Preparation And Stability Of ZnO-based Gas Sensor Arrays

Gas sensor arrays were fabricated though screen-print technique. Arrays consist of RuO2 heater, Ag heating electrode, Au measurement electrode and 4 ZnO-based sensitive units based on Al2O3 ceramic substrate. The sensing films were treated by dipping into the concentration of 1mol/L,3mol/L,5mol/L,8mol/L copper acetate and zinc acetate(1:1 molar ratio) solution respectively, sintered at 650℃for 2h. Some important characteristics of the integrated sensor arrays, such as the heating properties, the temperature-resistance properties and the sensitivity were investigated. Peculiarly, the effect on the sensor arrays sensitivity and stability by the sensing films microstructure and CuO(P)-ZnO(n) heterojunction was studied. Analysed the consistency of gas sensor arrays.The preparation of sensor arrays by screen-print technique has some good characteristics. Such as the heating properties, the power consumption is only 450mW. the equipment and technology is simple, Preparation method is flexible and has good control ability and re-productivity. Sensor arrays have reliable properties. The microstructure of the pure ZnO and dipped sensing film after sintered 650℃for 2h were analysed by SEM. The result showed: pure ZnO sensing film has Porous, osteoporosis structure and the grain size is larger. The structure of dipped sensing film is compact and the grain is smaller than pure ZnO. Since the addition of Cu+ can effectively inhibit grain growth in the sintering process.Compared with the stability of pro-treated and post-treated gas sensor arrays, and the mechanism was analysed.The short-term stability was tested under 400℃,100ppm alcohol condition. The air resistance of all sensor arrays decreased with testing time increased at the beginning of the test, then become stable gradually. The sensitivity of pure ZnO array has a large range change during the whole testing, while the dipped arrays are relatively stable. The long-term stability and effect of air humidity were tested. The result indicated: the air resistance of pure ZnO array has apparently fluctuating, the relative error of air resistanceεR(>25%) accounted for 20% of total test, the phenomenon of signal excursion was found. The dipped arrays have good stability,εR(>25%) accounted for 10%,5%,5%,3.3% of total test, respective. It is the microstructure of sensing film and CuO(P)-ZnO(n) heterojunction that affect the stability of arrays.The improvement of preparation technology is the key way to improve the consistency of the sensor arrays.