I have an application where I need to sense four touch pads with a PIC.
These pads should react to very light touch, or even just proximity,
so (mechanical) membrane switches are inadequate.

I'm thinking of the following approaches:
- Optical: Sensing the proximity of a finger with a photoreflector
- Inductive/Capacitive: Presence of a finger changes inductance/capacitance
  in an oscillator, which changes the frequency

I would be interested in hearing if anyone has suggestions and
experience of this problem. Noise and ESD are factors.

Martin Nilsson                           http://www.sics.se/~mn/
Swedish Institute of Computer Science    E-mail: mn@sics.se
Box 1263, S-164 28 Kista                 Fax: +46-8-751-7230
Sweden                                   Tel: +46-8-752-1574