Research On The Application Of Wearable Gas Sensors And Their Array In Industrial Safety

With the acceleration of industrialization,industrial safety has become an undeniable issue in the industrial production process.In the course of industrial production,encompassing various stages such as raw material manufacturing,processing procedures,emission of deleterious gases,and product packaging,the consequential release of toxic and hazardous gases poses a significant peril to the occupational health of workers.Therefore,real-time monitoring of toxic and harmful gases in the production environment is crucial for industrial safety and control.However,traditional gas sensors often adopt a fixed installation approach,which cannot provide real-time detection of the actual environment surrounding workers.On the contrary,wearable gas sensors,leveraging their portability and ability to operate at room temperature,have gradually emerged as ideal monitoring devices in the field of industrial environmental safety.This research focuses on the application requirements of wearable gas sensors in the industrial safety field.It selects conductive polymers and graphene-based materials as the main sensitive materials and develops high-performance sensor units through structural design and surface modification of the sensitive materials.Subsequently,multiple sensor units are integrated into a sensor array.Additionally,machine learning algorithms are employed to achieve component identification and concentration analysis of complex industrial environments and harmful mixed gases（NO₂ and NH₃）within a wide humidity range.Based on this foundation,a wearable detection device and intelligent terminal application based on Bluetooth 5.2 are further designed to achieve real-time monitoring and early warning of hazardous gases in workers’working environments.The main research objectives are as follows:（1）Preparation of a flexible NH₃ sensor based on Sb-doped SnO₂/polypyrrole:Polypyrrole（PPy）was selected as the main sensitive material to fabricate a flexible room temperature NH₃ sensor based on Sb-doped SnO₂/PPycomposites through material structure modulation and heterojunction formation.The sensor based on 3 at%Sb-doped 10 mol%SnO₂/PPycomposite material（PyS3）exhibited the highest sensitivity（with a response of 213%to 100 ppm NH₃,approximately three times that of pure PPy）.Due to the abundant electron density in Sb-doped SnO₂,the formation of heterojunction widened the depletion layer on the PPyside,resulting in a significant increase in resistance and thus enhancing the sensitivity of the sensor.The nanowires of PPysynthesized via a soft template method were coated on the surface of antimony-doped tin dioxide nanospheres,forming an interlaced network structure that facilitates gas diffusion.This network structure demonstrated better mechanical properties compared to particulate PPy.The PyS3 sensor exhibited excellent resistance to bending,with a sensitivity decrease of only 2.6%to 10 ppm NH₃ after 100 bending cycles compared to its initial state.Its outstanding flexibility makes it a potential candidate for wearable NH₃ sensors.However,the sensitivity of the sensor is significantly affected by humidity,and reducing humidity interference is a crucial issue that must be addressed for practical applications.（2）Development of a wearable NH₃ detection wristband and mitigation of humidity cross-sensitivity:To further enhance the sensitivity of the sensor to NH₃,polyaniline（PANI）with a unique proton-conducting sensitive mechanism was chosen as the main material.Through doping and composite methods for sensitivity enhancement,a wearable NH₃ sensor based on Sb-doped SnO₂/PANI composite material was developed.Gas sensitivity tests revealed that the sensor based on 3 at%Sb-doped 20 mol%SnO₂/PANI mesh composite material（PS3）exhibited the highest sensitivity（with a response of 33.1 to 100 ppm NH₃ at 70%relative humidity）and a low detection limit（500 ppb）.These results demonstrated that PANI has advantages over PPyin NH₃ detection.Furthermore,the sensor based on Sb-doped SnO₂/PANI composite material exhibited excellent selectivity,long-term stability,and mechanical robustness.The improved sensitivity of the sensor,compared to pure polyaniline-based sensors,was attributed to the increased resistance effect of donor Sb-doped SnO₂ on the sensitive material.By appropriately partitioning humidity levels,regression prediction equations were developed to mitigate the interference of humidity on NH₃ detection by the sensor.Based on these findings,high-performance sensors and flexible functionalized circuit modules were integrated into a silicone wristband,creating a small-sized,low-power,wireless wearable NH₃ sensing device.This device formed a sensing-transmission-display chain with an intelligent display terminal.The terminal program included regression equations for NH₃ concentration under different humidity conditions,enabling analysis and prediction of NH₃concentration within a wide humidity range（20%to 80%RH）.（3）Research on wearable gas sensor array for identification and detection of hazardous mixed gases in mines:Addressing the demand for identification and detection of hazardous mixed gases（NH₃,NO₂）in industrial environments and advancing the application of wearable gas sensors in complex industrial settings,we integrated our developed NH₃ sensor based on Sb-doped SnO₂/PANI composite material with RGO/WO₃ as the NO₂ sensitive material.This integration resulted in a wearable sensor array capable of component identification and concentration analysis of NH₃ and NO₂ mixed gases.The sensor array was tested with varying concentrations of NH₃ and NO₂ single/mixed gases,and a dataset of gas concentration and sensor responses was established.Reverse neural network algorithms and least squares regression analysis were employed,and the model was trained using the dataset.The results demonstrated an accuracy of 100%in gas identification and theoretical prediction levels exceeding 99.0%for concentration.Building upon these results,we employed the same strategy as the previous chapter to mitigate the influence of humidity on the sensor array.Furthermore,we analyzed the impact of other factors present in complex industrial environments,such as interfering gases,stress,temperature,and flow rate,on gas detection results,to comprehensively evaluate the performance stability of the sensor array.Finally,we developed a wireless wearable device for toxic gas detection in mines and incorporated gas classification and identification algorithms for different humidity ranges into an intelligent application terminal.This implementation enabled component identification and concentration analysis of NH₃ and NO₂ mixed gases in complex mine environments.The synergistic approach of wearable sensor arrays and machine learning algorithms provides an expedient and efficacious method for achieving high precision in the identification and detection of hazardous gas mixtures within the context of mine safety.