The Development Of Temperature Automatically Controlled Gas Sensing Materials Test System

With the development of science,the advent of Internet of Things and the era of artificial intelligence,the gas sensor in life is more and more comprehensive and accurate.In order to take full advantage of the shape,pattern and structure of gassensing materials and further improve the sensitivity of semiconductor gas sensor,our research group apply National Natural Science Foundation of China(Study on the Fabrication and Gas Sensing Properties of Porous P-N Heterostructure with Three Dimensional Network Foam Nickel No.61474056).Due to the fact that the traditional test system can't test the gas-sensing materials based on the foam nickel,we design a novel type of gas-sensing test system,and fast measuring method for a large range of resistance The system not only can test and protect the gas-sensing materials based on porous materials,but also can test the powder or thin film gas-sensing materials.At the same time,the temperature can be accurately measured and presents a stairs type to rise,so that the operation of the material testing process is more intelligent.The test system consists of three parts: testing environment,hardware circuit and PC software.The testing environment mainly includes the manufacture of gas tank,the customization of test probes and the establishment of test bench.The purpose of protecting the structure of the porous materials is achieved by using small elastic probes and a micromatic setting.The hardware circuit is based on embedded processor—ARM7,which is mainly divided into resistance measurement module,temperature measurement module and heating module.The working temperature of the gas-sensing materials should be precisely measured.Under this condition,a temperature measurement module is employed in the system,aimed at detecting the temperature of gas-sensing materials.In order to measure resistance rapidly,the method of measuring range of resistance overlapping is employed in the resistance measurement module,making it suitable for the testing of gas-sensing materials with the sensitivity of 10000 or less.The heating module consists of an integrated DA converter in the microcontroller and an external power amplifier,forming the numerical control voltage source.Combined with the PID control algorithm,the temperature of the heating device can be increased step by step.In this paper,we study the testing process of gas-sensing materials.By using the PyQt software to create the interface of the PC soft,the operation of the test process becomes more intelligent.The system program can be divided into two working modes: the working mode One and the working mode Two.The working mode One is suitable for seeking the best working temperature of gas-sensing materials.Temperature can be raised up step wisely without manual operation.The working mode Two is suitable for response-recovery characteristics test of gas sensing materials.During the test,the reference resistance is not changed to make the measuring procedure faster.These working modes can greatly save human resources.This test system can test and protect the gas-sensing materials based on porous materials.By using the method of measuring range of resistance overlapping,the measuring range is 1-500 M ohm,and the error rate is below 2%.Even the resistance value is above 10 M ohm,the measuring speed can reach 10 times per second.Temperature control becomes fast and accurate by using a combination of conventional PID control and fuzzy PID control.The measuring range of temperature is 0-500?,and the error rate is below 1%.The test system provides a reliable significative and testing method for the development of new type of gas-sensing materials.