The Study Of Optical Dissolved Oxygen Detector Based On Fluorescence Quenching

With the rapid development of industry and agricultural of World,huge amounts of waste water from them were flowing into the sea and rivers,and industry waste gas also made some pollution to water indirectly,all the above make the problems of shortage and pollution of water resources more obvious.So the surveillance of waste water must be taken into act as soon as possible.The concentration of dissolved oxygen is an important index,it deceases when water is polluted.So the apparatus of dissolved oxygen should be invented to check the situations of different places and then do some related fixing work.Most of apparatus are based on Clark electrode(current check),which is faster than idometric,swifter,and work independent,so as to check continuously outside.But the water samples need to be churned when checking because the membrane and electrode would like to age while consuming oxygen too,that need to be activated and changed often. In the foreign market there is a kind of oxygen detector based on fluorescence quenching, which could check fast and consumes no oxygen,it also have a long lifetime that could be used as long time surveillance.The paper founded on fluorescence quenching effect of oxygen to check the oxygen concentration.In the experiment Ru(ph2phen)₃²⁺ was used as fluorescence sensor,which will emit strong pink fluorescence when excited by blue light,then quenched by dissolved oxygen,so the concentration could be calculated by checking the density of fluorescence. On the bases above,a dissolved oxygen checking apparatus was invented to check water continuously online.The primary works in this paper are:(1) Expressed the framework of system,designed functional modules and set hardware configuration,printed hardware principle chart and PCB diagram which were made into circuit board.(2) Based on circuit board,printed flow chat of every module in MCS-51 single-chip processor program.Designed lower program and debugged using C51 language.Made RS-232 communication protocol to connect between single-chip processor and PC. Developed upper C++ program for deeper processing of the data.Based on ADO technology,connected to SQL2000 database using Visual C++.(3) Did experiments of hardware modules and software debugging,temperature sensitive of sensor membrane,while got the statistic of temperature feature and corrected the result.Compared with idometric and analyzed the features and precision of the apparatus. (4) Developed a novel dissolved oxygen detector,where precision is 0.2 mg/L,and stability within 4.7%,it could be used wild spread as a agricultural water quality detector in benefit of agricultural productivity and modernization.