It's pretty easy to find the "working principle" of surface capacitive touchscreen like http://www.elotouch.com/Technologies/SurfaceCapacitive/howitworks.asp [Broken] Roughly speaking, I know that A surface capacitive touchscreen has a conductive layer to which some electrodes are attached The electrodes apply voltage across the layer When some conductive material, e.g. finger touches the layer a portion of current is drawn yielding numbers' changes in the sensors attached to the electrodes According to the numbers read from sensors, one calculates the touch location Here're the questions: Should the electrodes apply DC or AC signals to the layer? How is the "conductive layer" modeled, i.e. is it regarded as a 2D conductive plane ? Or is it regarded as a 3D conductive block? In either case, how to calculate or approximately guess the charge/voltage/current distribution when the layer is idle/touched? What are proper sensors to attach to the electrodes, e.g. voltage metres or current metres or sth else? Why?