Design And Study On Electrochemical Gas Sensor Characteristics Test System Based On Virtual Instrument Technique

Nowadays, gas sensor technology develops quickly and becomes more widely available. As one of the branches, electrochemical gas sensor is also widely applied. But on the aspect of precise measurement of gas concentration, there are two main problems. One is cross-sensitivity, the other is characteristic drift of gas sensor. These problems have puzzled people for a long time, particularly on a long-term on-line gas monitoring. This paper focuses on the sub-item of the supervisor's research project (develop a comprehensive environmental parameters monitoring system tor a power company), and develops a comprehensive test system for electrochemical gas sensor performance parameters. Therefore the best point of gas sensor can be available so as to provide a basis for the amendments compensation of measurement error caused by cross-sensitivity and characteristic drift.Taking into account the actual testing requirements, the author presented an overall scheme testing electrochemical gas sensors system, which is mainly made up of the enhanced 51 MCU and PC based on the virtual instrument technique. Moreover, the corresponding experimental verification for the designed system is also given by means of the fixed electric potential electroanalysis sulfur dioxide sensor. Slave computer is divided into the design of hardware and software parts, including the choice of chip for slave computer, the choice and implementation of communications port, the configuration of slave computer analog ports, the realization of data acquisition and the design of communication software. The program of PC realized the design of the instrument interface and the compilation of functional modules software primarily by virtue of virtual instrument technique. These modules include the serial communication design, channel parameters configuration, zero shift measurement, linear correlation measurement, temperature drift measurement , cross-sensitivity measurement, response / recovery time measurement, data storage, and the report program generator.It can be educed from the measurement of various characteristic parameters of the fixed electric potential electroanalysis sulfur dioxide sensor that the best operating temperature of the sensor is about 20℃, the zero shift takes up±2.3% of the full scale. When the gas concentration is less than 72.3 ppm, the linearly dependent coefficient is 0.993; response time is 15 s; and recovery time is 19 s. As for cross-sensitivity, the author separately measured CO, H₂S, and NO with the concentration of 100 ppm, the sensor output values are 0.227 V, 0.233 V, and 0.208V in sequence. From the experimental results, it can be seen that the integrity of the various parameters and curves of the gas sensor can be measured with this system, and it can provide a reliable basis for further study and application.