1Two things to know first
You carry electricity, and the glass is full of it too
Two simple ideas unlock the whole trick. Watch each one:
You're a little wet wire
Your body is full of salty water, and salty water carries electricity. So your skin can quietly sip a tiny bit of electric charge — like a straw.
The glass hides a grid
Under the glass is an invisible grid of tiny electric squares, each holding a little puddle of charge — waiting for something to sip from it.
2The two kinds of touch
Some things can sip electricity. Some can't.
Stuff that carries electricity
Your finger, a wet finger, a metal spoon — all conductors. When they touch the glass, they sip a little charge from the square right under them. The grid feels the puddle shrink, and knows: someone's here!
Stuff that can't carry electricity
A wool glove, a plastic pencil tip — insulators. They press on the glass just fine, but no charge can flow into them. The puddle stays full. To the grid, it's like nothing touched at all.
3Your turn — tap the screen
Pick a toucher, then tap a spot
This is a pretend phone with its hidden grid switched on so you can see it. Choose what touches the glass, then tap anywhere on the screen. Watch the charge meter.
Tap a spot on the screen above.
4Now try to fool it
The big test: does a glove work? 🧤
Here's the showdown. You'll put on a wool glove and mash the screen as hard as you can. Then you'll touch it with a bare finger as gently as you can. Guess first!
Guess before you find out
You tap the screen wearing a thick wool glove and press really hard. Does the screen notice your tap?
Drag the slider, then tap the screen below with each toucher.
5So is sensing electricity perfect?
It's clever — but it has a price
Because it reads charge and not force, the lightest brush works, and it can follow many fingers at once — that's how pinch and zoom work.
Anything that can't carry electricity is invisible to it: a glove, a plastic stylus, a touch through a thick case.
A touchscreen doesn't feel you push — it feels your body sip a tiny bit of electricity. So only things that carry electricity, like your skin, can talk to it. That's why a glove can press as hard as it likes and the screen stays blind.
Psst, grown-ups: modern phones use projected-capacitive sensing. A transparent grid of electrodes (usually indium tin oxide) holds a small charge, and a grounded conductor — your finger, grounded through your body — changes the capacitance at the nearest grid crossing. A controller scans the grid many times a second, measures the dip in stored charge, and triangulates the position. Pressure is irrelevant, which is why insulating gloves fail, conductive-tip styluses work, and stray water droplets can register false touches.