The Research On The Gas Sensor Based On Core-shell NiO@ZnO One-dimensional Nanotube

With the rapid development of the social economic, the problem of air pollution is comingtoo, so the detection of toxic gas and harmful gas has become a urgent issue. This is also themain reason why the gas sensor developed so fast in our country in recent years. Among all thetoxic and harmful gas, H2S has been a great threaten for the health and life of the people, so if wecan detect the concentration of the H2S gas, it will have a significant meaning for human being.Based on the understanding the working mechanism of the semiconductor gas sensor, weembarked on our work from two aspects: one is sensitive material, another is the circuit design,in order to acquire the prefect gas sensing property. Firstly, in the aspect of sensing material, wefabricated the composite one-dimensional nanotubes of NiO@ZnO with core-shell structure. Forthe huge ratio of surface to volume and perfect electrical character, it provided a great possibilityfor a good sensing performance. Following we characterized this composite material basically toconfirm the structure. The testing results indicate that the gas sensors we made have highsensitivity, short response and recovery time, as well as anti-jamming ability. Next, For thedesign of the following circuit, we employed Wheatstone bridge to detect the weak change, andenlarged the weak information by instrument amplifier INA128. Instrument amplifier INA128has a lot of advantages, such as high common-mode rejection and input impedance, low noise,low linearity error, low offset voltage, low input current and so on. AVR controller Mega16weused is the main control chip, in order to improve the reliability, increase the function, reduce thepower consumption and low cost. The gas sensor we designed can test H₂S gas in the range of0.001%（10ppm）-0.02%（200ppm）. The resolution can reach0.001%（10ppm）, and theresponse time can be reduced to5seconds. Also, this gas sensor has the function of alarm, therange of which is from0.001%to99.9%, and we can set to any value among this range.