[sdiy] Polyphonic touch panels? Capacitive relaxation osc method?

[KD KD]

Is it possible to use capacitive sensing on 8x8mm PCB pads and the
relaxation oscillator
method for 80 touch buttons on a grid of 10x10mm? I haven't done any
calculations on this
but estimate the osc need to buzz around a 1-1.5Mhz due to distances
between buttons.
Or must the pads be larger,and further spaced away from each other? I
tough i could
anding them together to save I/O ports. I have some various papers on
the subject
but none speaks about very short distances.

Ideas?
KD

( Thank's for the previous info, Veronica, Collin.)