SnO_2气敏元件灵敏度及选择性的复阻抗分析

Complex Impedance Analysis for Sensitivity and Selectivity of SnO_2 Gas Sensors

运用复阻抗谱方法，在不同浓度乙醇与汽油气体中，测试SnO2厚膜气敏元件的电抗-频率关系曲线，由电抗的变化来标定元件的灵敏度．与以往的测试采用直流电参量标定灵敏度相比，复阻抗测试不仅提高了元件的灵敏度，而且显著改善了选择性．该结果表明复阻抗测试不仅反映元件在气体吸附或解吸时晶粒间界处晶界电阻的变化，也反映了晶界电容的变化，因而更能体现气敏机制的本质．

The impedance characteristics of thick films gas sensors were investigated by measuring the dependence of the reactance component on frequency in testing gas. Using the variations of reactance with the concentration of gasoline or alcohol gas to define the sensitivity of gas sensors,a new method greatly improving the sensitivity and selectivity of gas sensors compared with the traditional d.c. method was proposed. Such improvements maybe come from that the complex impedance analysis detects not only the change of grain boundary resistance but also the change of grain boundary caparitance with the gas adsorption and/or desorption on the surfaces of sensors.