Pro-cap is a solid-state technology, which means that it has no moving parts (unlike the resistive touch technology). Instead of being based on electrical resistance, it relies on electrical capacitance.

When you apply an electrical charge to an object, the charge can build up if there is no place for the electrons to flow. This "holding" of electrons is known as "capacitance." You have probably experienced this effect first-hand. When you walk across a carpet in rubber-soled shoes in the winter time, electrons can build up in your body. If you should then reach for a light switch or some other conductive object that does not have a similar built-up charge, those electrons can flow from your body to the object, producing a spark of electricity.

If you apply a charge to a conductor, and then bring another conductor near it, the second conductor will "steal" some of the charge from the first one, just as the light switch did when your finger approached it. If you know what the charge was to start with, you can tell when the amount of the charge has changed. This is the principle behind pro-cap touch screens.

Early capacitance touch technologies required that you actually touch a conductive layer. This approach left the conductor exposed to wear and damage. Today's projective capacitance technology relies on the fact that an electromagnetic field "projects" above the plane of the conductive sensor layer. You can cover the touch module with a sheet of thin glass, for example, and it will still sense when a conductor comes near.

Pro-cap touch screens use two layers of conductors, separated by an insulator (such as a thin sheet of glass, though other insulating layers can be used). The conductors typically are made of transparent ITO, just as with the resistive designs. The conductor layers never have to bend, however, so its brittle nature is not a problem with pro-cap screens.