MEMS热导甲烷传感器设计与研究

Design and Research of MEMS Thermal Conductivity Methane Sensor

热导气体传感器在煤矿井下检测高浓甲烷方面有着重要应用。为了解决传统热导气体传感器在功耗以及灵敏度等方面的不足,开发了一种新型MEMS热导甲烷传感器。利用MEMS工艺在硅基底上沉积Pt电阻薄膜作为敏感元件,同时深刻蚀出微型热导池。建立MEMS热导元件热平衡模型,利用COMSOL软件进行热传导和热辐射仿真,分析热传递情况。基于恒温检测方法,对MEMS热导元件进行应用电路开发,设计恒温电路、测温电路、采样电路等。分析环境温度对传感器造成的信号漂移影响,建立温度补偿算法模型。在温湿度箱中标定新设计的热导甲烷传感器,通过拟合曲线得到浓度计算系数和温度补偿系数。经过试验测试表明,该热导甲烷传感器在4%~100%量程范围内测量误差可以达到真值的±10%。

Thermal conductivity gas sensors have important applications in detecting high concentration methane underground in coal mines.In order to address the shortcomings of traditional thermal conductivity gas sensors in terms of power consumption and sensitivity,a new MEMS thermal conductivity methane sensor was developed.Using MEMS technology to deposit Pt resistive thin films on silicon substrates as sensitive components,while deeply etching out micro-thermal conductivity pools.A thermal equilibrium model for MEMS thermal conductive components was established,COMSOL software was used to simulate thermal conduction and radiation,and the heat transfer situation was analyzed.Based on the constant temperature detection method,application circuits for MEMS thermal conductivity components were developed,constant temperature circuits,temperature measurement circuits,sampling circuits,etc were designed.The impact of environmental temperature on sensor signal drift was analyzed and a temperature compensation algorithm model was established.The newly designed thermal conductivity methane sensor was calibrated in the temperature and humidity chamber,and the concentration calculation coefficient and temperature compensation coefficient were obtained by fitting the curve.Experimental tests showed that the thermal conductivity methane sensor could achieve a measurement error of±10%of the true value within the range of 4%to 100%.