NanoTechnology (Download Full Seminar Report)

[mechanical engineering]

ABSTRACT
A nanometer is one billionth of a meter. If you blew up a baseball to the size of the
earth, the atoms would become visible, about the size of grapes. Some 3- 4 atoms fit
lined up inside a nanometer. Nanotechnology is about building things atom by atom,
molecule by molecule. The trick is to be able to manipulate atoms individually, and
place them where you wish on a structure.
Nanotechnology uses well known physical properties of atoms and molecules to make
novel devices with extraordinary properties. The anticipated pay off for mastering this
technology is beyond any human accomplishment thus far.
Nature uses molecular machines to create life.Scientists from several fields including
chemistry, biology, physics, and electronics are driving towards the precise
manipulation of matter on the atomic scale. How do we get to nanotechnology Several
approaches seem feasible. Ultimately a combination may be the key.
The goal of early nanotechnology is to produce the first nano-sized robot arm capable
of manipulating atoms and molecules into a useful product or copies of itself.
Nanotechnology finds applications as nanotubes, in nanomedicine and so on.Soon you
have trillions of assemblers controlled by nano super computers working in parallel
assembling objects quickly.
Ultimately, with atomic precision, everything could be made. It's all a matter of
software.
CONTENTS
* INTRODUCTION
* NANOTECHNOLOGY
-AN INTERDISCIPLINARY SUBJECT
* BOTTOM-UP TECHNOLOGY
* NANOMACHINES
* FABRICATION
* STEWART PLATFORM
* VISUAL IMAGES IN NANO TECNOLOGY
* APPLICATIONS
* CHALLENGES
* ETHICAL ISSUES
* CONCLUSION
* BIBLIOGRAPHY
INTRODUCTION
A nanometer is one billionth of a meter. That's a thousand, million times smaller than a meter. If
you blew up a baseball to the size of the earth, the atoms would become visible, about the size of
grapes. Some 3- 4 atoms fit lined up inside a nanometer. Nanotechnology is about building things
atom-by-atom, molecule-by-molecule. The trick is to be able to manipulate atoms individually, and
place them where you wish on a structure. Thus nanotechnology can be defined as:
Thorough, inexpensive control of the structure of matter based on molecule-by-molecule
control of products and byproducts; the products and processes of molecular manufacturing.
LEARNING FROM NATURE
Technology-as-we-know-it is a product of industry, of manufacturing and chemical
engineering. Industry-as-we-know-it takes things from nature”ore from mountains, trees
from forests”and coerces them into forms that someone considers useful. Trees become
lumber, then houses. Mountains become rubble, then molten iron, then steel, then cars. Sand
becomes a purified gas, then silicon, and then chips. And so it goes. Each process is crude,
based on cutting, stirring, baking, spraying, etching, grinding, and the like.
Trees, though, are not crude: To make wood and leaves, they neither cut, grind, stir, bake,
spray, etch, nor grind. Instead, they gather solar energy using molecular electronic devices,
the photosynthetic reaction centers of chloroplasts. They use that energy to drive molecular
machines”active devices with moving parts of precise, molecular structure”which process
carbon dioxide and water into oxygen and molecular building blocks. They use other
molecular machines to join these molecular building blocks to form roots, trunks, branches,
twigs, solar collectors, and more molecular machinery. Every tree makes leaves, and each
leaf is more sophisticated than a spacecraft, more finely patterned than the latest chip from
Silicon Valley. They do all this without noise, heat, toxic fumes, or human labor, and they
consume pollutants as they go. Viewed this way, trees are high technology. Chips and
rockets aren't.
Trees give a hint of what molecular nanotechnology will be like, but nanotechnology won't
be biotechnology. Like biotechnology”or ordinary trees”molecular nanotechnology will
use molecular machinery, but unlike biotechnology, it will not rely on genetic meddling.
THE SCALE
We humans are huge creations with no direct experience of the molecular world, and this can
make nanotechnology hard to visualize, hence hard to understand. The nano in
nanotechnology comes from nanos, the Greek word for dwarf. In science, the prefix nanomeans
one-billionth of something, as in nanometer and nanosecond, which are typical units
of size and time in the world of molecular manufacturing. Lets try to visualize: you say,
"Shrink me!", and the world seems to expand.



