| Pace-Setting
Nanotubes May Power Micro-Devices
By Mike Martin
NewsFactor Sci::Tech,
Part
of the NewsFactor Network
February 27,
2003
Inner-space journeys, such as that envisioned
by Harry Kleiner and Isaac Asimov in "Fantastic Voyage," might
become possible with nanotube-powered micro-submarines that use
flowing blood as both a power source and a medium of transport.
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New measurements by an Indian
physicist and his team support the idea that nanotubes --
cylindrical carbon rolls no thicker than an atom -- may make good
batteries  for tiny devices or even power pacemakers,
dispensing with cumbersome power packs.
Submersed in a slow-flowing liquid, a dense bundle of nanotubes
develops a voltage that ranges up to 10 millivolts and increases
with flow speed, according to Ajay Sood and his colleagues at the Indian Institute of Science in
Bangalore.
The tiny turbine "is made of single-wall carbon nanotubes," Sood
told NewsFactor. "Measurements are reported in Sciencexpress,
showing the generation of voltage by fluid flow."
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 | When 8 Times the Size of
the National Debt Means Ultra-Small
A nanotube is so small that a bundle the size of a sesame seed
contains about 50 trillion tubes -- eight times the size of the U.S.
national debt. As various fluids, from hydrochloric acid to water,
flowed over a nanotube bundle mounted between metal electrodes, Sood
and his team measured the generated voltage.
Hydrochloric acid produces voltages about five times that of
purified water and 60 times that of methanol, Sood observed.
Methanol and water are poorly ionized liquids, while hydrochloric
acid contains abundant hydrogen ions. Imbalances that develop
between positive and negative charges as liquids flow over the tubes
probably cause the voltage to develop, Sood hypothesizes. More ions
create a greater charge difference and hence a greater voltage.
Fantastic Change of
Pace
Charge-generating nanotubes may find applications in
micro-machines that work in a fluid -- and futuristic --
environment. While nano-explorers have yet to be invented,
inner-space journeys, such as that envisioned by Harry Kleiner and
Isaac Asimov in "Fantastic Voyage," might become possible with
nanotube-powered micro-submarines that use flowing blood as both a
power source and a medium of transport.
In the nearer future, nanotube turbines might power a new,
lightweight line of heart pacemakers that need neither heavy battery
packs nor recharging.
"It sounds great that this is emerging pacemaker technology  that avoids a battery," said Dr. Nieca
Goldberg, chief of the Cardiac Rehabilitation and Prevention Center
at Lenox Hill Hospital in New York. "It would reduce the need for
surgical procedures to change the pacemaker battery, which is
usually required at an average time of five years," Goldberg told
NewsFactor.
Radical
Batteries
Rolled nanotubes also lend themselves to three-dimensional
batteries that can be made extra small.
"The electrodes in today's small batteries are made flat (or as
multilayer sandwiches of flat electrodes at best)," said UCLA engineering professor Chang-Jin
"CJ" Kim, a micro-fabrication and nanotechnology expert. "With the
recent advances in micro-machining technologies and emerging
nanotechnologies, we are exploring a new concept of using
three-dimensional electrodes in designing small batteries, a radical
departure from the existing practice of mating two flat plates," Kim
told NewsFactor.
Confident that nanotubes will set the pace for many new
technologies, Dr. Sood said he is "in the process of patenting the
concept in both India and the United States." 
| 
March 05, 2003 
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