Research on TOC Sensor Based on Lock-in Amplifier

Total organic carbon (TOC) is the crucial metric for representing the total organic matter content in water, and its detection provides a comprehensive assessment of organic pollution levels in aquatic bodies. The TOC sensor designed in this paper leverages Beer-Lambert Law and Lock-in amplifier (LIA) technology, utilizing 254nm ultraviolet optical as the detection source and green light as compensation to eliminate the impact of turbidity, extracting the ultraviolet signal to achieving accurate TOC concentration measurements. Additionally, thermoelectric cooler (TEC) temperature control addresses temperature drift caused by heat accumulation during prolonged operation in enclosed environments. The test results show that the absolute error is less than 2%FS, and the linearity is 0.1%, which meet the technical requirements for TOC online monitoring in complex environments