A structure and a method for operating the same. The method comprises providing a resistive/reflective region on a substrate, wherein the resistive/reflective region comprises a material having a characteristic of changing the material's reflectance due to the material absorbing heat; sending an electric current through the resistive/reflective region so as to cause a reflectance change in the resistive/reflective region from a first reflectance value to a second reflectance value different from the first reflectance value; and optically reading the reflectance change in the resistive/reflective region.