NANOTECHNOLOGY-AS AN INTERDISCIPLINARY SUBJECT
Another feature of nanotechnology is that it is the one area of research and development that
is truly multidisciplinary. Research at the nanoscale is unified by the need to share
knowledge on tools and techniques, as well as information on the physics affecting atomic
and molecular interactions in this new realm. Materials scientists, mechanical and electronic
engineers and medical researchers are now forming teams with biologists, physicists and
chemists
BOTTOM-UP TECHNOLOGY
The two fundamentally different approaches to nanotechnology are graphically termed 'top
down' and 'bottom up'. 'Top-down' refers to making nanoscale structures by machining and
etching techniques, whereas 'bottom-up', or molecular nanotechnology, applies to building
organic and inorganic structures atom-by-atom, or molecule-by-molecule. Top-down or
bottom-up is a measure of the level of advancement of nanotechnology
NANOMACHINES
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.
In future we'll be able to snap together the fundamental building blocks of nature easily,
inexpensively and in most of the ways permitted by the laws of physics. 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.
TOP-DOWN BOTTOM-UP
'Top-down' refers to making nano scale structures
by machining and etching techniques.
Microscopic irregularities will always be present.
Bonds cannot be manipulated. Thus new materials
cannot be formed.
Eg. Silicon crystal slicedrequired atomic
scale silicon wafer obtained.
'Bottom-up', or molecular nanotechnology,
applies to building organic and inorganic
structures atom-by-atom, or molecule-bymolecule.
Atomic scale manufacturing is devoid of all
possible irregularities.
Manipulation of bonds enables creation of new
materials with desired properties.
Eg. Silicon atoms assembled by suitable
techniques required atomic scale silicon wafer
obtained.
Thus molecular nanotechnology should let us :
Get essentially every atom in the right place.
Make almost any structure consistent with the laws of physics that we can specify in
molecular detail.
Have manufacturing costs not greatly exceeding the cost of the required raw materials
and energy.
There are basically two ways to fabricate nanodevices:
Self assembly
Positional control
Self Assembly
The ability of chemists to synthesize what they want by stirring things together is truly
remarkable. Imagine building a radio by putting all the parts in a bag, shaking, and pulling
out the radio -- fully assembled and ready to work! Self assembly -- the art and science of
arranging conditions so that the parts themselves spontaneously assemble into the desired
structure -- is a well established and powerful method of synthesizing complex molecular
structures.
A basic principle in self assembly is selective stickiness: if two molecular parts have
complementary shapes and charge patterns -- one part has a hollow where the other part has a
bump, and one part has a positive charge where the other part has a negative charge -- then
they will tend to stick together in one particular way. By shaking these parts around --
something which thermal noise does for us quite naturally if the parts are floating in solution
-- the parts will eventually, purely by chance, be brought together in just the right way and
combine into a bigger part. This bigger part can combine in the same way with other parts,
letting us gradually build a complex whole from molecular pieces by stirring them together
and shaking.
Many viruses use this approach to make more viruses -- if you stir the parts of the T4
bacteriophage together in a test tube, they will self assemble into fully functional viruses.
Positional devices and positionally controlled reactions
While self assembly is a path to nanotechnology, by itself it would be hard pressed to make
the very wide range of products promised by nanotechnology. During self assembly the parts
bounce around and bump into each other in all kinds of ways, and if they stick together when
we don't want them to stick together, we'll get unwanted globs of random parts.
Many types of parts have this problem, so self assembly won't work for them. These parts
can't be allowed to randomly bump into each other (or much of anything else, for that matter)
because they'd stick together when we didn't want them to stick together and form messy
blobs instead of precise molecular machines.
We can avoid this problem if we can hold and position the parts. Even though the molecular
parts that are used to make diamond are both indiscriminately and very sticky (more
technically, the barriers to bond formation are low and the resulting covalent bonds are quite
strong), if we can position them we can prevent them from bumping into each other in the
wrong way.
When two sticky parts do come into contact with each other, they'll do so in the right
orientation because we're holding them in the right orientation. In short, positional control at
the molecular scale should let us make things which would be difficult or impossible to make
without it.
If we are to position molecular parts we must develop the molecular equivalent of "arms" and
"hands." We'll need to learn what it means to "pick up" such parts and "snap them together.
One of the first questions we'll need to answer is: what does a molecular-scale positional
device look like Current proposals are similar to macroscopic robotic devices but on a much
smaller scale. The illustrations show a design for a molecular-scale robotic arm proposed by
Eric Drexler, a pioneering researcher in the field. Only 100 nanometers high and 30
nanometers in diameter, this rather squat design has a few million atoms and roughly a
hundred moving parts. It uses no lubricants, for at this scale a lubricant molecule is more like
a piece of grit.
