Water Quality Monitoring Using Fibre Bragg Grating Sensors

Abstract

The quality of water is an important factor in human health, ecosystem balance, and sustainable development. The growing presence of contaminants such as heavy metals and bio-pathogens in water bodies poses significant challenges, necessitating the development of innovative and reliable monitoring technologies. Traditional methods, including spectroscopic, electrochemical, and molecular techniques, often suffer from limitations such as high cost, complex operation, lack of real-time capabilities, and inadequate portability, which make them impractical for widespread and continuous monitoring. This thesis focuses on the design, development, and application of Fibre Bragg Grating (FBG) sensors for water quality monitoring, specifically targeting the detection of cadmium (Cd), chromium (Cr), and the bio-pathogen Salmonella typhi. FBG sensors, originally developed for telecommunications, exhibit unique advantages, including high sensitivity, robustness, immunity to electromagnetic interference, and the ability to operate in harsh environments. This research leverages these attributes to develop tailored FBG sensors for environmental applications. The work encompasses the functionalization of clad etched FBG surfaces using nanostructured coatings to improve their specificity and sensitivity towards the targeted contaminants. The functionalized, clad etched FBG sensors have been used to sense cadmium, chromium and Salmonella typhi. The sensors' performance is rigorously characterized, including optimization of coating parameters, evaluation of response time, detection limits, and selectivity. Further, the efficacy of the sensors in real water samples has been demonstrated, which illustrates the ability of FBG sensors to detect trace levels of heavy metals and pathogens with high accuracy and minimal interference. Comparative studies undertaken with established methods underscore their superior operational stability, real-time monitoring capabilities, and cost-effectiveness. Furthermore, the FBG sensors’ multiplexing potential facilitates simultaneous detection of multiple contaminants, offering a comprehensive solution for water quality assessment. The findings presented in this thesis establish Fibre Bragg Grating sensors as a transformative technology for water quality monitoring. By addressing key limitations of existing methods, these sensors provide a reliable, scalable, and portable platform, contributing significantly to public health and environmental sustainability.