Fredrik,
Interesting idea....I think this could be done fairly easily with a 4-layer board. A couple of things to watch out for.
- Make sure there are no vias that go from a CapTouch button on one side to the opposite side of the board. Vias can trigger the CapTouch.
- I would place a hatched ground layer underneath the button, to prevent the capacitor between the top layer and ground layer from having much larger capacitance than the capacitor between the top layer and the top layer ground.
It may also be interesting to add haptics, to indicate to the user they have in fact pressed both buttons.
Thanks,
Brian