Stiffness
Our molecular arms will be buffeted by something we don't worry about at the macroscopic
scale: thermal noise. This makes molecular-scale objects wiggle and jiggle, just as Brownian
motion makes small dust particles bounce around at random.
The critical property we need here is stiffness. Stiffness is a measure of how far something
moves when you push on it.
Unfortunately, as we make our positional devices smaller and smaller, they will be more and
more subject to thermal noise. To make something that's both small and stiff is more
challenging. It helps to get the stiffest material you can find. Diamond, as usual, is stiffer
than almost anything else and is an excellent material from which to make a very small, very
stiff positional device. Theoretical analysis gives firm support to the idea that positional
devices in the 100 nanometer size range able to position their tips to within a small fraction
of an atomic diameter in the face of thermal noise at room temperature should be feasible.
STEWART PLATFORM
While Drexler's proposal for a small robotic arm is easy to understand and should be
adequate to the task, more recent work has focused on the Stewart platform. This positional
device has the great advantage that it is stiffer than a robotic arm of similar size.
If we want a full six degrees of freedom (X, Y, Z, roll, pitch and yaw) then we must be able
to independently adjust the lengths of six different edges of the polyhedron. If we further
want one triangular face of the polyhedron to remain of fixed size and hold a "tool," and a
second face of the polyhedron to act as the "base" whose size and position is fixed, then we
find that the simplest polyhedron that will suit our purpose is the octahedron.
The advantage of the Stewart platform can now be seen: because the six adjustable-length
edges are either in pure compression or pure tension and are never subjected to any bending
force, this positional device is stiffer than a long robotic arm which can bend and flex. The
Stewart platform is also conceptually simpler than a robotic arm, having fewer different types
of parts; for this reason, we can reasonably expect that making one will be simpler than
making a robotic.
Self replication: making things inexpensively
Positional control combined with appropriate molecular tools should let us build a truly
staggering range of molecular structures -- but a few molecular devices built at great expense
would hardly seem to qualify as a revolution in manufacturing. How can we keep the costs
down
The requirement for low cost creates an interest in self replicating manufacturing systems.
These systems are able both to make copies of themselves and to manufacture useful
products. If we can design and build one such system the manufacturing costs for more such
systems and the products they make (assuming they can make copies of themselves in some
reasonably inexpensive environment) will be very low.
Once the product has been assembled by assemblers and time of production quickened using
replicators, the assemblers are no more needed in them. The miniature devices used to
dissemble these assemblers are known as DISSEMBLERS. They function opposite to the
assemblers by breaking bonds between the atoms of assemblers and reducing them to junk
atoms.
VISUAL IMAGES IN NANOTECHNOLOGY
Nanogears no more than a nanometer wide could be used to construct a matter compiler, which
could be fed raw material to arrange atoms and build a macro-scale structure.
Nanogears no more than a nanometer wide could be used to construct a matter compiler,
which could be fed raw material to arrange atoms and build a macro-scale structure.
A NANO-PUMP A DIFFERENTIAL A FINE MOTION
GEAR CONTROLLER
APPLICATIONS
Dip_Pen Nanolithography
"One molecule thick letters written using
Dip-Pen Nanolithography:
Octadecanethiol is the ink and gold is the
substrate. Visualized with an atomic force
microscope.
A BEARING A HYDROCARBON JOINT
A NANO PUMP A DIFFERENTIAL GEAR A FINE MOTION
CONTROLLER
NANOTECHNOLOGY AS AN ANALOGY
Nanotechnology is likely to change the way almost everything, including medicine,
computers and cars, are designed and constructed. Nanotechnology is anywhere from five to
15 years in the future, and we won't see dramatic changes in our world right away. But let's
take a look at the potential effects of nanotechnology:
The first products made from nanomachines will be stronger fibers. Eventually,
Technology Function Molecular Examples
struts, beams, casins transmit force, hold positions cell walls, microtubules
cables transmit tension collagen, silk
fasteners, glue connect parts intermolecular forces
solenoids, actuators move things muscle actin, myosin
motors turn shafts flagellar motor
drive shafts transmit torque bacterial flagella
bearings support moving parts single bonds
clamps hold workpieces enzymatic binding sites
tools modify workpieces enzymes, reactive molecules
production lines control devices enzyme systems, ribosomes
numerical control systems store and read programs genetic system
we will be able to replicate anything, including diamonds, water and food. Famine
could be eradicated by machines that fabricate foods to feed the hungry.
