▎ 摘　　要

The use of graphene for strain sensors has attracted enormous attention due to its prominent mechanical and electrical properties. In this paper, we report on the preparation and characterization of a novel type of strain sensor based on graphene composite films with layered configuration. Highly reliable and sensitive composite films strain sensors based on graphene were produced from solution processed graphene flakes by spray coating method. The layered strain sensor which could sustain a large tensile deformation (25% strain) demonstrated high sensitivity to mechanical strain with gauge factors of 6-35. And the sensitivity of this type of strain sensors can be tuned over a relatively wide range of values by adjusting the deposition parameters. What's more, the layered composite films are more durable compared with the fragile pure graphene films. In addition the main mechanisms are investigated, resulting in theoretical models which predict very well the observed behavior. (c) 2015 Elsevier Ltd. All rights reserved.