Document Sample
electronics Powered By Docstoc

K.V.SANDEEP GUPTA                  M.V.SATEESH
B.TECH (II YEAR)                  B.TECH( II YEAR)

Y.ANUSHA                           M.SRI RAMA
B.TECH (II YEAR)                  B.TECH( II YEAR)


Y.ANUSHA (#41),
KAKINADA-533003, A.P.
CONTACT NO-9885502319.
       Discoveries and developments in science and technology are at the core of
human endeavour. Recently, there have been some significant advances in the
fabrication and demonstration of individual molecular electronic wires and diode
switches. This paper shows how these demonstrated molecular devices might be
combined to design molecular-scale electronic digital computer logic. These designs
correspond to conductive monomolecular circuit structures that would be one million
times smaller in area than the corresponding micron-scale digital logic circuits
fabricated on conventional solid-state semiconductor computer chips. At the very
least, these molecular circuit designs constitute an exploration of the ultimate limits of
electronic computer circuit miniaturization. Nonetheless, molecular diode switches
and diode-based logic are likely to be important components of future molecular
electronic digital circuits, if only because they demand many fewer interconnects and,
consequently, should make such ultra-dense circuitry much easier to design and to

       The World is on the brink of a technological revolution beyond any human
experience. It has the potential to bring wealth, health and education to every person
on the planet. And it will be able to do this without consuming natural resources or
spewing pollution into the environment. Nanotechnology is about building things
atom by atom. The intellectual drive toward nanoworld has been the initial underlying
reason for the current focus on nanotechnology. Nanoscale science and engineering
will allow us to reach beyond our natural size limitation and work directly at the
building blocks of matter where all properties of matter are defined and can be
changed. Discovery of novel material structures with fundamentally new properties,
new tools demonstrating nanoscale phenomena, new molecular assembling and
techniques yielding control of structures at the nanoscale, are leading to a unified set
of general principles for a variety of disciplines and areas of application.
       Manufactured products are made from atoms. The properties of those products
depend on how those atoms are arranged. If we rearrange the atoms in coal we can
make diamond. If we rearrange the atoms in sand (and add a few other trace elements)
we can make computer chips. If we rearrange the atoms in dirt, water and air we can
make potatoes.
       Miniaturization. It’s a word we’ve become accustomed to over the last few
decades. We’ve heard that Computers that once took up whole rooms half a century
ago, can now easily fit on to a microchip that sits on the tip of your finger. But what if
you could go even much, much smaller than that? . Their field is called
       If you could see the parts of a nanomachine, you would see the individual
atoms. These atoms are held together by their chemical bonds. In theory, as long as
the atoms are never stressed beyond their bond strength, this device will never wear
       How about a microscopic computer billions of times faster than today’s fastest
electronic brains? They could control nanomachines that could patrol our bodies like
an artificial immune system.
       Ultimately, with atomic precision, food could be synthesized from raw atoms
with the same nano assembler that just made a new
camera.Imagine being able to cure cancer by drinking a
medicine stirred into your favorite fruit juice.
       Imagine a supercomputer no bigger than a human
cell.Imagine a four-person, surface-to-orbit spacecraft no
larger or more expensive than the family car.
       Machines that can repair cells on a molecular scale, that perhaps through
manipulating DNA, could stop or reverse the aging process.
        Now imagine this. You make a microscopic tool from a synthetic protein
molecule. You place it on the miniscule tip of a scanning tunneling microscope. Now
you can grab a specific molecule out of a chemical solution, and place it in exactly the
right spot on a nanomachines you're building
        Most people think the pace of technological change has increased over the last
few decades, but it really hasn’t. We’ve just spread things out and made it seem that
way. We don’t have breakthrough developments anymore. The developments that
we’ve seen over the last three decades pale in comparison to those of the early
twentieth century when the telephone, automobiles, airplanes, television and anti-
biotics burst onto the seen for the first time. Today’s seemingly goal-less change has
made many people believe that we are changing for no other reason than for change
        In the future, nanotechnology will be able to snap together the fundamental
building blocks of nature easily, inexpensively and in almost any arrangement that we
desire. This will be essential if we are to continue the revolution in computer
hardware beyond about the next decade, and will also let us fabricate an entire new
generation of products that are cleaner, stronger, lighter, and more precise.
        It’s worth pointing out that the word “nanotechnology” has become very
popular and is used to describe many types of research where the characteristic
dimensions are less than about 1,000 nanometers. For example, continued
improvements in lithography have resulted in line widths that are less than one
micron: this work is often called “nanotechnology.”
What is Nanotechnology?
        What would we build with the individual atoms? Well... everything. A nano
machine would look remarkably like a
standard machine ...with gears, bearings,
struts and the like. But each of those
components would actually be made out
of individual atoms. That means each
part    would   be   incredibly    small.
Remember, ten atoms, side-by-side are
still a thousand million times smaller
than a meter. That means a complicated machine that takes up almost no space.
        This is an artist's conception of a nanomachine. This particular design is a
microscopic robot that could patrol the human body -- just like an artificial immune
system. Nanomachines would look remarkably like standard machines with gears,
bearings, struts, tubes, platforms, hinges, conveyor belts, robot arms and electric
motors.... Except that the components would be microscopic. They would be made
from individual atoms.
         Electronics is fueled by miniaturization. Working smaller has led to the tools
capable of manipulating individual atoms like the proteins in a potato manipulate the
atoms of soil, air and water to make copies of it.
         The shotgun marriage of chemistry and engineering called “Nanotechnology”
is ushering in the era of self-replicating machinery and self-assembling consumer
goods made from cheap raw atoms Nanotechnology is molecular manufacturing or,
more simply, building things one atom or molecule at a time with programmed
nanoscopic robot arms.

