Shaking aspen leaves inspire new energy harvesting device

March 18 (UPI) -- Inspired by aspen leaves, which tremble in the slightest of breezes, scientists at the University of Warwick have developed a leaf-shaped energy harvester.

Researchers suggest the device could power weather sensors in hostile environments, like those deployed by Martian rovers.

"What's most appealing about this mechanism is that it provides a mechanical means of generating power without the use of bearings, which can cease to work in environments with extreme cold, heat, dust or sand," Sam Tucker Harvey, PhD engineering researcher at Warwick, said in a news release. "While the amount of potential power that could be generated is small, it would be more than enough to power autonomous electrical devices, such as those in wireless sensor networks."

Harvey and his research partners used computer models to better understand the unique sensitivity of aspen leaves to wind. The analysis showed the leaf's thin, flat stem plays an important roll. The stem's tendency to twist in two directions causes the long, thin leaf below to quiver.

Armed with their new knowledge, scientists designed a model to produce a mechanical representation of an aspen leaf. They produced a device characterized by a flat stem, cantilever beam, curved blade tip and an arced cross section.

Scientists tested the leaf-like device in a wind tunnel. When positioned perpendicular to the air flow, the device's curved blade oscillated at low wind speeds.

The device could be used to as a backup power source for rovers on Mars. Last month, NASA's oldest rover, Opportunity, was pronounced dead. Researchers estimate its batteries were drained after a Martian dust storm prevented its solar panels from harvesting the sun's energy.

"The performance of the Mars rover Opportunity far exceeded its designers' wildest dreams but even its hard working solar panels were probably eventually overcome by a planetary-scale dust storm. If we could equip future rovers with a backup mechanical energy harvester based on this technology, it may further the lives of the next generation of Mars rovers and landers."

Researchers described their new leaf-like energy harvester this week in the journal Applied Physical Letters.