The Deal

• $iPad or Samsung Tablet Screen Repair, (a $ value)

Touchscreens: Power at Your Fingertips

To learn what's behind the face your smartphone shows to the world, read on.

Most electronic touchscreens—such as the kind on your smartphone, perhaps—rely on electricity. Not just the obvious electricity provided by their power supply, but your electricity, as in the tiny amount that runs through your body or the large amount that runs through your body if you're a Frankenstein. Capacitive touchscreens are set up to detect any change in the electromagnetic field they produce, such as that created by a bare fingertip. Beneath the glass screen, a network of electrodes stands ready to relay information about the location of the touch to the device’s microcontrollers and translate it into a command.

Another Path: Resistance

There is another, slightly older form of touchscreen technology, which requires the hand to apply not electricity but pressure. This type is known as a resistive screen and is frequently still found at checkout counters and on PDAs. Beneath its surface are two layers of conductive material. Pressure forces the two layers to connect, completing a circuit; different points on the screen will produce a current with different voltage, which allows the system to pinpoint the precise location of the touch. Although these screens are lower-resolution and can't respond to multiple simultaneous touches, they do have one advantage over capacitive screens: they'll work even if you're wearing gloves or oven mitts.

Bonus Points

• There are plenty of other, less common ways to create a touchscreen. Some devices send ultrasonic waves continually across the screen, which are interrupted upon contact; others, including Microsoft's Surface tabletop screen, sense changes not in pressure or electric charge but in light.
• Capacitive screens have also been developed that can register how hard you're pressing. When you press down harder on anything you'll notice your fingertip spread out to contact more of the surface. Newer screens take advantage of this fact and track whether you're contacting an increasing number of capacitors.