There are other mechanisms other than "pushing" that can generate pressure waves to spark energy in piezoelectric materials. Imagine a self-powering cell phone, for instance, that never needs to be charged because it converts sound waves produced by the user into the energy it needs to keep running.

Some night clubs in Europe now feature dance floors built with piezoelectrics that absorb and convert energy from footsteps in order to help power lights in the club. And a Hong Kong gym reportedly is using the technology to convery energy from exercisers to help power its lights and music.
Tahir Cagin and his partners study the piezoelectric concept. For this project, they fine-tuned piezoelectric materials with nanoscale dimensions . Studying piezoelectrics in microscopic units is a relatively new endeavor, but a key step along the road toward inventing a self-powering cell phone and other portable, high-tech devices, which contain these minute components already.