A process found in plants may contain a new source of electrical energy that could eventually power personal electronics, according to a new study led by UC Berkeley Assistant Professor of Electrical Engineering Michel Maharbiz.

The study conducted at UC Berkeley and the University of Michigan, Ann Arbor was funded by grants from The National Science Foundation and the U.S. Army for application in robotics. The study found that evaporating water on plant leaves can be harnessed to produce electricity. Though the amount generated is small, the discovery still has big potential for consumers who might eventually use an advanced form in electronic devices, Maharbiz said.

Plants naturally go through a process known as "transpiration" where they draw water from roots and distribute it to the leaves. The water eventually seeps out and evaporates, according to the study.

Maharbiz said that his team utilized transpiration by creating a glass replica of a leaf, complete with veins. Water flowing through the channels carries a bubble to two electrical circuits that transform friction into an electrical charge.

"I was looking at a book about ferns and how ferns have little structures that shoot spores when the season comes," Maharbiz said. "I thought we should build a little machine based on that ... it's a concept that's never been demonstrated before."

But some say that further research is necessary before plant-based technology can feasibly be applied to clocks, flashlights and other small devices as Maharbiz says.

Abraham Stroock, associate professor of chemical and bioengineering at Cornell University who works with plants at the molecular level, said in an e-mail that any future breakthroughs in the technology must overcome inherent inefficiencies.

"Bubbles are the worst enemy of the transpiration process (in nature)," he said. "They will often completely halt the flow ... most of this energy input will be lost."

But he conceded that the technology was still compelling.

"This is a nice example (of) harvesting energy from a fluctuating process in the environment," Stroock said in the e-mail.

Maharbiz said that follow-up research is already under way, which will deal with more specific obstacles in improving the technique.

"The next step is to have an experiment that uses (few) bubbles," said Maharbiz. "Bubbles are not feasible for a (long-term) commercial device."

Although he said in the e-mail that the public is eager to see the outcome of the study, Stroock said that time is needed before concrete results are realized.

"It is not a technological breakthrough, yet," he said.

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