Nanophase und morgen wird dieser Bericht bei den Amis veröfentlicht

Business & Technology 7/3/00


The next big thing is
small
Machines the size of molecules are
creating the next industrial revolution

By Phillip J. Longman

Several months ago, a group of scientists from the
University of Michigan`s Center for Biologic
Nanotechnology traveled to the U.S. Army`s
Dugway Proving Ground in Utah. The purpose of
their visit: to demonstrate the power of
"nano-bombs." These munitions don`t exactly go
"Kaboom!" They`re molecular-size droplets, roughly
1/5000 the head of a pin, designed to blow up
various microscopic enemies of mankind, including
the spores containing the deadly biological warfare
agent anthrax.

The military`s interest in nano-bombs is obvious. In
the test, the devices achieved a remarkable 100
percent success rate, proving their unrivaled
effectiveness as a potential defense against anthrax
attacks. Yet their civilian applications are also
staggering. For example, just by adjusting the
bombs` ratio of soybean oil, solvents, detergents,
and water, researchers can program them to kill the
bugs that cause influenza and herpes. Indeed, the
Michigan team is now making new, smarter
nano-bombs so selective that they can attack E.
coli, salmonella, or listeria before they can reach
the intestine.

If you`re a fan of science fiction, you`ve no doubt
encountered the term nanotechnology. Over the
past 20 years, scores of novels and movies have
explored the implications of mankind`s learning to
build devices the size of molecules. In a 1999
episode of The X-Files titled "S. R. 819,"
nanotechnology even entered the banal world of
Washington trade politics, with various nefarious
forces conspiring to pass a Senate resolution that
would permit the export of lethal "nanites" to rogue
nations.

Yet over the past year or so, a series of
breakthroughs have transformed nanotech from
sci-fi fantasy into a real-world, applied science, and,
in the process, inspired huge investments by
business, academia, and government. In industries
as diverse as health care, computers, chemicals,
and aerospace, nanotech is overhauling production
techniques, resulting in new and improved
products–some of which may already be in your
home or workplace.

Silicon fingers. Meanwhile, nearly every week,
corporate and academic labs report advances in
nanotech with broad commercial and medical
implications. In April, for example, IBM announced
it had figured out a way to use DNA to power a
primitive robot with working, silicon fingers 1/50 as
thick as human hair. Within a decade or so, such
devices may be able to track down and destroy
cancer cells. Over at Cornell University, researchers
have developed a molecular-size motor, built out of
a combination of organic and inorganic
components, that some dub nanotech`s "Model T."
In tests announced last September, the machine`s
rotor spun for 40 minutes at 3 to 4 revolutions per
second. When further developed, such motors will
be able to pump fluids, open and close valves, and
power a wide range of nanoscale devices.

These inventions and products are just the
beginning of what many observers predict will be a
new industrial revolution fostered by man`s growing
prowess at manipulating matter one atom, or
molecule, at a time. (Nanotech takes its name from
the nanometer, a unit of measurement just one
billionth of a meter long.) "Because of nanotech, we
will see more change in our civilization in the next
30 years than we did during all of the 20th century,"
says Mihail Roco, a senior adviser for
nanotechnology at the National Science
Foundation.

In a speech at Caltech last January, in which he
called for a $497 million National Nanotechnology
Initiative, President Clinton recounted some of the
wonders that he and his science advisers believe
are in store. "Imagine the possibilities," Clinton
gushed. "Materials with 10 times the strength of
steel and only a small fraction of the weight.
Shrinking all the information housed at the Library
of Congress into a device the size of a sugar cube.
Or detecting cancerous tumors when they are only
a few cells in size."

To build such objects, engineers are employing a
wide range of techniques, borrowed from
bioengineering, chemistry, and molecular
engineering. Such feats include imitating the
workings of the body, where DNA not only
programs cells to replicate themselves but also
instructs them how to assemble individual
molecules into new materials, such as hair or milk.
In other words, many nanotech structures build
themselves.

Atom by atom. The inspiration for nanotech goes
back to a 1959 speech by the late physicist
Richard Feynman, titled "There`s Plenty of Room at
the Bottom." Feynman, then a professor at the
California Institute of Technology, proposed a novel
concept to his colleagues. Starting in the Stone
Age, all human technology, from sharpening
arrowheads to etching silicon chips, has involved
whittling or fusing billions of atoms at a time into
useful forms. But what if we were to take another
approach, Feynman asked, by starting with
individual molecules or even atoms, and assembling
them one by one to meet our needs? "The
principles of physics, as far as I can see, do not
speak against the possibility of maneuvering things
atom by atom," Feynman noted.

Four decades later, Chad Mirkin, a chemistry
professor at Northwestern University`s $34 million
nanotech center, used a nanoscale device to etch
most of Feynman`s speech onto a surface the size
of about 10 tobacco smoke particles–a feat that
Feynman would no doubt have taken as vindication.
But the course science took to achieve such levels
of finesse has not always been straightforward. Nor
has it been lacking in controversy.

Indeed, some scientists are alarmed by
nanotechnology`s rapid progress. Last April, Bill
Joy, the chief scientist at Sun Microsystems,
created a stir when he published an essay in Wired
magazine warning that in the wrong hands,
nanotech could be more destructive than nuclear
weapons. Influenced by the work of Eric Drexler, an
early and controversial nanotechnology theoretician,
Joy predicted that trillions of self-replicating
nanorobots could one day spin out of control,
literally reducing the earth`s entire biomass to "gray
goo." Joy foresees bans on some kinds of
research, along the lines of prohibitions against
biological or chemical warfare, but admits he is not
sure how to institute them. "I don`t think there is a
technological solution," he says. "I think it has to
be ethical and political."

Most researchers in the field don`t share Joy`s
concern. "We are compelled to keep going. It is
just so cool," says Paul Alivisatos, professor of
chemistry at the University of California-Berkeley.
"We are knocking on the door of creating new living
things, new hybrids of robotics and biology. Some
may be pretty scary, but we have to keep going."

The early payoffs have already arrived. Computer
makers, for example, use nanotechnology to build
"read heads," a key component in the
$34-billion-a-year hard disk drive market, which
vastly improve the speed at which computers can
scan data. Another familiar product, Dr. Scholl`s
brand antifungal spray, contains nano-scale zinc
oxide particles–produced by a company called
Nanophase Technologies–that make aerosol cans
less likely to clog. Nanoparticles also help make
car and floor waxes that are harder and more
durable and eyeglasses that are less likely to
scratch. As these examples show, one huge
advantage of nanotech is its ability to create
materials with novel properties not found in nature
or obtainable through conventional chemistry.

What accounts for the sudden acceleration of
nanotechnology? A key breakthrough came in
1990, when researchers at IBM`s Almaden
Research Center succeeded in rearranging
individual atoms at will. Using a device known as a
scanning probe microscope, the team slowly moved
35 atoms to spell the three-letter IBM logo, thus
proving Feynman right. The entire logo was less
than three nanometers.

Soon, scientists were not only manipulating
individual atoms but "spray painting" with them as
well. Using a tool known as a molecular beam
epitaxy, scientists have learned to create ultrafine
films of specialized crystals, built up one molecular
layer at a time. This is the technology used today
to build read-head components for computer hard
drives.

One quality of such films, which are known as giant
magnetoresistant materials, or GMRs, is that their
electrical resistance changes drastically in the
presence of a magnetic field. Because of this
sensitivity, hard disk drives that use GMRs can
read very tightly packed data and do so with
extreme speed. In a few years, scientists are
expected to produce memory chips built out of
GMR material that can preserve 100 megabits of
data without using electricity. Eventually, such
chips may become so powerful that they will simply
replace hard drives, thereby vastly increasing the
speed at which computers can retrieve data.

Natural motion. The next stage in the
development of nanotechnology borrows a page
from nature. Building a supercomputer no bigger
than a speck of dust might seem an impossible
task, until one realizes that evolution solved such
problems more than a billion years ago. Living cells
contain all sorts of nanoscale motors made of
proteins that perform myriad mechanical and
chemical functions, from muscle contraction to
photosynthesis. In some instances, such motors
may be re-engineered, or imitated, to produce
products and processes useful to humans.

