Realization of a room-temperature/self-powered humidity sensor, based on ZnO nanosheets

In this paper, we report the first use of ZnO nanosheet-based direct-current nanogenerators (NG), as a room-temperature self-powered humidity sensor. It has been shown that the networked ZnO nanosheets are structurally stable under external mechanical pressures; hence these 2D nanostructures can be proposed as an emerging/attractive candidate in the field of mechanical energy harvesting. Also, benefiting from the high surface adsorption activity and large surface-to-volume ratio of ZnO nanosheets, we propose the fabricated NG as a promising self-powered gas sensor. Our study demonstrates short circuit and open circuit sensitivities of about 43.4% and -2.96%, because of humidity exposure. It is notable that the achieved output short circuit sensitivity is more than 10 times higher than the maximum sensitivity of a recently reported self-powered humidity sensor, based on ZnO nanorods. High sensitivity and stability, as well as direct-current output current are attractive properties of the realized humidity sensor, which can be proposed as a promising self-powered sensor. (C) 2016 Elsevier B.V. All rights reserved.