An ultra-high sensitivity fluorescence sensor based on fluorescence technology

An ultra-high sensitivity fluorescence sensor with 1 ng/L-level detection limit was developed for water treatment applications, in which fluorescent tracing method is applied by using PTSA (1, 3, 6, 8-pyrenetetrasulfonic acid, sodium salt) to indicate the concentration of water treatment agents. This sensor consists of an optical part for fluorescence excitation and detection, as well as a signal processing and control circuit. The optical part employs a compound parabolic concentrator structure and achieves 6-fold increase in the collected fluorescence intensity. The circuit handles the determination procedures such as LED emission modulation, detector signal processing and concentration determination of water treatment agents. For PTSA with ultrapure water in ultra-low concentration range of 0 – 0.1 μg/L, a detection limit of 7 ng/L is demonstrated. The sensor has benefits of low cost, high accuracy and ease of deployment, which is promising for real-time detection of water treatment agents concentration in industrial cooling water circulation system.