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A Molecular Model of Nanogear
Nanoworld - Get to the very, very small world
" . . . Ultimately - in the great future - we can arrange the atoms the
way we want; the very atoms, all the way down! What would happen if we could
arrange the atoms one by one the way we want them."
--- Richard P. Feynman
On 29 Dec. 1959, the late Nobel laureate, physicist
Richard Feynman gave
a famous speech - "There's
Plenty of Room at the Bottom" - at the annual
meeting of the American Physical Society at the California Institute of Technology.
That was the first time the new idea of the "rearranging the atoms" came
out and since then the new era of the "Nanotechnology" has been started.
Feynman admired the "marvelous
biological system". He said: "The biological example of writing information on a small scale has
inspired me to think of something that should be possible . . .
A biology system can be exceedingly small. Many of the
cells are very tiny, but they are very active, they manufacture various substances; they
walk around; they wiggle; and they do all kinds of marvelous things - all on a very small
scale. Also, they store information.
Consider the possibility that we too can make a thing
very small which does what we want - that we can manufactureb an object that maneuvers at
that level!"
As an excellent physicist (He won the Nobel prize for
his work on quantum electrodynamics) , Feynman concluded that:
"To do things on an atomic level, is ultimately
developed - a development which I think cannot be avoided."
"The principle of physics, as far as I can see, do
not speak against ther possibility of maneuvering things atom by atom. it is not an
attempt to violate any law; it is something, in principle, that can be done; but in
practice, it has not been done because we are too big."
After Feynman's pioneer speech, nearly four decades have past. Eventually this
"great future " is coming. The molecular nanotechnology Train is emerging from the horizon.
All of us are interested in the new field of nanotechnology, because it's
based on a competely new strategy of making products, from more poweeful, cheap
spacecraft, supercomputer, cars, to almost all the industrial products. It will bring
major scientifc and practical breakthroughs. This will be another industry revolution in
the new millennium.
"Bottom-up" and "Top-down"
manufacturing
strategies
Today's manufacturing methods are very much of a "top-down" or "bulk-shaping" strategy. Large quantities of raw materials are used for cleaning, cutting, melting, refineing . . . more and more finely processed. It produced huge wastes and destructions of lands and natural sources.
Is it possible to take a completely new strategy, the
"bottom-up" manufacturing.
The products will be built up atom by atom, molecule by
molecule. Every atom will be arranged in the right place to reach the finest designs. This
is the so called "Nanotechnology" or "Molecular Nanotechnology"..
At the atomic level, Coal and Diamonds
are both made by carbon atoms.
Because the arrangement of atoms were different, they
became different materrials and with a big differnce in their values.
If we rearrange the atoms in coal, we will be able to make
diamonds very cheaply.
If we rearrange the atoms in air and water, we will be
able to make many many organic chemicals, even foods.
Nanotechnology has 3 requirements:
(A) Accuracy at the atom level - Making products with almost every atom in
the right place.
(B) Making the products' structures consistent with the laws of physics
and chamistry.
(C) Inexpensive cost.
To put every atom into the right place needs the devices of positional control at the atom level.
To keep the cost down needs a self replication
manufacturing system. Once you have built up a small basic unit at the atom level. It will
self replication to grow into the final large product.
These wonderful characters have been demonstrated by the biological systems including every bit of our own bodies. Is it possible that we will be able to do so in the next 50 - 100 years? Why we say that this fantastic nanotechnology train is emerging on the horizon?
From Today's Microtechnology to
Tomorrow's Nanotechnology
We would examine some progress that has been made in recent years towards the great goals of nanotechnology.
Pushing atoms and molecules around
Nanorobotic is an emerging field that deals with the
controlled manupulation of atoms and molecules. The size of an atom is at the 0.1 nm
range. To go down to this size of manipulation, certainly we need the microscopic tools.
STM (Scanning Tunelling Microscope) was a Nobel Prize winning invention by Binning and Rohrer at IBM Zurich Laboratory in the early 1980s. It allows us to manipulate subject and to see the result simultaniously at the atom level.
In 1989, the IBM scientist used a Scanning Tuneling Microscope (STM) pushed individual xenon atoms into the right positions and spelling out the letters I-B-M.
Today, various instruments analogous to the STM have been built.
Some commen instruments are: the AFM (Atomic Force Microscope), LFM (Lateral Force
Microscopy), STM (Scanning Thermal Microscopy), MFM (Magnetic Force Microscopy), SCM
(Scanning Capacitance Microscopy), EFM (Electric Force Microscopy), MRFM (Magnetic
Resonance Force Microscopy) etc.
All of these instruments are collectively called SPMs (Scanning Probe
Microscopy).
Since then scientists worldwide have been using these instrument to measure, monitor and even start to maniplulate atoms and molecules. They are able to push and pull, picking and placing various atoms and molecules on various platforms into precise positions.
IBM scientists have precisely positioned xenon atoms on nickel, iron atomes on copper, platium atoms on platinum and carbon monoxide molecules on platinum. In addition to these experiments at very low temperature(4K) and ultra high vacuum, they were able to reach successful room-temperature manipulation of atoms and molecules.
The IBM scientists even built up an abacus with individual molecules as beads with a diameter of <1nm. this world's smallest abacus has the stable rows of 10 soccerball-like C60 molecules. They were arranged along steps just one atom high on a copper surface. These steps act as "rails". Individual moleculea were the pushed back and forth in a precisely controlled way by the STM tip, and to count from 0 to 10.
