The Science Behind Capacitive Styluses

Jul 15, 2019

Not all touchscreen styluses are made of the same material. While many are made of plastic, others are made of a conductive material like copper or indium tin oxide (ITO). Known as a capacitive stylus, they are designed to work with capacitive touchscreens. But unless you’re familiar with capacitive styluses, you might be wondering how exactly they are able to trigger commands on capacitive touchscreens.

What Is a Capacitive Stylus?

A capacitive stylus is a special pen-like device that’s used to perform input commands on a capacitive touchscreen. Like other styluses, it resembles a writing utensil. Of course, capacitive styluses don’t actually write. Rather, you tap them against a touchscreen’s display interface to perform input commands, such as opening apps or selecting keys on a virtual keyboard.

Capacitive styluses are unique, however, because they work with capacitive touchscreens. As previously mentioned, capacitive styluses are made of an electrically conductive material. They may contain other, non-conductive materials like plastic. The actual tip, however, features a conductive surface that’s able to absorb some of the touchscreen’s electrostatic field, thus allowing the device to register the stylus’s touch commands.

The conductive material within a capacitive stylus means you can use it on a capacitive touchscreen. As you may know, capacitive touchscreens identify touch commands by measuring capacitance. Therefore, you can’t use any object to perform touch commands on them. You must use an electrically conductive object. Being that the human body is an excellent conductor of electricity, you can use your bare finger to perform touch commands on a capacitive touchscreen. Alternatively, though, you can use a capacitive stylus thanks to its electrically conductive tip.

Will a Capacitive Stylus Work With Non-Capacitive Touchscreens?

Absolutely! Even though they are called “capacitive styluses,” they work with nearly all touchscreens, including resistive and surface acoustic wave (SAW). If you press a capacitive stylus against a resistive touchscreen, it will force the touchscreen’s upper and bottom layers to make contact, which in turn triggers a touch command at that location. If you press a capacitive stylus against a SAW touchscreen, it will disrupt the ultrasonic sound waves at that location, which also results in a touch command.

A capacitive stylus is the same as any other stylus, only it works with capacitive touchscreen devices as well as other types of touchscreens. It features an electrically conductive tip that’s able to absorb some of the device’s electrostatic field.

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