Fabricating ZnO nanowires-based humidity sensor via dielectrophoresis method

In this study, ZnO nanowires based humidity sensors were manipulated by dielectrophoresis (DEP) method. ZnO nanowires were grown by hydrothermal method at low temperature (95°C) for 3-24 hr. From the manipulation, we can know that electrical field and vaporization rate of suspension solution will affect the alignment of ZnO nanowires seriously. In the humidity sensor test, the sensor´s resistance increases with increasing RH% level. It showed very high sensitivity, which can reach 450% when the RH% is 100%. The response at 0%-30% and 50%-100% RH% is almost linear. However, a strange observation is that, after increasing the RH% in steps to 100%, when decrease the RH% in steps to 0%. The dynamic response of the resistance to RH% change between extra dry air and saturated air is shown that the sensor can reach 90% of the total change in seconds.