ABSTRACT
Lately there are frequent news about the new findings
in Nanotechnology. There seems to be a race going on between various
international labs and intense research is being carried out in the area of this
new science. Enormous emphasis is being placed on Nanotechnology and many
researchers are looking towards Nanotechnology, to find answers, in many areas
specially medicine and electronics. Nano-science and Nanotechnology seem to be
the best of the solution provider today.21st century belongs to Gene
technology and Nanotechnology.
It would not be out of place to mention that
Nanotechnology has been introduced as a subject in some of the developed
countries, as they see the future of S & T will be in Nano-based approach.
In India, the importance of Nanotechnology came to
lime light quite recently. While many researches have been carrying out on the
Nano Technology clearly shows that the next wave of technology after the
computers and management - is the Nanotechnology. There may be few institutions
in India doing serious research in the Nano field, but one does not hear of the
exact nature of research work being done. Awareness in student community about
this emerging technology would help in attracting more talent.
It is high time to wake up and start serious work on
Nanotechnology and educational activity to keep up with the advance countries.
It is also presumed that Nanotechnology would touch every other sphere of
technical activities and make the current technologies look like bullock cart of
18th Century.
Nano science and technologies are likely to touch every
aspect of our life in the next few years. Many Big names are investing Billions
of Dollars to explore and research out in this direction. Like computer
technology this technology also does not require a lot of investment but
knowledge Engineering (Brain power) and hard work. This aspect of nanotechnology
gives a definite leverage to India - a country with large Brain power.
INTRODUCTION
Man himself is a nature machine equipped with complex
tools like limbs and the five senses. Man with these limited, but versatile
tools has build many structures like building, cities, Dams and developed
thousands of other resources for his own benefit and is controlling these
resources as his personal property. One can go on beyond the current day science
to keep civil Engineering based building technologies, with a
conventional approach, but a deeper look at the nature which build the self
reproducing and learning machines from much smaller structures that is to say
with fewer groups of "Atoms and Molecules".
Man has been trying to study the nature’s smaller
scale technology and has been progressively investigating smaller and smaller
level of nature’s creation. The human cells, Smaller animals, microbes,
bacteria, Virus, Fungi etc. As the science has been historically understood, It
has been divided into very nearly neat division of Physics, Chemistry, Biology
Etc. Nature while engaged in its creativity/construction activity never
distinguishes different streams or rules of Science and technology.
What are we driving at? The Nanotechnology tries to
mimic the nature and takes the man more nearer to the Creator by further few
more steps.
Nano science and technologies are likely to touch
every aspect of our life in the next few years. Many Big names are investing
Billions of Dollars to explore and research out in this direction. Like computer
technology this technology also does not require a lot of investment but
knowledge Engineering (Brain power) and hard work. This aspect of nanotechnology
gives a definite leverage to India - a country with large Brain power.
Applications of Nanotechnology ranges from - reducing
the size of electronic gadgets (Bell Labs has already come out with a self
assembled Transistors of single molecule size ) to designing virus to kill
bacteria.
Nanotechnology is a hybrid science combining
engineering and chemistry. Atoms and molecules stick together because they have
complementary shapes that lock together, or charges that attract. Just like with
magnets, a positively charged atom will stick to a negatively charged atom. As
millions of these atoms are pieced together by nanomachines, a specific product
will begin to take shape. The goal of nanotechnology is to manipulate atoms
individually and place them in a pattern to produce a desired structure.
DEFINITION
There is no accepted definition of Nanotechnology or
Nano science. Nanotechnology refers to components build of the size 20 to 30
Nano Meters. They are also supposed to be self replicating or self assembling
and this aspect get confused with cloning. Self-assembling implies, you put the
ingredients in one place and they assemble into some thing useful where as
replicating implies, You have a assembled component and it replicates it self in
to thousands of more like itself. Cloning refers to meddling with nature at
reproductive level of animals including human. Self replicating or self
assembling does not refer to living being but manipulation done on organic and
inorganic materials at molecular level. This separation between living and
nonliving gets blurred at nano level. Any way whether self assembling or self
replicating once the process is on, little effort is required externally to
manufacture them. The cost benefit can be immediately sensed.
