One of the teams’ challenges in constructing a working sensor was that the device had to spend considerable time in “sleep mode” to conserve its limited power supply. This was problematic in that something was needed to “wake” the system up so it can do what it was intended to do. To solve this problem, the team invented a tiny clock mechanism to periodically wake the device up. The clock runs continuously on just 1 nanowatt of power, and, when fully turned on, uses just 350 millivolts (about one quarter the power of a AA battery).
Parviz points out that the nano-scale is not just a matter of size, but also one of power usage, and he anticipates more uses for such devices as a new generation of nano-electronics comes on-line.
The exact cause of this electrical tree power is not entirely understood but may involve the flow of dissolved mineral ions in the tree’s xylem–the specialized cells just inside of the tree’s cambium layer that transport water. And although too weak to ever replace solar power, tree-power can be used to monitor forest health, one tree at a time, and perhaps also monitor other signals from the environment (such as soil oxygen content, chemical signals from disease-causing pathogens, or heat increases that might indicate fire).
Additional co-authors of the paper include Eric Carlson and Ryan Ricchiuti, also of the UW. Research was funded in part by the National Science Foundation.
Photo Credit: University of Washington
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About Michael Ricciardi
