When exploring sensors for reading out behavioral (i.e. motor) output from an animal, I came across bend sensors that can be incorporated into clothing (http://www.talk2myshirt.com/blog/archives/724). By using thin copper foil, velostat, and epoxy, I was able to shrink the dimensions of the sensor to about 15 mm length. Unfortunatly, I needed something even smaller, and something more compliant. But here's the basic idea: