The Design Of Water Quality Testing Instrument Based On Liquid Drop Analysis Technology

The Fiber-Capacitive Drop Analysis Technology is a recently developed newmethod and new technology to conduct a comprehensive analysis of the liquid.Droplet Analyzer is an analytical instrument which is based on Fiber-Capacitancedroplet analysis technique to achieve liquid identification. The issue is to achievewater quality quantitative detection based on this droplet analysis technology with thecombination of water quality indicators detection principle.The water quality being good or bad is closely related to the ecologicalenvironment. Its importance is self-evident to detect the quality of the water and thencontrol the protection of water resource and environment. There are a lot of indicatorscharacterized water quality being good or bad, including dissolved oxygen, salinity,pH, temperature, trace heavy metal elements content. They are all importantindicators, especially in the health of aquatic breeding. Precise control of theseparameters is the key of healthy farming. If we can measure the water qualityindicators accurately and real-time, we can take some appropriate remedialmeasurement according to the results of the parameters, which can greatly improvethe survival rate of fish and shrimp and reduce farming costs, tremendouslyimproving efficiency. Based on this, the paper researches the quantitative detection ofthese water quality indicators-dissolved oxygen, salinity, pH value. Design waterquality analyzing instrument combined with droplet analytical techniques.This topic is a sub-project proposed for the National12th Five-Year Plan of theOcean Development Institute, whose ultimate goal is to achieve the seawatercomposition analysis detection. Combined with the actual project of the droplets onthe basis of laboratory analysis, we focus our research on water quality of the threeparameters-dissolved oxygen, salinity, pH indicators.This thesis is mainly completed the following work:（1） Improve the design of mechanical structure of the existingdroplets analyzer. Major changes happened on the support structure becauseof the extra dissolved oxygen probe. Use the free and easy removal of thepin structure instead of the welding connection, enhancing reliability andstability. （2） Design a three-layer shielding sleeve structure for the annularplate capacitive sensor in order to reduce the stray capacitance, distributedcapacitance, etc.（3） Improve the capacitance signal detection circuit with the newcapacitance measurement program.（4） Complete a digital circuit design with the microcontrollerC8050F021CPU, realizing the data measurement, data displaying, datasaving, which enhances the human-computer interaction.