Tactiontape - Touch Sensitive Tape for Rapid Prototyping
Tactiontape is a one-dimensional touch sensor that curves.
It's designed to make building interactive physical prototypes easier, even ones with non-planar or complex surface geometry.
It functions as a flexible potentiometer and uses a strip of graphite to express a linearly resistive electrical signal, one that corresponds to how far along the tape you've touched.
Each sensor is hand-made using materials from an art supply store.
Here's a demo:
For purchasing, photos, and more detail: