As it turns out, two of these technologies dominate the market for transparent touch technology applied to display screens in mobile devices. And the two approaches have very distinct differences. One requires moving parts, while the other is solid state. One relies on electrical resistance to sense touches, while the other relies on electrical capacitance. One is analog and the other is digital. (Analog approaches measure a change in the value of a signal, such as the voltage, while digital technologies rely on the binary choice between the presence and absence of a signal.) Their respective advantages and disadvantages present clearly different experiences to end users.

Resistive touch

The traditional touch screen technology is analog resistive. Electrical resistance refers to how easily electricity can pass through a material. These panels work by detecting how much the resistance to current changes when a point is touched.

This process is accomplished by having two separate layers. Typically, the bottom layer is made of glass and the top layer is a plastic film. When you push down on the film, it makes contact with the glass and completes a circuit.

The glass and plastic film are each covered with a grid of electrical conductors. These can be fine metal wires, but more often they are made of a thin film of transparent conductor material. In most cases, this material is indium tin oxide (ITO). The electrodes on the two layers run at right angles to each other: parallel conductors run in one direction on the glass sheet and at right angles to those on the plastic film.