A method of making a touch sensor assembly comprises: forming conductive trace elements on a transparent substrate; forming an insulator layer on the transparent substrate such that the insulator layer covers a portion of the conductive trace elements; and forming a plurality of conductive bridging lines such that each of the conductive bridging lines bridges two corresponding ones of the conductive trace elements. Each of the conductive bridging lines includes a plurality of conductor layers stacked one above the other and differing from one another in reflectivity. One of the conductor layers is formed by reacting a reactive gas with a metallic material, and has a reflectivity less than that of the metallic material.