Fabrication and characteristics of ZnO nanowires array gas sensor based on microfluidics

In this paper, ZnO nanowires (ZnO NWs) array is prepared based on microfluidic technology. The crystalline structures and morphologies of as-synthesized ZnO NWs are characterized by X-ray diffraction and scanning electron microscopy. The results show that ZnO NWs are high-quality crystalline and c-axis oriented. At the same time, the gas-sensing properties of ZnO NWs are investigated for different gases, such as acetone, methanol and ethanol. The measured results prove that ZnO NWs show a sensitivity of 8.26 at 475 degrees C, and the response and recovery times can reach 9 and 5 s separately, when exposed to 200 ppm (1 ppm = 10(-6)) acetone. Compared with the method of conventional hydrothermal technology, the ZnO NWs based on microfluidic technology show high sensitivity and fast recovery time. Finally, the gas sensing mechanism of ZnO NWs is also discussed from the aspect of gain and lose electron of oxygen molecules on material surface.