Research On PH Wireless Sensor And Multi-channel Cloud Monitoring System

With the rapid development of Internet of Things,instrument technology combined with cloud technology is developing in the direction of informatization,intelligence and efficiency.pH is an important index to measure the hydrogen ion activity of solution.Accurate detection of pH is of great significance for the regulation of pH of reaction solution in chemical production and the monitoring of water pollution in environmental protection.Because the traditional pH monitoring instrument adopts single point measurement and wired data transmission,the pH sensor has some disadvantages in complex environment,such as difficult installation and maintenance,corrosion and interference of the line,isolation of each monitoring point.Aiming at the problems of traditional pH monitoring instruments,this paper studies a low-cost pH measurement sensor with the integration of temperature compensation and wireless data communication,and uses the Internet of things technology to build a multi-sensor network to realize multi-channel pH cloud monitoring system to improve the monitoring efficiency.The details are as follows:(1)According to the measurement principle of hydrogen ion selective electrode,the effects of solution temperature,electrode manufacturing error and electrode aging on pH measurement accuracy are analyzed,and the corresponding temperature compensation and electrode calibration methods are proposed.Combined with ZigBee wireless communication technology,the design scheme of pH wireless sensor is proposed;The overall structure of the multi-channel pH cloud monitoring system including four parts,namely,on-site environmental sensors,local monitoring center,cloud platform server and remote mobile monitoring terminal,is determined.(2)The hardware circuit and corresponding embedded program of pH wireless sensor and ZigBee network node are designed;The monitoring host computer is designed by Lab VIEW to realize the on-line monitoring of multi-point pH value and the unified management of sensors.Combined with MATLAB,the cloud map display function of pH value and temperature distribution in the monitoring domain is developed.(3)Deploy the My SQL database on the cloud platform to receive and store the real-time monitoring data uploaded by the upper computer,then design the web server and deploy it to the Tomcat server on the cloud platform to respond to the data request from the client,and finally develop the Android mobile monitoring client to remotely access the cloud server through HTTP connection technology to realize the functions of real-time display of monitoring data,historical curve drawing and exception notification to complete the construction of the multi-channel pH cloud monitoring system.(4)The experimental platform is built to test the system function.The experimental results show that the pH measurement error of the pH detection wireless sensor after temperature compensation can be controlled within ± 0.04 pH,which is reduced by 0.23 pH compared with the measurement error without temperature compensation.The communication between each part of the cloud monitoring system is running properly and the system runs stably,which proves the feasibility of this research scheme.