Forum Post: Cap. touch: sense touch on both sides of PCB?

I am working on a PERS (personal emergency response system), and specifically a small battery-powered "panic button" type of device that will be carried in a lanyard around the neck.

Instead of physical buttons, I wanted to use a capacitive touch surface, with a twist: I want capacitive touch surfaces on two sides of the PCB, and require the user to touch both sides of the PCB (i.e. pinch it) for two seconds to trigger the "panic button" function.

Good idea?  Bad idea?  If good idea -- what is the best way to implement it -- 4-layer PCB with ground planes in the middle?

Thanks!