▎ 摘　　要

In this work, we present an approach to use graphene oxide-silicon bi-layer flexible structure as stress-based humidity sensors. By the spin-coating method, graphene oxide thin films were deposited onto silicon microbridge as a humidity sensing layer. Upon expose to humid environment, graphene oxide thin films swells and leads to the bending of silicon membrane. Then, the full piezoresistive Wheatstone-bridge embedded in silicon microbridge was used to transform the deformation into a measurable output voltage. The humidity sensing properties of the bi-layer flexible structure, such as sensitivity, repeatability, humidity hysteresis, response and recovery, were investigated in the wide relative humidity range of 10-98%. The test results show that graphene oxide-silicon bi-layer flexible structure exhibits high humidity sensitivity, good repeatability, small humidity hysteresis and clear and fast response-recovery. Moreover, the dependence of the thin films thickness of graphene oxide on the response properties was also examined. At last, the humidity sensing mechanism of the proposed bi-layer structure was discussed in detail. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.