Abstract
A monolayer graphene sheets have been prepared via sonochemical approach. Nanocomposites made of graphene doped polysilicon were prepared via mill-roll approach to develop 2D-assembled graphene monolayers aligned parallel in the polysilicon matrices, specifically for ultrasensitive mechanical sensor devices. The developed nanocomposites were characterized via SEM, XRD, FTIR and Raman spectroscopy. It was found that the graphene tended to align parallel in the polysilicon matrices, where Si-H and Si-C bonds between the graphene and polysilicon was formed. Moreover, the increase of graphene contents into the polysilicon matrices instigated a decrease of the amorphous silicon bands and increasing the crystalline Si-C bands. The distance between the aligned graphene layers was strongly dependent on the amount of graphene incorporated in the polysilicon. The mechanical measurements were analyzed based on Ogden and Halpin-Tsai models. These two models indicated that the graphene aligned parallel in the polysilicon matrices and their modulus of elasticity is increased by 10 times at concentration of 0.15 wt%, only. The dissipation energy and linear damage factor were determined under the cyclic stress-strain fatigue. The prepared nanocomposites were examined as mechanical strain sensor. Among all samples, the doping of polysilicon with 0.09 wt% of graphene resulted in a highly sensitive mechanical strain sensor with linear regression up to 22 %. This sample exhibited fast response time of 4-5 s and very fast recovery time around 2-3 s. Therefore, this developed sensor will pave the way to manufacture ultrasensitive mechanical sensor for real daily life use. (C) 2020 Elsevier B.V. All rights reserved.