http://www.sciencemag.org/cgi/content/abstract/319/5864/807
Science 8 February 2008:
Vol. 319. no. 5864, pp. 807 - 810
DOI: 10.1126/science.1149860
Biomechanical Energy Harvesting: Generating Electricity During Walking
with Minimal User Effort
J. M. Donelan,1* Q. Li,1 V. Naing,1 J. A. Hoffer,1 D. J. Weber,2 A. D. Kuo3
We have developed a biomechanical energy harvester that generates
electricity during human walking with little extra effort. Unlike
conventional human-powered generators that use positive muscle work, our
technology assists muscles in performing negative work, analogous to
regenerative braking in hybrid cars, where energy normally dissipated
during braking drives a generator instead. The energy harvester mounts
at the knee and selectively engages power generation at the end of the
swing phase, thus assisting deceleration of the joint. Test subjects
walking with one device on each leg produced an average of 5 watts of
electricity, which is about 10 times that of shoe-mounted devices. The
cost of harvesting—the additional metabolic power required to produce 1
watt of electricity—is less than one-eighth of that for conventional
human power generation. Producing substantial electricity with little
extra effort makes this method well-suited for charging powered
prosthetic limbs and other portable medical devices.
1 School of Kinesiology, Simon Fraser University (SFU), Burnaby, BC V5A
1S6, Canada.
2 Department of Physical Medicine and Rehabilitation, University of
Pittsburgh, Pittsburgh, PA 15213, USA.
3 Departments of Mechanical Engineering and Biomedical Engineering,
University of Michigan, Ann Arbor, MI 48109, USA.
* To whom correspondence should be addressed. E-mail: [EMAIL PROTECTED]
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((Udhay Shankar N)) ((udhay @ pobox.com)) ((www.digeratus.com))