                         When it’s unclear from the context whether we’re using the
                  specific definition of “nanotechnology” (given here) or the broader
                  and more inclusive definition (often used in the literature), we’ll use
                  the terms “molecular nanotechnology” or “molecular manufacturing”
                  Whatever we call it, it should let us
·   Get essentially every atom in the right place.
·   Make almost any structure consistent
    with the laws of physics and chemistry
    that we can specify in atomic detail.
         Humanity will be faced with an
industrial, monetary and social quake as a
result    of   molecular     manufacturing
programmed self-assembly. In the near
future, a team of scientists will succeed in
constructing the first nano-sized robot
capable of self-replication. Within a few short years, and five billion trillion nano-
robots later, virtually all present industrial processes will be obsolete as well as our
contemporary concept of labor. Consumer goods will become plentiful, inexpensive,
smart, and durable. Medicine will take a quantum leap forward. Space travel and
colonization will become safe and affordable. For these and other reasons, global life
styles will change radically, drastically impacting human behavior.
Economic Changes to Come:
       Like the buggy whip manufacturer at the dawn of the automobile,
contemporary manufacturing will become obsolete. The first day a nano sized self-
reproducing robot (and its trillions of offspring) arrives, every contemporary
manufacturing process and all the required laborers will no longer be necessary. So,
industrialists, manufacturers, beware! Long-term planning takes on a whole new
meaning during an industrial revolution!
       What jobs can we imagine will be necessary in a nanotechnology future?
Well, there is one profession with a very bright future indeed! Systems Programming.
       In the nanotechnology world, almost everything will be made of smart
materials run by oodles of microscopic computers that will need software. Everything,
did I mention everything, will depend on software. You, the programmer, will be in
bigger demand than ever imagined today. This is truly one of the few professions that
will need to be “paid”, but with what?
       Other professions will continue to be in demand. Nanotechnology research
will continue and advances in the sciences will create more research opportunities.
Rebuilding the ecology will call for geologists, archeologists and ecologists alike.
Creativity and self-actualization will abound. Art, music, literature, indeed all the
humanities, will thrive. Those who help others can also count on some continued
employment. The fields of psychiatry, psychology, and sociology will have whole
new applications.
       If history is a guide, more opportunities will exist in a nanotechnology
future—due to the abundance of applications and inventions yet to be imagined.
Technical feasibilities include:
·     Self-assembling consumer goods
·     Computers billions of times faster
·     Extremely novel inventions (impossible today)
·     Safe and affordable space travel
·     Medical Nano... virtual end to illness, aging, death
·     No more pollution and automatic cleanup of already existing pollution
·     Molecular food syntheses... end of famine and starvation
·     Access to a superior education for every child on Earth
·     Reintroduction of many extinct plants and animals
·     Terraforming here and the Solar System
Why is Nanotechnology Happening?
       Biologists are a good audience to present Molecular Nanotechnology (MNT)
as they are intimately familiar with analogs of the tools of proposed MNT
programmable self-replicating machinery, possible with atomic precision
construction. Biology is after all the undisputable proof that systems exist doing the
“Drexlerian thing” (or Drexler as seen in his own mirror proves Drexler). A seed has a
DNA program instructing atomic and molecular manipulators—proteins, initially
running on stored energy—scavenging atoms in the local environment to make copies
of proteins and other devices to collect energy and power up for larger output... and
eventually make more nanites... ah, make that seeds... along the way, if we
reprogrammed that DNA to divert some of the energy to make apples laced with
cinnamon or grow computers, then we get microwaveable deserts or computers that
grow on trees. If a student of this discipline is less than competent, at best we may get
bad tasting deserts and computers that don’t work.
       Computer people are the best novel audiences. They are intimately familiar
with the concept of replicating quanta. The step towards treating atoms like bits of
information is no distance at all. They see their own hardware driven by economic
frenzy in an exponential dive toward the atomic realm... and beyond. They don’t need
the chemist or biologist to hit nanotechnology, the chip manufacturer will develop
manipulation at this resolution regardless of any prejudice and a little math shows
how very soon.
       Chemists are another story! Having so much invested in super clever
synthesis of structures using Shake and Bake technology, when presented with the
idea of placing an atom on a hot spot of a synthetic molecule the size of a 747...
chemists flinch with an involuntary negative reaction difficult to quench with rational.
To increase offense by saying something like, “This shotgun marriage of chemistry
and engineering...” is a deliberate push over the edge.
        Several major scientific disciplines are running on a headlong collision
course with nanotechnology (the precise manipulation of matter on an atomic scale).
Very clever chemists, with great difficulty, synthesize larger and larger molecules that
perform more and more complicated tasks. Dr. Ralph Merkle suggests that
chemistry is like building objects with a loose dangling string. Nonetheless, chemists’
control over matter at the nanometer level continually increases in sophistication.
        Biologists have faced the daunting task of making sense out of a bewildering
array of preexisting “nano” machines that took some 3.5 billion years of natural
selection to evolve. All life on earth falls into this category. To paraphrase K. Eric
    “If you want to see a nanotechnology machine, look in the mirror.”
        Imagine trying to figure out a three dimensional puzzle with trillions (not
billions) and trillions of interactive parts! Genetics, the self-replicating blueprint of all
biological life, has been a focus in research resulting in the human manipulation of
these “nano” machines. Biologists are constantly discovering and modifying these
pre-existing molecular machines and advancing greatly in the development of
        Even if advancements in these two disciplines suddenly grind to a halt, the
drive to precision (brute force) atomic chemistry, or nanotechnology, could not be
stopped. Enter the computer or more specifically, the microchip manufacturer...
        The Moore’s law holds good today and as per his law every 18 months or so,
the size of wires and transistors is cut by 50% while the speed of the chip is doubled.
The wires are already a fraction of a micron small. How long can you keep cutting the
size of components in half and expect it to function? As the things turns out, not much
