Scientists at Rice University have built molecular vehicles so
small that more than 20,000 of them could sit side-by-side on
a human hair.
Just what we need, in the hands of the same people who designed
DU weapons.
rkm
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http://www.nytimes.com/2005/10/21/technology/21cnd-nano.html
October 21, 2005
Scientists Build Tiny Vehicles for Molecular Passengers
By BARNABY J. FEDER
Scientists at Rice University have built molecular vehicles so
small that more than 20,000 of them could sit side-by-side on
a human hair.
The fleet consists of nanocars, nanotrucks capable of carrying
small-molecule payloads, and trimers that pivot on their three
axes. All of them roll on buckyballs, which are 60-atom,
soccer-ball-shaped spheres of pure carbon. Each axis pivots up
and down independently to allow the vehicles to negotiation
atomic potholes and mounds.
The work, which was first described earlier this month in the
online version of the journal Nano Letters, is the fruit of
more than eight years of research led by Prof. James M. Tour
into systems that could be used to build structures
molecule-by-molecule.
"This is it, you can't make anything smaller to transport
atoms around," Professor Tour said.
The vision of the Rice researchers, like many other
specialists working in nanotechnology, is of a world where new
materials can be fashioned by armies of tiny machines working
in organized ranks. This so-called "bottoms up" version of
manufacturing is patterned after biology and, in the view of
many researchers, it could be far more efficient than current
manufacturing systems.
Skeptics have said such molecular manufacturing will prove to
be impractical in most cases and may pose unexpected
environmental risks. But scientists working in the field
almost universally dismiss visions of nanomachines
proliferating into a deadly world-choking "gray goo" as
popularized in Michael Crichton's novel "Prey."
Nanotechnology derives its name from the nanometer, or
billionth of a meter. Nanoscale objects are tens to thousands
of molecules in size. While they consist of familiar
materials, the scale is so small that atomic forces affect
their behavior and strange, potentially valuable traits
emerge. The nanocars are immune to friction, for example,
because the buckyball wheels are a single molecule that cannot
be easily pulled apart into its 60 carbon atoms.
Professor Tour said the research marked the first time
anyone had demonstrated nanoscale structures that roll rather
than slide across a surface. The current generation of
vehicles can be set in motion by heating the gold surface on
which they sit to about 200 degrees Celsius. Absent any
outside force, it is unpredictable whether they will move
forward or backward, but once they start they will continue in
that direction as long as heat is applied.
But Rice's researchers have shown that they can control the
direction by applying an electrical field. They have also
built a tiny light-powered motor for the devices consisting of
30 carbon atoms and a handful of sulfur atoms, Mr. Tour said.
But that motor does not capture enough energy to move the
devices over the gold surface because the gold molecules
absorb most of the light.
The nanocars are 95 percent carbon by weight, with a
smattering of hydrogen and oxygen atoms to keep them soluble
during manufacturing. They are manufactured in a 20-step
process similar to the way many drugs are synthesized from
small molecules in closed reactors. They are then suspended in
toluene gas and spun cast onto the gold surface.
Professor Tour said that he had not sought any patents on the
work because he believed it would take at least a generation
to overcome the many hurdles to molecular manufacturing using
the technology Rice has developed.
"The patents would have expired long before you could have
build a useful business," Professor Tour said.
Professor Tour has five graduate students working on the
research. He said that the scanning electron microscope
imaging necessary to capture the data is managed by his
co-author on the Nano Letters paper, Kevin F. Kelly, an
assistant professor of electrical and computer engineering,
and two other graduate students.
The original research was financed by Zyvex, a nanotechnology
company based in Richardson, Tex., the Welch Foundation and
the National Science Foundation. Professor Tour has recently
received an additional research grand from Honda of Japan.
Copyright 2005 The New York Times Company
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