RIASSUNTO
In the detection of dissolved oxygen(DO) concentration based on the principle of fluorescence quenching, fluorescence intensity detection generally relies on high-precision instruments, extra amplifier circuits and filter circuits at present, which make the detection cost high and the structure complex. In order to reduce the detection cost, simplify the structure of the detection system and improve the stability of the detection, a method of directly detecting the fluorescence intensity using the light-to-frequency proportional conversion characteristics of TCS3200 sensor was proposed and a DO concentration detection system was designed subsequently. The linear relationship between the output frequency of the sensor and the DO concentration was studied and established, based on which the sample DO concentration can be calculated by using the frequency value collected in the detection system accordingly. The experimental results show that the relative error (RE) between the measured DO concentration and the standard value of the sample is less than 5%, and the relative standard deviation (RSD) of the sample data is less than 2%, both of which meet the requirements of accuracy and precision respectively. At the same time, the detection system avoids complicated circuits and its structure is simple, and has the merit of strong anti-interference ability, low cost and high precision.