Design Of Array Type Dissolved Oxygen Sensor

Dissolved oxygen refers to molecular oxygen in the air dissolved in water and it is usually represented by DO. The oxygen concentration in water is an important indicator of water quality, and it is also an important factor of water purification. When the water is contaminated and the concentration of oxygen is low, most fish and varieties of plankton can not survive, anaerobic bacteria in the water will breed quickly, organic will make water deteriorate and stink because of corruption, this is the basis of evaluating agricultural, industrial and fishery water. Therefore, how to monitor the oxygen concentration in water by effective and efficient methods is of utmost importance.The thesis presents a design of array type dissolved oxygen sensor which is based on electrochemical probe method. The sensor system consists of multiple sensor probes, signal acquisition circuit, temperature compensation algorithm, embedded system and master computer. Using array structure can correct single probe's error which is caused by the aging of oxygen permeable membrane and electrode. The system uses STM32 as the main control chip and PT100 as temperature measurement element, it combines the analog-to-digital conversion chip AD7794 to realize high precision measurement and uses the LM algorithm as temperature compensation algorithm of the sensor. Data collected by the system can not only through the VFD screen display, but also through the serial port to send to the master computer which is programmed by LabVIEW or the embedded terminal that run the Qt/Embedded program to display the data waveform, storage data.The experiment results indicate that the temperature in the range of 0? ?40?,temperature drift can be suppressed effectively, the error caused by the aging of the sensor has been solved very well. The precision of the sensor is 0.35mg/L, and it meets the requirement of monitoring the oxygen concentration in water of industries such as aquaculture and environmental detection.