声表面波矿井瓦斯传感技术基础研究

The application of wireless mine gas sensor is limited as traditional gas detection technologies of catalyzing burning gas sensor and infrared gas sensor is difficult to be wireless. So, a new method called surface acoustic wave (SAW) technique is adopted in this research project. Based on the method of combining theoretical analysis, experimental research with Gaussian simulation, the mechanism of SAW gas sensing is studied. Gas sensitive film with good selectivity and adsorption is prepared by carbon nanotubes (CNT) through modified with the transition metal and metal oxide. Depositing CNT film on the sensing area of SAW device, the influence law of gas adsorption on the film by factors of atmosphere pressure, temperature, humidity, etc. is studied using the experiment system under three different conditions of CH4, background gas of CO,H2S added and coal dust added. The key parameters of SAW sensor such as temperature and humidity work scope, range and repeatability are obtained by these experiments. Molecular dynamics of gas absorption and stripping on CNT film is carried out using Gaussian, combined with experiment results, sensing mechanism is revealed. The project has important significance for developing new wireless gas sensor and improving the application of mine Internet of things in gas monitoring.

载体热催化等传统瓦斯检测技术不易于无线化，限制了无线瓦斯传感器的推广应用。项目提出将声表面波技术应用于瓦斯检测，采用理论分析、实验研究和Gaussian模拟相结合的方法开展声表面波瓦斯传感技术基础研究。以碳纳米管为敏感膜材料，筛选对瓦斯具有催化作用的过渡金属及金属氧化物对薄膜修饰，制备常温下对瓦斯具有良好选择性和吸脱附性的敏感膜；在声表面波器件传感区沉积薄膜，以元件输出频率偏移量和阻抗为主要指标，利用实验系统在CH4、添加CO、H2S等背景气、添加粉煤尘三种实验气氛中考察压力、温度、湿度等因素对瓦斯吸附脱附的影响，获取温湿度工作范围、量程、重复性等传感器关键指标；通过对瓦斯吸脱附分子动力学进行Gaussian模拟，结合实验结果，阐明传感机理。项目研究对开发易于集成和无线化的新型瓦斯传感器，推进矿山物联网在瓦斯监测中的应用，具有重要意义。

实现低浓度瓦斯的常温检测有利于克服传统半导体原理和催化燃烧原理的高温工作缺陷，提升传感器的性能和寿命。项目将声表面波技术应用于瓦斯检测条件，开展了探索性研究。利用COMSOL软件仿真，建立了器件的物理模型，开展了延迟线型SAW器件的结构仿真与优化设计，确定了在特征频率为201.51MHz下的金属化率、电极高度比等相关参数，并以模拟参数为参考完成了器件的加工及性能考察；制备了穴番-E、穴番-E-羟基化多壁碳纳米管和聚苯胺-多壁碳纳米管3种敏感膜，以滴涂法实现了材料的负载；以氮气为载气，测定了0~5%CH4浓度下3类传感器的响应特征。研究表明：3种薄膜对甲烷都具有一定的敏感性，且都能呈现出较好的线性关系；响应时间关系为聚苯胺-碳纳米管﹥穴番-E-碳纳米管﹥穴番-E;检测范围为穴番-E-羟基化多壁碳纳米管﹥穴番-E﹥聚苯胺-多壁碳纳米管。该研究为新型声表面波瓦斯传感器研制提供了参考，但背景气体影响和气体选择性还有待进一步研究。