There are several technologies to create a touch-sensitive screen, some based on light or sound waves, conductivity and other electrical charge, on other cameras.
The easiest way is resistive. Two layers of plastic close contact on a grid of conductors, when pressed. The position on the X and Y and the pressure exerted on the elements of the grid, is used to interact with the images on the screen.
The capacitive touch screen that we’re all learning to use, what allows us to touch more fingers (the multi-touch) and that the success of the iPhone, is based on the variation of the electric charge on the glass screen. Our fingers conduct electricity and are able to alter the electrical charge on the touchscreen display, arranged in a grid of contacts (to be precise a grid of electrical capacitors). Thanks to a sophisticated tracking system, you can detect the touch and direction of movement of touch, so as to follow the gestures of movement.
The capacitive touchscreen does not work with gloves or plastic objects, so you can not use classic nib of the tablet. In fact, there are some solutions to remedy the problem.
For example you can use a 1.5 volt battery as a stylus. Just bring the negative pole (the plate with – sign) to the surface-screen and you’re done!
Our interactive display works with the resistive touch screen with capacitive ones.
Source Technology inside