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7 February 2011
Author: Giorgos Lazaridis
PIC Capacitance Sensor with 4 buttons and Multitouch Function

The hardware

 I use a piece of aluminum foil and a piece of plexiglas First, i cut 4 pieces of the foil, about 1 by 2 cm each Then, i cut a larger one that completely covers the plexiglas. Notice that i left a long strip to connect the alligator I glued this piece on one side of the plexiglas (notice the long strip for the alligator) On the other side, i glued the 4 strips. Half of them on the plexiglas and half remain floating for the alligators This is how the alligators are connected. The 4 alligators from the electrodes goes to the 4 inputs, the one from the larger piece goes to ground A piece of glass is placed ontop

It is more than simple to make a capacitance touch electrode, and it is more than fun to make the artwork. Between the glass and the electrodes, any insulating material can be used, like for example paper. I used a piece of thick paper with 4 buttons drawn:

Instead of glass, you can for example use plexiglas or any other plastic material, or wood, with the drawings engraved on it. Any insulating material will do, always preferring those with high dielectric constant.

Multitouch!!!

Yes, indeed, multitouch! No matter how many electrodes you "touch" the circuit will normally work. You can use as many fingers as you like :D.

 One button touched Two buttons touched Three buttons... One finger to touch them all, one ring to rule them all.

Applications for this? Simply, numberless. Imagine that you can make a 4 by 4 surface with 16 (4x4) touch electrodes and have a multitouch pad! Or add more PICs to have larger areas, or use matrix techniques to have an 8 by 8 matrix with one PIC, or 16 by 16 with two... It is so amazing, and it is dead cheap as well!