It doesn't use any specific sensor, rather the comparators inside the PIC.. If there are many capacitive areas, they multiplex the comparator. Check this link out:
http://www.microchip.com/stellent/id...param=en535171

It tells all you want to know (and more) about the concept.

I've done 4 wire resistive touch controllers with a PIC, but this is much cheaper to implement. Just copper squares on the backside of a circuit board, with your PIC and such, on the top...

JR