基于MEMS叠层微结构SO2毒气传感器的研究

针对新型有机半导体电导率偏低的技术难点，提出了一种多孔上电极的叠层微结构，以真空镀膜技术形成气敏膜，采用MEMS微加工制成气体传感器。依据等效电路和工艺边界条件，通过电导公式推导出传感器的输出电导可提高103倍，解决了有机半导体的信号采集问题。通过SEM微观形貌，确认蒸发电流100~120A、蒸发时间8~12s的电极成膜最佳条件；气敏膜表面呈现二次化学反应融合的200nm左右“米粒状” 活性颗粒状态，均匀一致，孔隙有序。测试结果表明：对SO2最佳灵敏度时，比例系数为0.15~0.35硫酸掺杂CuPcxPANI1-x，考虑到减少H2S气体干扰，选择CuPc0.35PANI0.65；加热电压VH为1~2.5V会提高灵敏度特性和响应恢复特性，响应时间30 s；传感器输出特性为单对数线性关系，可实现0~200×10-6之间检测范围；6个月的稳定性考核，输出阻抗漂移≤±5%，灵敏度漂移≤10%。

Study on MEMS Laminated Microstructure Sulfur Dioxide Poison Gas Sensor

Aimed at the technical difficulty of low electric conductivity of new-style organic semiconductor, bring forward a kind of laminated microstructure on porous upper electrode, use the technology of vacuum deposition to form gas sensitive film, and adopt MEMS micro-fabrication to make gas sensor. According as the equivalent circuit and the technology boundary condition, through the conductance formula deduce that the output conductance of the sensor has increased 1000 times, has settled the signal gathering problem of organic semiconductor. Through SEM microcosmic pattern, affirm the best condition, evaporating electric current is 100~120A, and evaporating time is 8~12s. The surface of gas sensitive film is covered with activated granules, which are inosculated in the secondary chemical reaction, like rice grain, about 200nm, symmetrical, uniform and has order holes. The testing result indicates that CuPcxPANI1-x doped with vitriol whose coefficient of proportionality is 0.15~0.35 has the best sensitivity to SO2, considering reducing the interference of H2S, select CuPc0.35PANI0.65; when heating voltage VH is 1~2.5V, sensitivity and responsive restorability will be enhanced, and responsive time is 30 seconds; the output characteristic of sensor is single logarithmic linear relation, and the detecting range is 0~200×10-6; through examination of stability for six months, output impedance is less than or equal to ±5%, sensitivity is less than or equal to 10%.