In the computer industry, the ability to shrink the size of transistors on silicon
microprocessors will soon reach its limits. Nanotechnology will be needed to
create a new generation of computer components. Molecular computers could
contain storage devices capable of storing trillions of bytes of information in a
structure the size of a sugar cube.
Nanotechnology may have its biggest impact on the medical industry. Patients
will drink fluids containing nanorobots programmed to attack and reconstruct the
molecular structure of cancer cells and viruses to make them harmless. There's
even speculation that nanorobots could slow or reverse the aging process, and life
expectancy could increase significantly. Nanorobots could also be programmed to
perform delicate surgeries -- such nanosurgeons could work at a level a thousand
times more precise than the sharpest scalpel. By working on such a small scale, a
nanorobot could operate without leaving the scars that conventional surgery does.
Additionally, nanorobots could change your physical appearance. They could be
programmed to perform cosmetic surgery, rearranging your atoms to change your
ears, nose, eye color or any other physical feature you wish to alter.
Nanotechnology has the potential to have a positive effect on the environment.
For instance, airborne nanorobots could be programmed to rebuild the thinning
ozone layer. Contaminants could be automatically removed from water sources,
and oil spills could be cleaned up instantly. Manufacturing materials using the
bottom-up method of nanotechnology also creates less pollution than
conventional manufacturing processes. Our dependence on non-renewable
resources would diminish with nanotechnology. Many resources could be
constructed by nanomachines. Cutting down trees, mining coal or drilling for oil
may no longer be necessary. Resources could simply be constructed by
nanomachines.
One challenge to effective drug treatment is getting the medication to exactly the
right place. To that end, researchers have been investigating myriad new methods
to deliver pharmaceuticals. New findings indicate that tiny nanocontainers
composed of polymers may one day distribute drugs to specific spots within
individual cells
New findings suggest that artificial leaves comprised of nanocrystals may one day
remove carbon dioxide from the atmosphere--even in the dark
Research suggests that the diminutive tubes can hold twice as much energy as
graphite, the form of carbon currently used as an electrode in many rechargeable
lithium batteries
CHALLENGES
Things behave substantially differently in the micro domain. Forces related to
volume, like weight and inertia, tend to decrease in significance. Forces related to
surface area, such as friction and electrostatics, tend to become large. And forces
like surface tension that depend upon an edge become enormous. It takes awhile
to get one's micro intuition sorted out. Some people have come up with obstacles
which raise doubts about the question:
Will it work
Will Thermal Vibrations Mess Things Up"
Will Quantum Uncertainty Mess Things Up"
"Will Loose Molecules Mess Things Up"
Will Chemical Instability Mess Things Up
ETHICAL ISSUES
Some people have recently, publicly (and belatedly) realized that nanotechnology might create new
concerns that we should address.
Deliberate abuse, the misuse of a technology by some small group or nation to cause great harm, is
best prevented by measures based on a clear understanding of that technology. Nanotechnology
could, in the future, be used to rapidly identify and block attacks. Distributed surveillance systems
could quickly identify arms buildups and offensive weapons deployments, while lighter, stronger, and
smarter materials controlled by powerful molecular computers would let us make radically improved
versions of existing weapons able to respond to such threats.
Replicating manufacturing systems could rapidly churn out the needed defenses in huge quantities.
Such systems are best developed by continuing a vigorous R&D program, which provides a clear
understanding of the potential threats and countermeasures available.
Besides deliberate attacks, the other concern is that a self-replicating molecular machine could
replicate unchecked, converting most of the biosphere into copies of itself. Some precautionary
measures include such common sense principles as: artificial replicators must not be capable of
replication in a natural, uncontrolled environment; they must have an absolute dependence on an
artificial fuel source or artificial components not found in nature; they must use appropriate error
detection codes and encryption to prevent unintended alterations in their blueprints; and the like.
CONCLUSION
The promises of nanotechnology sound great, don't they Maybe even unbelievable But
researchers say that we will achieve these capabilities within the next century. And if
nanotechnology is, in fact, realized, it might be the human race's greatest scientific
achievement yet, completely changing every aspect of the way we live.
Nanotechnology's potential to improve the human condition is staggering: we would be
shirking our duty to future generations if we did not responsibly develop it.
BIBLIOGRAPHY
Electronics for you
yahoosearch.com
rediffsearch.com
howstuffworks.com
Unbounding the future