Development Of Online Monitoring PH System Based On A Microfluidic Chip

The measurement of pH is of great importance in the fields of modern industry,agriculture,biological engineering,and environmental science,especially about the demand for industrial wastewater along with extreme situation.However,most of pH sensors work by means of sampling,and the real-time monitoring of industrial wastewater with changes cannot be conducted,so that it is difficult to control the damage caused by the pollution at the first time.Microfluidic system is composed of a network of micro-channels and the controllable fluid runs through the whole system.So microfluidic system can meet the need of monitoring the fluid of pipe in real-time.Under the backgrounds,a pH-sensing PDMS microfluidic chip system which can detect the pH changes of industrial wastewater in real-time is set up.The main contents of this thesis include followings:A pH-sensing substrate is fabricated.Covalent bonding method is selected to achieve pH sensitive membrane.Preparation methods of pH-sensing membrane and reaction mechanism are studied.Furthermore,optimal proportion to get good pH sensitive membrane is determined the optimal experiment scheme and parameters,and the sensing properties of pH-sensing substrate is tested.A pH-sensing microfluidic chip is fabricated.According to the detection method,the micro-channel pattern was designed,and a cover with a channel made by casting PDMS onto the male mold is bonded to the pH-sensing substrate in order to get a pH-sensing microfluidic chip.The sensing properties of this pH-sensing microfluidic chip is tested.The pH-sensing microfluidic system is set up and tested.LabVIEW,WaveForms and Matlab software are used for data reading,BP neural network training and application.The whole system can realize online real-time monitoring of solution pH.