基于红外热效应的电容式气体传感器研究

Study of capacitive gas sensor based on infrared thermal effect

提出了一种利用气体吸收红外并产生热效应现象检测气体的方法,设计并制造了一种红外电容式气体传感器。该气体传感器采用在密封气室中密封纯净的被测气体,利用被测气体吸收红外的热效应并由此产生压力变化,该压力变化转换为弹性应变膜的应变致使平板电容器的电容变化,由于环境中被测气体与密封气室中被测气体对红外的差分吸收,使得电容的变化量与环境中被测气体的体积分数相关。对甲烷气体的实验结果表明:其检测下限为100×10-6,分辨率为50×10-6。

A way of gas detection on the basis of gas infrared absorption which produces thermal effects is presented.A kind of infrared capacitive gas sensors have been designed and manufactured.The gas sensor seals pure test gas in sealed chamber.Pure test gas absorbs infrare producing thermal effects which leads to pressure change.This pressure change transform into elastic film strain resulting in capacitance variation.As a result of difference absorption of infrared between seals pure test gas in sealed chamber and mixed test gas in environment,the capacitance variation express test gas concentration change in environment.The experimental result show that methane detection lower limit is 100×10-6 while its resolution can reach 50×10-6.