"Nano Technology" in the broader and more
inclusive definition is referred as “molecular nanotechnology" or
"molecular manufacturing." The term Nanotechnology was
created by Tokyo Science University professor Norio Taniguchi in 1974 to
describe the precision manufacture of materials with nanometre tolerances. In
the 1980s the term
was reinvented and its definition expanded by K Eric Drexler, particularly in
his 1986 book Engines
of Creation: The Coming Era of Nanotechnology.
He explored this subject in much greater technical depth in his
MIT doctoral
dissertation, later expanded into Nanosystems.
Nanotechnology, while not providing a cure for
everything, is defined by the length scale when scientists and engineers
discover new phenomena. It provides exquisite new tools to engineer novel
materials and devices at the nanoscale, and to study biology.
SCALE
Although a metre is defined by
the International Standards Organization as `the length of the path travelled by
light in vacuum during a time interval of 1/299 792 458 of a second' and a
nanometre is by definition 10- 9 of a metre. A nanometer, one billionth of a meter, is about
10,000 times narrower than a human hair.
NATURE_-MASTER OF NANO TECHNOLOGY
Nature is a master at operating at the nano scale.Ithas always dependend on nano
scale operations for the functioning of life, for example: the metabolic
activites within the cells that sustain life ; the fertilization of embryo in
reproduction ; and the interaction of cellular components for cell movement,to
name a few.
The ecosystem is another natural system that is heavily dependent on nanotechnology – nanoparticles are important in the formation of both rain and snow. Small airborne particles known as condensation nuclei act as the nucleation site, or seed site, on which water condenses to form raindrops or snowflakes depending on the temperature. The particles can vary in size from thousands of nanometres down to a few hundreds of nanometres, or less. These nanoparticles can arise from a variety of sources including dust, volcanoes, and forest or factory smoke, phytoplankton or ocean salt.
Four such examples of nature’s nanotechnologies are highlighted below.
|
|
Size range approx. |
|
Sea salt aerosols are generated by the sea spray produced by
waves at high wind speeds and by the bursting of entrained air bubbles
in the white cap formation. These particles are emitted into the
atmosphere where they act, along with other particles, as seed sites for
raindrops and snowflakes. |
large variability 10,000nm – nm |
|
Plankton come in many sizes and forms and can be subdivided
according to their size. Pico- and femto-plankton range in size from a
few nanometres to hundreds of nanometres and consist of some
phytoplankton, marine bacteria and viruses. |
2–1500 nm |
|
Actin and myosin molecules form the system responsible for
muscle contraction. The system operates by a series of steps where the
head of myosin molecule pulls the actin past itself by 10–28nm each
step. |
Steps of contraction: 10nm–28nm |
|
Glucose and glucose oxidase – all cells require glucose as a
fuel for their metabolic activity. Energy is released from glucose when
it is precisely positioned relative to the glucose oxidase enzyme –
the lock and key mechanism. |
Glucose: 0.6nm glucose oxidase: 5nm |
Nanotechnology has a long and rich history.Pottery using nano-sized particles has been in use for thousands of years. The oldest known such object is thought to be the Lycurgus chalice, which dates back to the late fourth century ad, and which can be seen in the British Museum. The Roman chalice has a raised frieze showing the myth of King Lycurgus, and is made from glass which appears green in reflected light, but when light is shone directly through the glass it appears translucent red.
This unusual optical effect is caused by 70nm particles of silver and gold contained within the glass. (The glass contains 40 parts per million of gold and 300 parts per million of silver, and the particles consisting of seven parts silver to three parts gold.) It is possible that, while the glass was being made, some scrap metal and slag containing silver and gold was added, and the unusual effect was achieved by accident. The understanding that glass could be coloured red by adding small amounts of gold is often credited to Johann Kunckel, who worked in Germany in the late seventeenth century.
The chalice, however, is not a unique example of nanoparticles being used in centuries past; pottery from the ninth century ad from the Mesopotamian era also contains nanoparticles in glazed films applied to ceramic pottery. The technique was brought to Spain in medieval times, as Arabian culture spread, and it then migrated to Italy, where Renaissance pottery made much use of the effect in polychrome lustres on pottery.
