How good is the touch screen? It’s hard to remember a time without it. Touch screen works because your finger holds electrical current and creates an electrical conduit. So, it’s nothing to do with pressure and more to do with heat. You may have found when your phone has been in your pocket with the glass facing your body, that it is hard to get working properly. When this happens try blowing on the screen, this can help it recalibrate.
As smart as the phone is, it doesn’t actually know that it is your finger touching the screen, it just knows it is something about the same level of conductivity as a finger. You can have some fun trying things which hold a similiar charge to a human finger…a banana will work.
