一种基于氢氧反应热的催化氧气传感器

A Catalytic Oxygen Sensor Based on the Hydrogen-Oxygen Reaction Heat

基于对氢氧反应热的测量 ,设计了1种测量气体中微量氧气含量的传感器 ,它由嵌入反应池的微型薄膜铂电阻 ,氧化锰 -钯催化剂构成 ,铂电阻构成惠斯顿电桥 ;在催化剂作用下 ,氢氧反应放热使反应池内温度升高 ,引起铂电阻值变化 ,使电桥偏移产生响应信号 ;采用直通全消耗微反应池 ,待测氧气可被完全利用 ,使用参比池和恒温装置减小环境温度和湿度波动影响 ;设计的传感器对1～1200×10 -6(w)的氧气呈线性响应 ,定量下限为1×10-6(w) ,90%信号响应时间小于5s;该传感器具有结构简单、响应迅速、灵敏度高、稳定性好等特点。

A newtype of catalytic oxygen sensor has been constructed,based on the measurement of the heat of the hydrogen-oxygen reaction.The sensor,consisting of thin-film Pt thermal sensing resistors and the MnOx/Pd catalyst,was incorporated into a reaction cell and constituted a Wheatstone bridge cirˉcuit together with a reference cell and counter resistors in an isothermal oven.The reaction heat liberated in the hydrogen-oxygen reaction increased the resistance ofthe Ptresistor in the reaction cell,so the resisˉtance deviation in the bridge produced an output signal.Since the gas mixture flows directly through the reaction cell,the oxygen in the mixture can be completely depleted in the micro reaction cell.Thus,the micro cell has a high utilization efficiency of oxygen to be detected.Parameters that affect the detection sensitivityof oxygen,such as reaction temperature,oxygen flowrate,amount of hydrogen,and bridge voltˉage,were investigated.The reference cell and the isothermal oven were employed to reduce the impacts of environmental temperature and humidity fluctuations.The sensor shows a good linear relationship with oxyˉgen concentration in the range of1～1200×10 -6 (w).The detection limit is1×10 -6 (w).The90%response time of the sensor is less than5seconds.The developed sensor has the advantages of simple structure,fast response speed,excellent signal stability and high sensitivity.