RISE OF NANO TECHNOLOGY:
The
first mention of modern nanotechnology occurred in a talk given by Richard
Feynman in 1959, entitled There's
Plenty of Room at the Bottom.
Feynman suggested a means to develop the ability to manipulate atoms and
molecules "directly", by developing a set of one-tenth-scale machine
tools analogous to those found in any machine shop. These small tools would then
help to develop and operate a next generation of one-hundredth-scale machine
tools, and so forth. As the sizes get smaller, we would have to redesign some
tools because the relative strength of various forces would change. Gravity would
become less important, surface tension would become more important, Van
der Waals attraction would become important, etc. Feynman
mentioned these scaling issues during his talk. Nobody has yet effectively
refuted the feasibility of his proposal.
For constructing any machine we require suitable
tools to add and place the
component in the precise location. The complexity of the tool increases as the
size of the component decreases. Imagine a building a component consisting of
few molecules - What tools can be used, how they would look like? And How to use
them? Development of the right tools for Nanotechnology itself should be a
interesting issue
Two approaches can be taken when making something at the nanoscale: these are known as the ‘top-down’ approach and the ‘bottom-up’ approach.
TOP DOWN APPROACH:
The top-down approach is analogous to making a stone statue. You take a bulk piece of material and modify it, by carving or cutting in the case of stone, until you have made the shape you want. The process involves material wastage and is limited by the resolution of the tools you can use, restricting the smallest sizes of the structures made by these techniques.
Examples of this kind of approach include the various types of lithographic techniques (such as photo-, ion beam-, electron- or X-ray- lithography) cutting, etching and grinding.
Lithography is a selective process that allows the patterning of a desired design onto the starting material. A mask is used to protect the areas of material that need to be maintained, while the rest of the material is exposed to a beam of UV, ions, electrons or X-rays. Etching and/or deposition on the surface is then performed, leaving the desired shape.
These techniques have been used to great effect to produce the miniaturisation of electronic components, such as computer chips, MEMS (micro-electromechanical systems) in consumer products such as computer hard drives, and CD and DVD players.
Lithography has fuelled the continued miniaturisation of these components so that Moore’s law has continued to be applicable, namely that the number of transistors per integrated circuit doubles every couple of years.
Quantum well lasers and high-quality optical mirrors are also fabricated using top-down techniques.
BOTTOM UP APPROACH:
The second approach to producing nanotechnology is known as the bottom-up approach, and can be thought of as the same approach one would take to building a house: one takes lots of building blocks and puts them together to produce the final bigger structure. There is less wastage with this technique, and strong covalent bonds will hold the constituent parts together. However, this technique is limited in how big the structures can be made.
A good example of this kind of approach is found in nature; all cells use enzymes to produce DNA by taking the component molecules and binding them together to make the final structure. Chemical synthesis, self-assembly, and molecular fabrication are all examples of bottom-up techniques.
Self-assembly occurs when little manipulation occurs, but components spontaneously come together to form ordered nanoscale structures, for instance in the formation of nanotubes and some monolayers.
Molecular fabrication is the only one of these techniques where molecules or atoms are manipulated into position one by one. Consequently this is a laborious process which has yet to address the problems of scaling up the technique for manufacture. It has been speculated that this process could be scaled up using self-replicating machines that would allow parallel production, leading to further speculation about the replication process running out of control. Recently, however, Eric Drexler, the scientist who first proposed these scenarios, has retracted his suggestion of out-of-control replication leading to ‘gray goo’.
Cosmetics, fuel additives, and experimental atomic and molecular devices are all examples of structures made using bottom-up techniques.
The limits of feature size and quality of these two approaches have started to converge in recent years, leading to new hybrid techniques of manufacture.
STRUCTURES USED TO BUILD NANO THINGS:
Structures used Common in Nanotechnology are,
Nanotube are the most common structures used in Nano
technology. Nanotubes are made of carbon atoms bonded into honeycomb-like shapes
with enormous strength and electrical conductivity.
Recently another structure made of different oxides
is Nano belt. Nano belt manufacturing seems to be simpler and produces belts
which are longer than Nanotubes.
Nanopores is another structure the pores are so small that DNA
separation is being attempted using this structure.
