saline water and used cooking oil). The result is measured and collected using Optical Power Meter and a 6500-input light source. The selection of this U-shaped sensor is due to the robustness of this sensor in various environments, high sensitivity, and its simple construction. This work aims to produce a low-cost and highly optimal U-shaped sensor for detecting and measuring the RI of a liquid impurity and security in any environment.