Need to make a call but run out of juice? Just give your
cellphone a shake for an extra burst of power - that's the idea
behind a new cellphone charger that turns movement into energy.
Shashank Priya and his colleagues at Virginia Tech in Blacksburg
are designing an emergency onboard charger that draws energy
from the piezoelectric force generated by your fingertips
clicking the keypad, your voice - or just by giving the phone a
good old shake. The researchers experimented with zinc oxide, a
common piezoelectric material, to see how well it converts
vibrations from sound and pressure waves into energy to power a
phone. They subjected the material to sound waves of 100
decibels, which made the material vibrate and produce an
electrical current at about 50 millivolts. In a cellphone, the
piezoelectric material would be mounted below the keys and
convert mechanical vibrations into energy that could be stored
for later use. It wouldn't produce a great deal of power -
certainly not nearly enough to continuously op