A sensor stimulated by structural change

Hey, I am not from electrical engineering branch so I need some insights from you guys. I have some knowledge about how touch screens work(capacitive touch screens). I thought to work on an idea to build a sensor which can detect changes caused due to flexing of structural integrity and detect delta movements, like a muscle movement. I know there are electronic sensors which detect electrical signals to muscles but I want something which is cheaper to build and more practical to use.
Something like a thin patch or strip.