How does a capacitive touch screen detect touch?

A capacitive touch screen detects touch primarily by measuring changes in electric current or capacitance when a finger approaches or touches the screen. The screen is coated with a transparent conductive layer, which stores electrical energy and generates an electrostatic field. When a conductive object, like a human finger, comes close to the screen, it disrupts this electrostatic field. This disruption results in a measurable change in capacitance at that specific location on the screen.

The technology relies on the conductivity of the human body, which allows the screen to interpret that change as input. This system is very sensitive and can detect touches from a finger or stylus but does not respond to non-conductive objects.

In contrast, the other options do not accurately describe how capacitive touch screens operate. The method of heat detection, circuit completion from pressure, and infrared sensors represent different technologies that are not applicable to capacitive touch screens.