Why can you still use your phone screen when it’s blocked by something like an elastic piece?

Question

Why can you still use your phone screen when it’s blocked by something like an elastic piece?

In: Technology

Answer 1

Touchscreens measure capacitance, which is when you have an insulator (the glass) in between two conductors (the touchscreen circuitry under the glass and your finger). If you cover your finger with a very thin insulator, it can still detect the effect of your finger on the underlying circuitry since it most of the insulation is from the glass. It’s only when you have a thicker insulator that your finger won’t register.