Surface Accoustic Wave (SAW)
SAW touch screens rely upon sound waves; thus, sound wave reflectors are placed along the edges of the glass. Two send transduceers are placed in two of the corners, and two receiving transducers are mounted in the opposite corners. A sound wave travels parallel to the edges of the glass. The controller listens using sonar technology for a distortion in the sound wave. Based on the time of this deflection and knowing the speed of sound, the location of the touch is determined. There are NO CONDUCTORS, nothing to patter, thereby nothing to break down. This is simply a piece of glass. This is a very durable product, but does have some issues when used in a high moisture environment.