In this work, we analyse the effect of mechanical stresses on graphene devices for application in flexible electronics. The possible Schottky contacts in the transistor are modeled through suitable transmission coefficients describing the tunnelling through the electrostatic potential along the graphene channel. The surface potential is determined by imposing an equality between the charges computed with a micro-and a macro-model. All these computation tools are explicitly dependent on the choice of geometrical parameters, thus allowing the description of uniform geometrical deformations due to strains along a given direction. Numerical results are computed and discussed.