Development Of Water PH Sensor Using Plastic Optical Fiber

Abstract

This project investigates the development and performance of a U-shaped Plastic Optical Fiber (POF) sensor designed for real-time water pH monitoring. The proposed sensor offers a low-cost, durable, and robust solution to overcome the limitations of traditional glass electrode-based pH sensors, which are fragile, require frequent calibration, and are impractical for continuous, real-time monitoring in harsh environments. By utilizing the evanescent field interaction between guided light and a pH-sensitive coating applied to the exposed region of the fiber, the sensor detects pH changes through measurable shifts in light intensity and wavelength. The experimental setup includes a broadband light source, a U-shaped POF sensor, a spectrometer, and AvaSoft 8 software for data collection. Buffer solutions with pH values ranging from 4.0 to 9.18 were used to test the sensor’s response. The results show that the sensor with the 1 cm exposure demonstrated strong sensitivity, repeatability, and a clear linear correlation between pH levels and the spectral response, particularly within the 530–600 nm wavelength range. The findings suggest that the U-shaped sensor can provide an affordable, real-time alternative to existing pH measurement technologies, with potential for future improvements in sensitivity, temperature compensation, and integration with IoT systems for remote monitoring.