We design and realize two nano-structured surfaces that support graphene plasmon modes for sensing applications in the mid-infrared range. More specifically the two designs are engineered on a CaF2, IR-transparent, substrate which allow backlight illumination, which is suitable for biosensing in aqueous medium. The nano-structured surfaces have the objective to combine thin metal structures with a graphene layer to engineer graphene plasmon modes generation at wavelengths difficult to obtain in single graphene structures. The designs are first modeled with Finite Element Method Analisys (FEM), using COMSOL, and then fabricated and tested.