To make the flexible device for objects with complex surfaces, the transparent conductive electrode, porous nylon film, and Cu foil are sandwiched together with the double-sided acrylic tapes (3M, ~0.25mm). The nylon film serves as the separator to insulate the transparent electrode and Cu foil when the device is bent. For the 6 cm × 6 cm large-scale device, Cu tape is used on the four edges of the graphene to reduce the potential drop of the transparent electrode.