Nanogenerator Converts Body’s Energy into DC Output

Researchers from Georgia Tech have developed a generator of DC electricity that can convert kinetic energy from the body (blood flow, or muscle movements) into current to power implanted nano-medgadgets of the future.

Researchers have demonstrated a prototype nanometer-scale generator that produces continuous direct-current electricity by harvesting mechanical energy from such environmental sources as ultrasonic waves, mechanical vibration or blood flow.
Based on arrays of vertically-aligned zinc oxide nanowires that move inside a novel “zig-zag” plate electrode, the nanogenerators could provide a new way to power nanoscale devices without batteries or other external power sources.
“This is a major step toward a portable, adaptable and cost-effective technology for powering nanoscale devices,” said Zhong Lin Wang, Regents’ Professor in the School of Materials Science and Engineering at the Georgia Institute of Technology. “There has been a lot of interest in making nanodevices, but we have tended not to think about how to power them. Our nanogenerator allows us to harvest or recycle energy from many sources to power these devices.”
Details of the nanogenerator are reported in the April 6 issue of the journal Science…
The nanogenerators take advantage of the unique coupled piezoelectric and semiconducting properties of zinc oxide nanostructures, which produce small electrical charges when they are flexed.
Fabrication begins with growing an array of vertically-aligned nanowires approximately a half-micron apart on gallium arsenide, sapphire or a flexible polymer substrate. A layer of zinc oxide is grown on top of substrate to collect the current. The researchers also fabricate silicon “zig-zag” electrodes, which contain thousands of nanometer-scale tips made conductive by a platinum coating.
The electrode is then lowered on top of the nanowire array, leaving just enough space so that a significant number of the nanowires are free to flex within the gaps created by the tips. Moved by mechanical energy such as waves or vibration, the nanowires periodically contact the tips, transferring their electrical charges. By capturing the tiny amounts of current produced by hundreds of nanowires kept in motion, the generators produce a direct current output in the nano-Ampere range.

Press release: Nanogenerator Provides Continuous Electrical Power …
The National Science Foundation: Miniscule Generators Convert Motion Into Nanoscale Electricity Source …