Quantum dots are minuscule molecule making up tiny crystals that
glow when stimulated by ultraviolet light.
Nanoshells
are miniscule
beads coated with gold.
Dendrimers are man-made molecules about the size of an average
protein, and have a branching shape
APPLICATIONS OF NANO TECHNOLOGY
MONITORING
PATIENTS:
Most animal cells are 10,000 to 20,000 nanometers in
diameter. This means that nanoscale devices (less than 100 nanometers) can enter
cells and interact with DNA and proteins. Tools developed through nanotechnology
may be able to detect disease in a very small samples of cells or tissue. They
could be made to enter and monitor cells within a living body.
In order to successfully detect cancer at its
earliest stages, scientists must be able to detect molecular changes even when
they occur only in a small percentage of cells. This means the necessary tools
must be extremely sensitive. The potential for nanostructures to enter and
analyze single cells suggests they could meet this need.
Components or tools built with nanotechnology could
travel in the body and transmit or take corrective action to repair an organ of
body very effectively without disturbing the healthy cells. The application in
the medical field is limited only by imagination.
NANOTECHNOLOGY IN CANCER TREATMENT:
Another interesting nanodevice is the nanopore.
Improved methods of reading the genetic code will help researchers detect errors
in genes that may contribute to cancer. Scientists believe Nanopores, tiny holes
that allow DNA to pass through one strand at a time, will make DNA sequencing
more efficient. As DNA passes through a nanopore, scientists can monitor the
shape and electrical properties of each base, or letter, on the strand. Because
these properties are unique for each of the four bases that make up the genetic
code, scientists can use the passage of DNA through a nanopore to decipher the
encoded information, including errors in the code known to be associated with
cancer.
Nanotubes is another nanodevice that will help identify DNA changes
associated with cancer is the nanotube. Nanotubes are carbon rods about half the
diameter of a molecule of DNA that not only can detect the presence of altered
genes, but may help researchers pinpoint the exact location of those changes.
To prepare DNA for nanotube analysis, scientists must
attach a bulky molecule to regions of the DNA that are associated with cancer.
They can design tags that seek out specific mutations in the DNA and bind to
them.
Another minuscule molecule that will be used to detect cancer is a
quantum dot. Quantum dots are tiny crystals that glow when they are stimulated
by ultraviolet light. The wavelength, or color, of the light depends on the size
of the crystal. Latex beads filled with these crystals can be designed to bind
to specific DNA sequences. By combining different sized quantum dots within a
single bead, scientists can create probes that release distinct colors and
intensities of light. When the crystals are stimulated by UV light, each bead
emits light that serves as a sort of spectral bar code, identifying a particular
region of DNA.
Nanoshells are miniscule beads coated with
gold. By manipulating the thickness of the layers making up the nanoshells,
scientists can design these beads to absorb specific wavelengths of light. The
most useful nanoshells are those that absorb near-infrared light, which can
easily penetrate several centimeters of human tissue. The absorption of light by
the nanoshells creates an intense heat that is lethal to cells.
Research is being done on a number of Nano particles created to
facilitate drug delivery. One such molecule with potential to link treatment
with detection and diagnosis is known as a dendrimer. Dendrimers are man-made
molecules about the size of an average protein, and have a branching shape. This
shape gives them vast amounts of surface area to which scientists can attach
therapeutic agents or other biologically active molecules. Researchers aim
eventually to create nanodevices that do much more than deliver treatment.A
single dendrimer can carry a molecule that recognizes cancer cells, a
therapeutic agent to kill those cells, and a molecule that recognizes the
signals of cell death. Researchers hope to manipulate dendrimers to release
their contents only in the presence of certain trigger molecules associated with
cancer. Following drug release, the dendrimers may also report back whether they
are successfully killing their targets.
