Thanks to a very good explanation by Mr. Ghosh, I found that a capacitive touchscreen measures the change in capacity, induced by contact with a conductive material, along a grid. I have two questions:
- If the capacitance is measured using a high-frequency signal, would it be possible to (indirectly) measure natural electrical signals (low frequency) from the body using the same system? I am interested in using mobile phones to measure these signals.
- Is the change in capacitance dependent on the local composition of the body part that touches the screen?