Research And Development Of Indium Oxid-based Gas Sensor And Its Performance Research And Remote Monitoring Experiment

Metal oxide semiconductor gas sensors play an important role in remote monitoring of low-concentration volatile organic gases,and are widely used in environmental protection,medical treatment,industrial production and other fields.In₂O₃ based gas sensors have great development space due to their high conductivity,high response,high activity,high performance and other characteristics among many metal oxide semiconductor gas sensors.It is difficult to meet the practical application owning to the lack of selectivity and high response temperature for pure In₂O₃ sensors.In order to improve the response of In₂O₃-based sensor and achieve the goal of remote monitoring,the paper starts from the aspect of optimizing the sensitive layer of gas sensor to optimize the performance of In₂O₃-based gas sensors by doping Zn and Sn ions.Taking the remote monitoring of low-concentration ethanol gas as an example,the main contents of the gas monitoring system are as follows:(1)A series of Zn/In₂O₃ sensing layer materials doped with different proportion of Zn2+ and adding different volume of NaOH solution were prepared by calcination using ethanol and glycerol as solvents.Various characterization results show that the addition volume of NaOH solution and the doping amount of Zn2+ in In₂O₃ system are closely related to the morphology and crystal phase of Zn/In₂O₃,which leads to the different gas sensitivity properties of Zn/In₂O₃ compounds to ethanol.Gas sensitive test results show that the sample of Zn/In₂O₃(1/1)prepared by adding 10 ml NaOH solution exhibites the best response in high humidity environment,and its response value to 50 ppm ethanol remains around 200 at the temperature of 220?,which is about 10 times higher than the corresponding response values of pure ZnO or pure In₂O₃ gas sensors and consistent with the results of Oabs by XPS test content.At the same time,the Zn/In₂O₃ sensors demonstrate good stability and selectivity in high humidity environments.(2)The porous In₂O₃ nanoribbon sensitive layer was prepared by solvothermal method,and the specific surface area of In₂O₃ nanoribbon was controlled by changing the addition amount of CTAB to optimize the performance of In₂O₃ sensor.The response value of In₂O₃ with 0.1g CTAB to 50 ppm formaldehyde at 180? is 26.8,and its response value is nearly 5 times higher than that of In₂O₃ without CTAB added.(3)Sn particles were introduced into the broken In₂O₃ nanorods to prepare Sn/In₂O₃ sensitive layers of different thickness,and the SEM analysis shows that the introduction of Sn4+ makes the Sn/In₂O₃ nanorods transform from the cracking state to the non-uniform and uniform broken state.Among them,The Sn/In₂O₃ sensor doped with 5%Sn has the best sensitivity,and the response value of Sn/In₂O₃ is about 28 at 220 ? to 50 ppm ethanol,as well as they are characterized by rapid response and good stability.(4)A process of on-line monitoring of low concentration ethanol gas is completed combining with the intelligent cloud platform and Zn/In₂O₃(1/1)sensor.In order to realize data management,using STM32F103RBT6 as the core data processing module and Zn/In₂O₃(1/1)sensor as the component.The ethanol data detected by Zn/In₂O₃(1/1)sensor transmits the cloud platform of tact cloud through WiFi communication module,so as to realize real-time data management.In this paper,the method of preparing the sensitive layer is an important step towards the direction of making the ultra-sensitive sensor,and the test results of the Zn/In₂O₃(1/1)sensor monitoring system show that the gas monitoring system has a certain application value in realizing the remote monitoring of the concentration of ethanol gas.