Mini-system for monitoring water quality using fluorescence

Abstract

This thesis presents the design and development of a compact fluorescence detection system for monitoring the integrity of reverse osmosis (RO) membranes based on specific fluorescence responses of target pollutants. Given the inherent weakness of fluorescence signals, a signal processing architecture is proposed that integrates photodiode detection, preamplification, and a lock-in amplifier circuit centered on the AD630 chip to extract low-level signals with high reliability. The system’s optical path is optimized through ZEMAX simulation to achieve efficient excitation and collection within a compact elliptical chamber. A custom 3D structure and printed circuit board (PCB) were developed to house and support the optical and electronic components. Experimental and simulation results confirm that the system demonstrates promising signal-to-noise characteristics. This work lays the groundwork for a practical and economical tool for membrane performance monitoring and provides a foundation for future integration with remote communication modules for industrial application.