NANO
TECHNOLOGY IN THE FIELD OF ELECTRONICS AND IN OTHER UTILITIES :
Colour displays - Organic Light Emitting
Diodes (OLED) are nanostructured polymer films, less than 500nm thick
which can be used as lighter, thinner, more flexible, and less power-consuming
colour displays. Companies like Cambridge Display Technologies, Universal
Display Corporation and Kodak are developing the films for use in a whole range
of flat panel displays (e.g. cameras)
Organic Light Emitting Diode
Sunscreen – 65nm
particles of Solar panels – solar cells using conducting
polymers and nano-based particles are being produced by Nanosolar Inc. in
California. The polymer and nanoparticles are mixed and then printed on to a
polymer surface forming a layer 200nm thick. It produces cheap, flexible and
easier to make solar cells.
titanium oxide are being used in new sunscreens. These particles, made by
companies like Oxonica, absorb UV light for longer with significantly less free
radical formation (which leads to cell damage and skin ageing) than existing
sunscreens.
Tennis racquet – Babolat are
producing a racquet that incorporates carbon nanotubes into the frame. The
racket is said to be five times stiffer than standard carbon racquet and bends
less when the ball impacts. The reduction in the energy lost means that the
player’s return is stronger.
Some of the newer products that are appearing that incorporate nanotechnology
include: synthetic bone; biosensors, devices that can analyse
blood composition to detect disease and illness; longer-life tennis balls;
fabrics that have been treated with nanoparticles to produce stain-repellent
clothing available in the high street; glass that cleans itself;
stronger, lighter and scratch-resistant nanocomposite step assists on
vans; rocket propellant that burns at double the normal rate; super-tough
automobile and plane coatings; and fuel additives that
improve fuel consumption and lead to reduced emissions of noxious exhaust gases.
Nanofilms – layers of material a few molecules thick that are stable, able to cover large areas, and can provide scratch-resistant, low-friction or optical high-performance coatings. Applications include windows with self-cleaning properties.
Nano-optics – optical structures or devices in which the focusing or scattering of light is controlled by features that have sizes significantly less than the wavelength of light (that is, less than 400–700nm). Applications are already being made in areas of displays, cameras and telecommunications.
Quantum dots – semiconductor particles that have dimensions of a few nm such that their electronic and optical properties depend mainly on their size. They have already found application in size-tunable ‘labels’ for biological molecules and are expected to form the basis of new light sources and electronic computers.
Nanomaterials – materials that consist of or contain nanoparticles, and can offer improved properties, such as lower weight, or higher strength. Applications currently ing nanomaterials include tennis racquets and solar cells.
Nanoelectronics is a nanotechnology relating to the miniaturisation of
electronic devices. The drive to increase device density and operating speed has
meant that electronic devices have entered the nanoscale, and new fabrication
techniques, components and changed properties have to be considered.
Nano Transistor
Scientists
from Lucent Technologies' Bell Labs have created organic transistors with a
single-molecule channel length, setting the stage for a new class of high-speed,
inexpensive carbon-based electronics. In these new molecular-scale transistors,
fabricated by a multidisciplinary team of Bell Labs researchers, the length of
one molecule defines the channel's physical dimension; it is more than a factor
of ten smaller than anything that has been demonstrated even with the most
advanced lithography techniques. Scientists have been looking for alternatives
to conventional silicon electronics for many years, because they anticipate that
the continuing miniaturization of silicon-based integrated circuits will subside
in approximately a decade as fundamental physical limits are reached. Some of
this research has been aimed at producing molecular-scale transistors, in which
single molecules are responsible for the transistor action - switching and
amplifying electrical signals. Bell Labs scientists Hendrik Schon, Zhenan Bao
and Hong Meng have now succeeded in fabricating molecular-scale transistors that
rival conventional silicon transistors in performance, using a class of organic
(carbon-based) semiconductor material known as thiols. "When we tested
them, they behaved extremely well as both amplifiers and switches," said
Schon, an experimental physicist who was the lead researcher.
The novel nano-technology is required for realizing the nano-scale
devices such as single electron transistor (SET) and metal/insulator tunnel
transistor (MITT). Recently, new methods to fabricate a nanometer region of
metals by using such as a tip of a scanning tunneling microscope (STM) have been
reported. However, these do not appear as industrially acceptable techniques.
Then, a new nano-technology utilizing conventional photolithography was
proposed. A contact pattern-mask with nanometer-size slits was fabricated by
combination of conventional photo-lithography and anodic oxidation of side-wall
of metal. In this study the application of the pattern-mask is shown.
