Research On Detection And Sensing Technology Of Three-electrode Micro-dissolved Oxygen

In liquid environment,many chemical,biological and physiological processes are inseparable from the participation of oxygen,so the monitoring and control of dissolved oxygen plays an extremely important role in environmental monitoring,sewage treatment,biological fermentation,aquaculture,industrial production,and clinical medical diagnosis.This paper introduces the principle and latest research progress of several dissolved oxygen detection methods,and develops and improves a three-electrode micro-dissolved oxygen sensor based on the electrochemical dissolved oxygen sensor detection principle.The main works are as follows:1.Based on the laboratory conditions,the preparation of dissolved oxygen sensor and the design of detection hardware system were completed.The preparation of dissolved oxygen sensor includes gold working electrode,silver auxiliary electrode,platinum silver protective electrode,electrolyte,oxygen permeable membrane,and the preparation of the cavity and shell structure of the sensor.The design of detection hardware system includes power circuit design,polarization voltage circuit,sensor signal conversion and amplification circuit design,A/D conversion circuit design,MCU circuit design and LCD display circuit design.The calibration of sensor is completed,and the process of sensor and detection system from scratch is realized.2.The dissolved oxygen sensor adds a platinum silver protective electrode.Compared with the traditional electrochemical dissolved oxygen sensor,the silver electrode,the electrolyte in the electrolyte and the oxygen in the measured water sample are not consumed in the measurement process,which improves the service life of the sensor,reduces the measurement error of the sensor and saves the manpower cost of changing the electrolyte frequently.3.The auxiliary electrode was improved,and a double helix structure auxiliary electrode was proposed.The performance of the double helix structure auxiliary electrode dissolved oxygen sensor and the single helix structure auxiliary electrode dissolved oxygen sensor were compared in terms of sensor stability,response speed,accuracy and linearity.The experimental results show that the double helix auxiliary electrode dissolved oxygen sensor has good stability,fast response,good linearity and small relative error,and its comprehensive performance is obviously better than that of single helix auxiliary electrode dissolved oxygen sensor.4.On the basis of the mechanism analysis of the parameters such as temperature,atmospheric pressure and salinity which affect the detection performance of dissolved oxygen sensor,the compensation of temperature,atmospheric pressure and salinity parameters was corrected by the experiment.Compared with the iodometric method,the measured dissolved oxygen sensor has a relative error of less than 4%,and has high stability and anti-interference ability.