When your finger touches the keys of the ipod, the capacitance will change, and its control IC will detect the capacitance change and convert it into direction.
This touch key is sensitive to the heat of fingers through capacitive induction. Why not try with the back of your hand? No, the resistance of the back of the hand is a little higher than that of the fingers, but it will be fine when it is wet)
When a finger touches it, the electrostatic field on the key will change.
The conductive layer of capacitive screen is often covered with a layer of Shi Ying glass, which has strong friction resistance. Because two conductors can conduct electricity when they are close together, they don't necessarily need direct contact, so it is easy to cause misoperation when the human body or other conductors are close together. For example, if you use a touch screen to make a phone call, you may hang up accidentally if your face touches the screen. It is precisely because of this factor that Apple's iPhone can detect people's facial features and automatically lock the screen when making a call. Another disadvantage of capacitive touch screen is that it can't be used if you wear gloves. People who have used LG "chocolate" mobile phones should have a deep understanding of this.