Voice Powered Mobile Phones ?
Cell phones that can convert the sound of your voice into energy to run the phone may be coming ... Research at Texas A&M by Tahir Cagin is getting closer to self powered devices like cell phones "... converts sound waves ... into the energy it needs to keep running. ...Utilizing ..."piezoelectrics," ... a certain type of piezoelectric material can covert energy at a 100 percent increase when manufactured at a very small size – in this case, around 21 nanometers in thickness.
" ... piezoelectrics are materials (usually crystals or ceramics) that generate voltage when a form of mechanical stress is applied. "
Via: Texas A&M Chemical Engineering LINK