Nanometer-size fabrication of semiconductor substrates and metal thin lines by
using the pattern-mask is attempted
Nanomagnetics is a
nanotechnology relating to the miniaturisation of magnetic materials. This area
is developing in conjunction with the drive for more powerful and higher
capacity computer-driven devices.
Stain-repellent trousers reach the high street
Clothing embedded with nanoparticles that produce a stain-repellent coating has
been developed. Nano-care™ khakis have the fabric fibres coated with
nanowhiskers 10–100nm in length. This new stain-repellent fabric is available
from a number of high
street retailers and is available in trousers, shirts and ties.
Prototype
nano-solar cells :
Automobile
The changes in electronics and other field due to
nanotechnology would possibly make the automobile run on fuel assembled from
Nanotechnology. The engine may be running in some other way not comprehendible
today.
Bearings and Springs Made from
Carbon Nanotubes
Berkeley - Physicists at the University of California, Berkeley, have peeled the tips off carbon nanotubes to make seemingly frictionless bearings so small that some 10,000 would stretch across the diameter of a human hair.
The minuscule bearings are actually telescoping nanotubes with the inner tube spinning about its long axis. When sliding in and out, however, they act as nanosprings.
Both the springs and bearings, which appear to move with no wear and tear, could be important components of the microscopic and world.
Micromachines, called MEMS devices, for microelectromechanical systems, are on the scale of a human hair. Nanoelectromechanical systems (NEMS) are a thousand times smaller, on the scale of a nanometer or a billionth of a meter. Nanotubes, for example, are hollow cages of carbon atoms several nanometers thick and up to several thousand nanometers long, looking on the molecular level like chicken wire stretched around a baguette.
"Friction is a big problem with MEMS, but these nanoscale bearings just slide as if there's no friction," said John Cumings, a graduate student in the Department of Physics at UC Berkeley who created the bearings. "As a lower limit, friction is a thousand times smaller than you find in conventional MEMS devices made with silicon or silicon nitride."
Evanston, IL — Northwestern University researchers have become the first to image and analyze a class of nanostructures that are stronger and lighter than steel and that could be used in the transportation industry, possibly as hard coatings on gears to improve the efficiency of vehicles or as an oxidation-resistant outer coating for airplane windows.Once developed fully, the nanostructures also could be embedded in other materials, such as polymers, to increase their strength.
Nanotechnology, like any other branch of science, is primarily concerned with understanding how nature works. We have discussed how the efforts are put to produce devices and manipulate matter are still at a very primitive stage compared to nature. Nature has the ability to design highly energy efficient systems that operate precisely and without waste, fix only that which needs fixing, do only that which needs doing, and no more. While many branches of what now falls under the umbrella term nanotechnology are not new, it is the combination of existing technologies with our new found ability to observe and manipulate at the atomic scale that makes nanotechnology so compelling from scientific, business and political viewpoints.
For the scientist, advancing the sum total of human knowledge has long been the driving force behind discovery, from the gentleman scientists of the 17th and 18th centuries to our current academic infrastructure. Nanotechnology is at a very early stage in our attempts to understand the world around us, and will provide inspiration and drive for many generations of scientists.
For business, nanotechnology is no different from any other technology: it will be judged on its ability to make money. This may be in the lowering of production costs by, for example, the use of more efficient or more selective catalysts in the chemicals industry, by developing new products such as novel drug delivery mechanisms or stain resistant clothing, or the creation of entirely new markets, as the understanding of polymers did for the multi-billion euro plastics industry.
Politically, it can be argued that fear is the primary motivation. Nanotechnology promises far more significant economic, military and cultural changes than those created by the internet, and with technology advancing so fast, and development and adoption cycles becoming shorter, playing catch-up will not be an option for governments who are not already taking action.
Maybe the greatest short term benefit of nanotechnology is in bringing together the disparate sciences, physical and biological, who due to the nature of education often have had no contact since high school. Rather than nanosubmarines or killer nanobots, the greatest legacy of nanotechnology may well prove to be the unification of scientific disciplines and the resultant ability of scientists, when faced with a problem, to call on the resources of the whole of science, not just of one discipline.