longer this process of cutting wire would exist. Soon the wires will become so thin
and packed so tight that an effect of Quantum Mechanics will come into play.
Namely, tunneling. The electrons tunnel through insulating barriers too thin to keep
them contained. If one builds a chip with wires so small and insulators so thin,
electrons start wholesale tunneling, or shorting out, rendering the device totally
       Soon chip designers will be forced to switch to an old-fashioned mechanical
calculator concept, but with a nouveau twist. If you can build these mechanical parts
one atom at a time, they can be thousands of times smaller and millions of times faster
than existing transistors. The competition for faster chips is fierce and the profit at
stake immense. It’s a freight train running downhill that cannot be stopped. And that
train’s destination is nanotechnology!
       The widespread potential of nanotechnology to improve medicine,
manufacturing, the environment, and our general
material abundance makes it a situation where
incremental efforts make more sense as an
exception, rather than a rule. I think we’ve been
overly dependent on the incremental approach, and have wasted a lot of time, money,
effort, life, and opportunity as a result. It’s hard to get people to prepare for a
breakthrough technology when it’s coming slowly and there’s no deliberate effort to
achieve it. Most people think the pace of technological change has increased over the
last few decades, but it really hasn’t. We’ve just spread things out and made it seem
that way. We don’t have breakthrough developments anymore. The developments that
we’ve seen over the last three decades pale in comparison to those of the early
twentieth century when the telephone, automobiles, airplanes, television and anti-
biotics burst onto the seen for the first time. Today’s seemingly goal-less change has
made many people believe that we are changing for no other reason than for change
sake. As a result, people are getting burnt out on the idea of technological progress.
They’re paying less attention, and that’s when you have the potential for a surprise
that no ones prepared for. The goal of developing molecular nanotechnology is
something that must be pursued in a “direct” way that gets the publics attention.
Nanodot Lasers:
       Make particles of semiconductors small enough—just a few nanometers
across—and they glow in a dazzling range of colors. These nano particles are known
as quantum dots, because quantum effects tune the color of the glow to the size of
the particle—a phenomenon that scientists have seized upon to make exquisitely
sensitive biomedical assays. In theory, these tiny glowing particles could also be a
boon for optical networking by providing lasers and amplifiers that work in a wide
range of frequencies. But for over a decade experts have been trying to fashion
quantum-dot lasers, with little
                                        Three films, each made of different-sized
                                        cadmium selenide quantum dots. A film made of
        If the scientists are right,
                                        dots 1.2 nanometers in diameter glows green,
the future of quantum dots in
                                        while a film of 2.1-nanometer dots glows
expanding the possibilities of
                                        orange. (Image courtesy of Victor Kilmov)
optical communication could be
bright, indeed.
When will Nanotechnology arrive?
        The goal of nanotechnologists is to produce the first nano-sized robot, a
machine capable of reproducing itself. Why is this important? Because the things we
want the robots to build are made of trillions and trillions of atoms. One nano-
assembler, working atom by atom, would be rather slow. Huge numbers of nano-
assemblers all working together can build useful products quickly.
Applications of Nanotechnology:
        Nanomachines probably have the most potential in medicine, acting as
miniature surgeons that can repair individual cells. If such machines can be designed
to self-replicate, it would only be necessary to build one such machine and implant it
in the body where it can do its repair work.
        In possible difficulties with this application, aside from the actual
manufacturing and self-replicating issues, there is the issue of how the human body
would take to such foreign objects. A possible solution could be to somehow "code"
the machines so that the cells of the immune system mistake them for a cell in the
body, as the cells of the immune system respond to a type of "code" on the surface of
cells to distinguish foreign objects.
        Nanotechnology could be used in this way not only to heal diseases or injuries,
but to maintain health as well. Nanomachines could be used to detect problems in the
body as they start to occur and repair those problems. In effect, these nanomachines
could      function   as   a   more     efficient   immune   system   for   the   body.
        Nanomachines can also be incorporated into various materials to make those
materials respond to their environment, or to outside commands. Examples of such
materials would be "smart" fabrics that respond to the environment to become warmer
or cooler, or walls and furniture that can move or change shape on command.
        Nanomachines could also be used as tools in industry. Such tools could cut
apart or glue together material far more efficiently than anything large-scale that is
used today. Nanomachines could also repair cars, furniture, appliances, or almost
anything else quickly and efficiently. Or these objects could be designed with
nanomachines to repair themselves should the need arise. Life would be greatly
simplified by relieving people of the need to repair objects at home or at work.
        In computer science, nanotechnology has huge potential in building smaller
and smaller computers. Far greater amounts of information would be stored in the
same amount of space. This has enormous space-saving implications. Someday, all
the books in the world may be fit into the space of a square inch. Such efficient data
storage has great potential for business and scientific research in all fields. Such
microcomputers also have great potential for the entertainment industry. With such
great data storage capacity, extremely elaborate computer games and virtual reality
environments could be created. Life could become not only easier but more fun as
        It is easy to become overly optimistic when evaluating the potential of
nanotechnology. However, if even a few of the aforementioned predictions come true,
the standard of life would be elevated. The greatest current potential for
nanotechnology is data storage. However, as new manufacturing methods for
nanomachines become available, their potential will greatly grow. Only time will tell
what the future holds.
       Does this all seem fantastic? Well, it is theoretically possible. Many of the
tools for this new technology are already being developed in the fields of biology,
chemistry and electronics. Right now some 200 universities, corporations and
government labs around the world are engaged in nanotechnology research. Though
we have yet to have a nanotechnological breakthrough, the possibilities are endless.

