How is the location of a finger or more detected on a capacitive touch panel?
A capacitive touch screen measures capacity/resonant frequency of "flat plate" senslrs spread across the screen. Your finger touching the screen actually doesn't cause current to flow (that would be a resistive touch screen), but changes the capacitance between 2 microscopic plates.
There are many thousands (actually, several millions on modern displays) of capacitive sensors on each screen. To handle all of those wires, there is a separate MCU (processor) that is part of the 'touch sensor device.' That MCU goes through and checks each 'cell'/'element' in series, then sends information on which one(s) are being 'touched' out on a (usually) serial interface, with several dozen, to a few thousand, updates per second.


See the Wikipedia Article, and related links from that article, for further reading/information.