The example shown here consists of a PCB with electrodes that are just plain copper pads. Then, on top of it, there is an insulating layer, which could be glass, plexiglass or other plastic material. There is then an optional layer with a silk screen printing, on which all of the icons, numbers, or whatever is desired on the user interface. In this case, the sensor is just the copper pad connected through a trace to the input of the actual controller.