UW Engineers Invent First Tree-Powered Circuit

September 10th, 2009 by Michael Ricciardi

In a first, researchers at the University of Washington in Seattle have developed a completely tree-powered electrical circuit.

The nano-scale device—approximately 130 nanometers [a nanometer is one billionth of a meter] in size—consumes just 10 billionths of a watt (10 nanowatts).

Unlike the legendary science fair experiment in which a potato-based electric circuit is created using two electrodes (each electrode being a different metal, which react with the starch, causing a potential difference and thus a current), the UW device utilizes electrodes comprised of the same metal, and is able to generate (output) 1.1 volts. “As far as we know, this is the first peer-reviewed paper of someone powering something entirely by sticking electrodes into a tree,” according to paper co-author Babak Parviz, associate professor of electrical engineering at the UW.

Last year, researchers at MIT discovered that a constant current of about 200 millivolts (a millivolt is one thousandth of a volt) is generated between plant and soil. But that work did not involve attempting to power any device or circuit, which would require making a device capable of running (performing some function) on exceedingly low voltages.

The UW researchers sought to apply this knowledge to power an actual device. In seeking an ideal candidate power source under-graduate student Carlton Himes discovered that the broad-leaf Maple tree (common in the area) supplied a steady voltage of a few hundred millivolts. Despite this, the researchers realized that they would need a bit more juice to power a such circuit.

To solve this challenge, co-author and UW assistant professor of electrical engineering Brian Otis led a team that developed a “boost converter” which takes the low incoming voltage and stores it to produce a stronger output. The device is able to work with voltages as low as 20 millivolts and can output 1.1 volts–enough to power a small sensor that can be used to take the “pulse” of the tree (its periodic pulsing of electrical energy) which may indicate its overall health.

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Tags: biology, Electricity, National Science Foundation, tree-power, trees, UW

About the Author

Michael Ricciardi Michael Ricciardi is a well-published writer of science/nature/technology articles as well as essays, poetry and short fiction. Michael has interviewed dozen of scientists from many scientific fields, including Brain Greene, Paul Steinhardt, Arthur Shapiro, and Nobel Laureate Ilya Progogine (deceased). Michael was trained as a naturalist and taught ecology and natural science on Cape Cod, Mass. from 1986-1991. His first arts grant was for production of the environmental (video) documentary 'The Jones River - A Natural History', 1987-88 (Kingston, Mass.). Michael is an award winning, internationally screened video artist. Two of his more recent short videos; 'A Time of Water Bountiful' and 'My Name is HAM' (an "imagined memoir" about the first chimp in space), and several other short videos, can be viewed on his website (http://www.chaosmosis.net). He is also the author of the (Kindle) ebook: Artful Survival ~ Creative Options for Chaotic Times