Small variations in the sheet resistance of graphene layers with compressive and tensile bending

We synthesized graphene on copper foil by chemical vapor deposition using H2 and CH4 gases, followed by transferring the synthesized graphene onto various substrates. Controlling the number of layers was achieved through the variation of transfer times, and the variations of sheet resistance and transmittance with the number of layers were measured. We also investigated the variation of resistance with the radius of curvature of graphene film. As the radius decreased, the resistance increased with tensile bending and decreased with compressive bending. However, the degree of changing resistance is small enough to be applicable into flexible devices. The resistance of monolayer graphene was found to be varied in the range of as small as ±3% by the tensile or compressive bending. It was further found that although the degree of changing resistance gets larger with increasing number of graphene, the tensile bending increased the resistance by less than 20% even in case of four layer graphene.