Development Of Dissolved Oxygen Sensor Based On Fluorescence Quenching Principle

The measurement of dissolved oxygen concentration in water is of great importance to water environment monitoring,aquaculture,industrial production and scientific experiments.Papers in the study of dissolved oxygen measurement principle,as well as dissolved oxygen sensor research status at home and abroad based on the development of fluorescence oxygen sensor based on fluorescence quenching method.The main research contents and achievements are as follows:Based on the Stern-Volmer equation,the relationship between the fluorescence lifetime and the dissolved oxygen concentration in water can be deduced.The phase relationship between the fluorescence lifetime and the fluorescence signal at a certain frequency is deduced.The fluorescence lifetime can be calculated by the phase sensitive detection principle and the Fourier transform.Finally,Dissolved oxygen concentration.The optical structure is designed to ensure that the photodiode is not disturbed by stray light.The mechanical structure of the sensor with good sealing performance and easy installation and fixing is designed,and the installation and adjustment of the sensor are completed.The temperature measurement circuit based on NTC thermistor,photoelectric conversion and amplification circuit based on photodiode and band-pass filter circuit are designed.The hardware circuit of DO sensor is designed and debugged by STM32F103.The program of lower computer based on STM32F103 is written and the functions of sensor detection,data processing,result calculation and RS485 communication are realized.The Windows PC program based on QT is designed and programmed to realize the communication with the sensor,display,Storage,fabric-based measurement and online calibration of the sensor.Based on the sensor,a model of dissolved oxygen concentration calculation,on-line calibration method and temperature correction are established.The sensor performance test of the sensor was completed with accuracy,repeatability and stability.The results showed that the sensor design requirements were met.