Animals such as the abalone, for example, have
cellular motors that combine the crumbly
substance found in schoolroom chalk with a
"mortar" of proteins and carbohydrates to create
elaborate, nano-structured shells so strong they
can`t be shattered by a hammer. Using a
combination of biotechnology and molecular
engineering, humans are now on the verge of being
able to replicate or adapt such motors to suit their
own purposes.

How are these biologically inspired machines
constructed? Often, they construct themselves,
manifesting a phenomenon of nature known as
self-assembly. The macromolecules of such
biological machines have exactly the right shape
and chemical binding preferences to ensure that
when they combine they will snap together in
predesigned ways. For example, the two strands
that make up DNA`s double helix match each other
exactly, which means that if they are separated in a
complex chemical mixture, they are still able to find
each other easily.

This phenomenon is potentially very useful for
fabricating nanoscale products. For instance, last
year, a team of German scientists attached building
materials such as gold spheres to individual strands
of DNA and then watched as the strands found
each other and bound together the components
they carried, creating a wholly new material.

Similarly, the 1996 Nobel Prize in chemistry went
to a team of scientists for their work with
"nanotubes"–a formation of self-assembling carbon
atoms about 1/50,000 the width of a human hair.
Scientists expect that when they succeed in
weaving nanotubes into larger strands, the resulting
material will be 100 times stronger than steel,
conduct electricity better than copper, and conduct
heat better than diamond. Membranes of such
fibers should lead to rechargeable batteries many
times stronger, and smaller, than today`s.

Last March, a team of IBM scientists announced
that they had used self-assembly principles to
create a new class of magnetic materials that could
one day allow computer hard disks and other
data-storage systems to store more than 100 times
more data than today`s products. Specifically, the
researchers discovered certain chemical reactions
that cause tiny magnetic particles, each uniformly
containing only a few thousand atoms, to
self-assemble into well-ordered arrays, with each
particle separated from its neighbors by the same
preset distance.

Other scientists have discovered important new
self-assembling entities by accident. In 1996,
Samuel Stupp, a professor at Northwestern
University, was in his lab trying to develop new
forms of polymer when he inadvertently came upon
"nanomushrooms." "It was such a beautiful thing,"
recalls Stupp. "I saw the potential right away." The
molecules he had been experimenting with had
spontaneously grouped themselves into
supramolecular clusters shaped like mushrooms.
Soon afterward, Stupp discovered, again
accidentally, that he could easily program these
supramolecules to form film that behaves like
Scotch tape.

Meanwhile, researchers at UCLA and
Hewlett-Packard have laid the groundwork for the
world`s first molecular computer. Eventually, the
researchers hope to build memory chips smaller
than a bacterium. Such an achievement is essential
if computing power is to continue doubling every 18
to 24 months, as it has for the past four decades.
This is because the more densely packed the
transistors on a chip become, the faster it can
process, and we are approaching the natural limit to
how small transistors can be fabricated out of
silicon.

Future phenomena. Where will it all end? Many
futurists have speculated that nanotech will
fundamentally change the human condition over the
next generation. Swarms of programmable
particles, sometimes referred to as "utility fog," will
assemble themselves on command. The result
could be a bottle of young wine molecularly
engineered to taste as if it had aged for decades, or
a faithful biomechanical dog with an on/off switch.

Meanwhile, new, superstrong, lightweight
nanomaterials could make space travel cheap and
easy and maybe even worth the bother, if, as some
authors predict, nanotech can be used to create an
Earth-like atmosphere on Mars. And space
colonization could well be necessary if the new
science of "nanomedicine" extends life indefinitely,
manufacturing new cells, molecule by molecule,
whenever old cells wear out. It all seems hard to
imagine; yet nanotech has already produced
enough small wonders to make such big ideas
seem plausible, if not alarming–at least to the high
priests of science.

With Janet Rae-Dupree and Charles W. Petit