Wireless LC Gas Sensor Based On Polyaniline/carbon Nanotube Composite Sensitive Material

With the development of industrial production,the problem of environmental pollution becomes more and more serious.How to realize the rapid and accurate detection of harmful gases is very urgent.The gas sensor of the research group is used as the sensitive material with semiconductor materials,which has many advantages of short response recovery time and high sensitivity.Prophase research there are still some limitations,however,are all active device and high working temperature,for example,in circumstances such as gas airtight pipeline detection of specific gases can't use this kind of sensor is limited by a lot of application field.In view of the limitation of the active sensor,this paper proposes a principle with LC mutual inductance coupling of wireless passive gas sensor,and utilization of high stability,can work at room temperature of polyaniline/carbon nanotube as the sensor of gas sensitive material,the preparation by the method of reasonable wireless passive gas sensor,realized the non-contact temperature sensor test.The main research contents are as follows:The properties of the gas-sensitive materials have been studied.The carbon nanotubes are acidified by mixed acid solution and characterized by scanning electron microscope?SEM?.The experimental results show that the acidified carbon nanotubes have more gaps,which enhance the adsorption ability of the gas and other gas-sensing materials,and Polyaniline was synthesized by polymerization of aminobenzene monomer on the surface of carbon nanotubes,thus forming the sensitive material of polyaniline/carbon nanotubes.Two kinds of wireless passive gas sensors are designed.The two structures are simulated respectively using ADS simulation software,and parameters in a reasonable range are obtained.Through the analysis of different preparation processes,the final decision is made to transfer the lead-free aluminum paste to the alumina ceramic substrate by a screen printing process,and a wireless passive gas sensor was prepared by applying the gas sensitive material to the basic structure.The first is a wireless passive gas sensor with a spiral inductor structure,and the second is a wireless passive gas sensor consisting of acircle of inductors and interdigital electrodes.An experimental platform was built to test the performance of the sensor.After testing,In an atmosphere of 300ppm for NH₃,the sensitivity of the spiral inductor wireless passive gas sensor is approximately 0.015 MHz/ppm;The sensitivity of the cross-finger capacitive wireless passive gas sensor is about 0.04 MHz/ppm.In contrast,the cross-finger capacitivewireless passive gas sensor is more sensitive than a spiral inductor wireless passive gas sensor,and can detect up to 50ppm of NH₃ gas.