Scientists at the University of Southern California have pushed gold
nanoparticles on a mica substrate at room temperature and in ambient air, to form the
letters of U-S-C.
And there are many successful examples in other laboratories around the
world.
Nanomanipulation with SPMs is a promising field, despite it being
clearly in its infancy. SPM-based assembly methods face a majot scale-up challenge.
Building complex structures one atom at a time is very time consuming. The massive
production will need the exploration of new programming or other means. Another challenge
is how to exploiting self-assembly.
The true nanorobots shaouls be the devices with overal diimensions in the
nanometer range and capable of sensing, thinking and acting.
Assembler Construction at Zyvex
Zyvex, the first molecular nanotechnology development
company was established in 1997 in Richardson, Texas. It takes the mission of developing
the first assembler.
To build the components essential to the operation of
an assembler, several strategies have been proposed, including protein engineering, SPM
placement of building blocks via antibody grippers, and ambient or vacuum placement of
surface bonded building blocks of individual atoms.
Besides the static three dimensional strucutres, the
construction of tight, non-reactive sliding interfaces to make up bearings, actuators and
other artculating components are also been considered.
To produce interfaces where the space between parts is
measured in 1/10 angstrom, it seems necessary to continuously add and remove small
interface joiners or spacers during the construction process, and to fit intermediate
parts into holes and bond them using these joiners.
At present time, they are working on the construction of a
double tripod positional device by SPM based mechanosynthesis, and making progress.
Machine Phase Fullerene Nanotechnology
Prof. Richard E. Smalley at Rice University shared the 1996 Nobel prize in Chemistry with his collaborators Robert F. Curl and harold W. Kroto for their 1985 discovery of fullerenes, a new crystalline form of carbon, C60.
NASA scientists are interested in developing advanced materials for the
aerospace vehicles.
They have carried out computational simulation studies of fullerenes.
Based on their own study and the computation and experiment performed
elsewhere, recently Al Globus et al. at NASA Ames Research Center suggested that a
nanotechnology based on machine phase functionalizeed fullerenes may be relatively
accessible and possess great potential for aerospace applications.
This fullerene nanotechnology might use carbon nanotubes and related
components as the building blocks of molecular machines; many studies have shown that the
carbon nanotubes are extremely strong and flexible.
They used molecular dynamics to study the properties of carbon
nanotube based gears and gear/shaft configulations and showed their excellent
qqualities.
A number of other components such as hinges, springs, universal joints and
other systems also have been designed.
Conceptually, Al Globus and his colleagues envisage a future fullerene nanotechnology manufacturing system, in which small molecular components are generated synthetically in bulk and fed to the replicating "swarm" - a programmable replicator.. The swam assembles swarm edges and nodes from the molecular components thereby growing and eventually dividing. Large numbers of such machines could conceivably create a material able to react to the environment and repair itself.
DNA nanotechnology
The biological system is always looked by the
nanotechnologists as the example of the future nanomachines.
Prof. nadrian C. Seeman at New York University is the
winner of the 1995 Feynman Prize in Nanotechnology.
(The Nobel laureate Feynman died in 1988. The Freynman
Prize is sponsored by the Foresight Institute, and is given biennially for the scientific
work that msot advanced the development of molecular nanotechnology.).
Seeman's group work on the DNA nanotechnology. They construct molecular building blocks from unusual DNA motifs. They used the stable branched DNA molecules to construct a covalently closed DNA molecule whose helix axes have the connectivity of a cube or a truncated octahedron.
They also have used DNA to make four topological
species - circle, treefoil knots of both signs and a figure-8 knot.
They made the RNA knots as well and discovered the
existance of a RNA topoisomerase.
DNA-based topological control has also led to the
construction of Borromean Rings, which could be used in DNA-based computing applications.
In the DNA constructions, the lack of a rigid
molecule was a key feature. Howeveer recently they have used the antiparallel DNA double
crossover molecules to incorporate in DNA assembles that make use of this rigidity to
achieve control on the geometrical level as well as on the topological leevel.
Super-Nanocomputer
For the past 40 years, the electronic computers have grown
more powerful as their transistors have been minimized. However the laws of quantum
mechanics and the limitations of fabrication techniques soon will prevent further
reduction in the minimun size of today's semiconductor transistors. Once the transistor's
design shrink to <0.1 micrometers, the devices no longer will function usefully.
New approaches to build computers are necessary.
Ongoing research use mathematical and computer modeling have shown that electronic nanodevices are possible. A Nanocomputer could be many orders of magnitude more powerful than today's microcomputers.
The future nanocomputer might be built upon experince
with microcomputers, but take advantage of the very same quantum effects that limit
current micro-scale transistors. The ultimate choice of technologies and designs will
depnd on the device speed, power dissipation, reliability and ease of fabrication.
It seems likely that along the development of
moleculae-scale manipulation tools, the first practical nanoelectronic circuits might
emerge in the first decade of the 21st century.
The future nanocomputers will largely transform our
electronic computing and the technological infrastructure.
It is amazing to see that the multidisciplinary
nature of nanotechnology draws on so many talented scientists from different fields, from
physics, chemistry, biology, computer science . . .
It is difficult to predict from which traditional
discipline will come the key breakthrough necessary to construct these future
nanotechnological products.
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