Question: How do touch screens work? And how do only some objects work with them? e.g. Your fingers can use it, but not while you are wearing gloves.

Anna Bramwell-Dicks answered on 16 Jun 2014:

There are actually different types of touch screen which work in slightly different ways. I’ll give you a quick explanation of the 2 main types…

First, there are “resistive” touch screens. These contain two separate layers of material with a small gap between them, underneath a scratch proof surface. When you touch the surface layer, you put pressure on the two layers underneath, which get squished together making a connection between them. When the two layers touch, the device notes that there is a change in the amount of electrical current going to the screen at that particular location.

So with the resistive type of touch screen, you CAN use gloves, because it is the physical action of connecting the layers which provides the location!

More commonly now though, are “capacitive” touch screens (like in the iPhone, or iPad). These just have a single layer, of a material that conducts electricity (it’s made from a capacitive material). When the device is turned on, an electromagnetic field is created. When you touch the screen, your finger (which acts as a conductor of electricity) disturbs that electromagnetic field which allows the device to work out where the touch occurred.

However, with capacitive touch screens, you are right that gloves don’t work. Why is this? Well, that’s a very good question! The material in the glove acts as an insulator between the finger and the device screen, which stops the finger from affecting the electromagnetic field, so the device does not know where the finger is! You can actually buy special gloves, which include a capacitive material in the fingertip. Or you can just use fingerless gloves, like I do 🙂