       When it’s unclear from the context whether we’re using the specific definition
of “nanotechnology” (given here) or the broader and more inclusive definition (often
used in the literature), we’ll use the terms “molecular nanotechnology” or “molecular
       The anticipated payoff for mastering this technology is beyond any human
accomplishment thus far.
       We’ll have time to adapt, to weigh consequences, and to develop defenses and
counter-measures. Besides, even early nanotech should be very useful, especially for
biomedical and chemical research, and for of all kinds instrumentation. And
nanotechnology is not the only field that promises wonders in the coming decades.
There will be miracles enough to fill the years before nanotechnology really hits its
stride. But some of the more subtle dangers of nanotechnology such as the possibility
of altering memories should be delayed as well.

       Nanotechnology is a field which holds much promise in its future applications.
It has numerous possibilities in the fields of medicine, computer science,
entertainment, industry, and many others. One must beware of being overly
optimistic; however, with that in mind, the possibilities for improving life with
nanotechnology are many. Nanotubes have the potential to be extremely strong fibers,
stronger than anything yet discovered. Once reliable synthesis techniques for
buckytubes and other nanotubes are found, they can be used to produce a variety of
new materials.


       The material has been taken from Internet. The various sites are
www.zyvex.com, www.nano.org.uk, www.nanozine.com, and www.mitre.org

Shared By:
godavari phanidhar godavari phanidhar