Apple worked closely with Corning, the makers of Gorilla Glass, to develop a pliable glass for the new iPhone's glass cover.

Pressing down onto the glass bends the glass very slightly at the point of contact, shortening the distance between your finger and the corresponding capacitor plate in the array beneath the display. This registers a "push" rather than a "touch".

In a parallel plate capacitor, capacitance is inversely proportional to distance—a shorter distance means greater capacity for charge on the plate, so the IC would measure an inflow of current to the sensor board.

While the plates are similar to those in a touch screen, they are too large to pinpoint a finger press. Luckily they don't have to.

The "real" digitizer is still present for precision tracking, these plates only have to detect a flex in the glass—not where it occurs.