Good Vibrations

Converting small vibrations into electricity to power batteries in remote electronic devices.

Aug 17, 2009

By Phillip F. Schewe
Inside Science News Service

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A generator for converting vibrations into electricity. A vibrating object, such as an airplane wing, causes a tiny magnetic sliver to oscillate past two magnets (green pads to the right). This motion, in turn, generates a tiny bit of alternating-current (AC) electricity inside a pair of special crystals. The AC electricity is then converted into the kind of direct-current (DC) electricity needed by an electrical device such as a light bulb or a sensor

WASHINGTON -- A new device that can harvest useful energy from extremely tiny vibrations may allow new ways to power remote electronic devices with batteries that need replacing less often, or are actually self-charging. The "vibration-to-electricity" device could capture up to 10 times more energy than is possible with the conventional device.

Scientists at the Virginia Polytechnic Institute in Blacksburg, Va., used a process well known in science called the "piezoelectric" effect, a phenomenon in which certain crystals and other materials, when twisted or flexed, actually generate electricity. The new device increases the range of vibration frequencies from which energy can be captured. Conventional "piezo-generators" only efficiently harvest energy at certain frequencies, severely limiting the amount of power they can capture and generate.

The graduate student working on the project, Alper Erturk, said that the prototype device gets its 10-fold increase in energy generation by working acceptably at frequencies that conventional piezo-generators can't access efficiently.

Erturk said that his lab is working on two government-sponsored projects. One, supported by the U.S. Air Force, is for unmanned air vehicles.  A tiny device attached to wing spars will convert wing vibration into electricity. The other project, sponsored by the National Institute of Standards and Technology, is for bridges and would use power from traffic vibrations to create the electricity needed to power sensors that can detect cracks in the structures.

These results appeared recently in an issue of the journal Applied Physics Letters.