Research On Micro-nano Gas Sensor For Chlorobenzene Detection

Chlorobenzene,as an intermediate and solvent of many benzene series reactions,has a wide range of applications in chemical,medical and other fields.Chlorobenzene gas is not easy to dissipate in the environment and has high toxicity.It has been listed by the environmental protection agencies as hazardous waste,priority toxic pollutants and carcinogens.Once leaked,it will cause great harm to our lives.In the air,the safe concentration of chlorobenzene gas exposure is 75 ppm.When the gas concentration exceeds 2400 ppm,it will be life-threatening in a short time.Due to its toxicity,it is particularly important to detect chlorobenzene gas in a low concentration environment.The traditional chlorobenzene analysis method is gas chromatography,but this method has a long detection cycle and is expensive,which cannot meet the fast,low-cost,and portable field applications for environmental monitoring.Because micromachines have the advantages of small size,lightweight,stable performance,fast response,and high sensitivity,they can play an important role in chlorobenzene gas sensors.At present,there are still few reports on gas sensors that detect chlorobenzene.This may be due to the relatively stable chemical characteristics of chlorobenzene gas.Traditional gas sensors have a low response and poor selectivity when detecting chlorobenzene.The main work of this thesis is to manufacture a micro-heating platform on micro-machining technology and optimize the pattern of the micro-heater.Testing and performance research of micro-heaters with different morphologies is performed.The application of chlorobenzene sensor and research on its sensitive characteristics.By optimizing the pattern of the miniature heater,the gas sensor can reach a high temperature of 220°C at 30 mW power consumption,which realizes an optimized design of the gas sensor.The COMSOL was used to verify the heating wire at 205°C to 240°C.It was found that the temperature uniformity of the device was good,and the effective area in this temperature range could reach 58%.ZnFe₂O₄ nanoparticles were synthesized by a hydrothermal method and were drip-coated on a MEMS-based microheater to prepare an ultra-sensitive semiconductor metal oxide gas sensor.Studies have shown that the optimal temperature of ZnFe₂O₄ nanoparticles for chlorobenzene gas is 220°C.At the same time,the detection of chlorobenzene gas from 500 ppb to 10 ppm concentration is achieved,and the detection limit of the sensor is 500 ppb.The oxygen ion trap barrier model was used to explain the response mechanism of ZnFe₂O₄ nanoparticles to chlorobenzene gas.ZnO nanomaterials were synthesized by a hydrothermal method and modified on a micro-heater,and a chlorobenzene gas sensor based on ZnO nanomaterials was prepared.Studies have shown that the optimal temperature of ZnO materials in a chlorobenzene atmosphere is 257°C.The LOD of this chlorobenzene gas sensor was found to be 200 ppb by detecting from a trace concentration of 200 ppb of chlorobenzene to 10 ppm chlorobenzene.Based on the principle of oxygen adsorption,the change in resistance of ZnO nanomaterials in contact with chlorobenzene gas was explained.This subject has realized a metal oxide gas sensor with low power consumption,high selectivity,and high response by combining nanomaterials with heaters.Compared with traditional ceramic sensors,this sensor has the advantages of low power consumption requirements,easy integration,and portability.It will provide ideas for the further development of high-performance gas sensors.