You may no longer need to worry about your cellphone battery getting down, as you can now charge it by just shaking it.

An Indian origin scientist and his colleagues at Virginia Tech in Blacksburg are designing a new cellphone charger that turns movement into energy.

Shashank Priya and his team's emergency onboard charger 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 operate a phone - but would be sufficient for an emergency situation, said Priya.

"In an emergency you could just shake your cellphone for a few minutes to get enough power to make this one important call," New Scientist quoted him as saying.