E-field (Capacitive) Sensing Foot Switch

The previous examples use the same physical sensing
principle: gesture modulating current flow. Capacitive or e-field
proximity sensing is an interesting alternative principle to apply
for rapid prototyping. Only one conductor is needed and more
flexibility about where the conductor is placed is available. It
can be under glass, plastic or wood or other non-conducting
material.
[inline-left:capacitive.jpg]
This foot switch can be assembled in less than a minute. A wire with a crocodile clip is attached to a conductive spandex fabric (http://eeonyx.com) that is stuffed inside a length of clear plastic
door insulation strip. The fabric needn’t be very conductive for this to work well as no current flows through it.