NANOTECHNOLOGY

Fullerene Nanogears - GPN - 2000-oo1535.jpg

 Nanotechnology, also shortened to nanotech, is the use of count on an atomic, molecular, and supramolecular scale for industrial functions. The earliest, sizeable description of nanotechnology stated the specific technological purpose of exactly manipulating atoms and molecules for fabrication of macroscale merchandise, also now called molecular nanotechnology. A greater generalized description of nanotechnology become in the end established by means of the National Nanotechnology Initiative, which defined nanotechnology because the manipulation of rely with at the least one measurement sized from 1 to one hundred nanometers. This definition displays the reality that quantum mechanical effects are essential at this quantum-realm scale, and so the definition shifted from a specific technological purpose to a studies class which includes all sorts of research and technologies that cope with the unique homes of matter which occur beneath the given size threshold. It is consequently not unusual to look the plural form "nanotechnologies" as well as "nanoscale technologies" to refer to the wide variety of research and programs whose common trait is size.

Nanotechnology as defined with the aid of size is evidently huge, which include fields of science as diverse as surface science, natural chemistry, molecular biology, semiconductor physics, strength storage, engineering, microfabrication, and molecular engineering. The associated studies and packages are equally diverse, ranging from extensions of conventional device physics to completely new procedures based totally upon molecular self-assembly, from developing new substances with dimensions at the nanoscale to direct control of matter on the atomic scale.

Scientists currently debate the future implications of nanotechnology. Nanotechnology may be able to create many new materials and devices with a extensive range of packages, including in nanomedicine, nanoelectronics, biomaterials energy manufacturing, and client merchandise. On the other hand, nanotechnology raises the various equal troubles as any new technology, consisting of concerns approximately the toxicity and environmental impact of nanomaterials, and their capability outcomes on international economics, in addition to hypothesis approximately numerous doomsday scenarios. These worries have brought about a debate amongst advocacy agencies and governments on whether unique regulation of nanotechnology is warranted.

Origins

The concepts that seeded nanotechnology have been first discussed in 1959 by using famend physicist Richard Feynman in his talk There's Plenty of Room at the Bottom, in which he defined the possibility of synthesis via direct manipulation of atoms.

Comparison of Nanomaterials Sizes

 The time period "nano-era" become first used by Norio Taniguchi in 1974, although it became not widely known. Inspired by way of Feynman's concepts, K. Eric Drexler used the time period "nanotechnology" in his 1986 ebook Engines of Creation: The Coming Era of Nanotechnology, which proposed the concept of a nanoscale "assembler" which might be able to construct a duplicate of itself and of different objects of arbitrary complexity with atomic manipulate. Also in 1986, Drexler co-based The Foresight Institute (with which he is now not affiliated) to help boom public attention and information of nanotechnology concepts and implications.

The emergence of nanotechnology as a field within the Eighties took place through convergence of Drexler's theoretical and public work, which evolved and popularized a conceptual framework for nanotechnology, and excessive-visibility experimental advances that drew additional wide-scale interest to the prospects of atomic manipulate of count. In the 1980s, two major breakthroughs sparked the increase of nanotechnology in the modern-day era. First, the invention of the scanning tunneling microscope in 1981 which supplied unprecedented visualization of individual atoms and bonds, and became efficiently used to control character atoms in 1989. The microscope's builders Gerd Binnig and Heinrich Rohrer at IBM Zurich Research Laboratory obtained a Nobel Prize in Physics in 1986. Binnig, Quate and Gerber also invented the analogous atomic force microscope that year.

Buckminsterfullerene C60, additionally referred to as the buckyball, is a consultant member of the carbon systems referred to as fullerenes. Members of the fullerene family are a main concern of studies falling underneath the nanotechnology umbrella.

 Second, fullerenes had been observed in 1985 by using Harry Kroto, Richard Smalley, and Robert Curl, who collectively gained the 1996 Nobel Prize in Chemistry. C60 became now not first of all described as nanotechnology; the term changed into used regarding next paintings with associated carbon nanotubes (sometimes called graphene tubes or Bucky tubes) which advised capacity applications for nanoscale electronics and gadgets. The discovery of carbon nanotubes is essentially attributed to Sumio Iijima of NEC in 1991, for which Iijima gained the inaugural 2008 Kavli Prize in Nanoscience.

A nanolayer-base steel–semiconductor junction (M–S junction) transistor become first of all proposed by A. Rose in 1960, and fabricated through L. Geppert, Mohamed Atalla and Dawon Kahng in 1962. Decades later, advances in multi-gate era enabled the scaling of metallic–oxide–semiconductor discipline-impact transistor (MOSFET) gadgets right down to nano-scale tiers smaller than 20 nm gate length, starting with the FinFET (fin discipline-effect transistor), a 3-dimensional, non-planar, double-gate MOSFET. At UC Berkeley, a group of researchers together with Digh Hisamoto, Chenming Hu, Tsu-Jae King Liu, Jeffrey Bokor and others fabricated FinFET gadgets down to a 17 nm process in 1998, then 15 nm in 2001, after which 10 nm in 2002.

In the early 2000s, the sphere garnered increased scientific, political, and commercial interest that led to both controversy and development. Controversies emerged regarding the definitions and capacity implications of nanotechnologies, exemplified with the aid of the Royal Society's record on nanotechnology. Challenges had been raised regarding the feasibility of applications predicted by advocates of molecular nanotechnology, which culminated in a public debate among Drexler and Smalley in 2001 and 2003.

Meanwhile, commercialization of products based totally on improvements in nanoscale technologies started out rising. These merchandise are confined to bulk programs of nanomaterials and do now not involve atomic manage of depend. Some examples include the Silver Nano platform for using silver nanoparticles as an antibacterial agent, nanoparticle-primarily based transparent sunscreens, carbon fiber strengthening the usage of silica nanoparticles, and carbon nanotubes for stain-resistant textiles.

Governments moved to sell and fund research into nanotechnology, which include inside the U.S. With the National Nanotechnology Initiative, which formalized a size-primarily based definition of nanotechnology and set up investment for studies at the nanoscale, and in Europe through the European Framework Programmes for Research and Technological Development.

By the mid-2000s new and serious medical attention began to flourish. Projects emerged to supply nanotechnology roadmaps which middle on atomically particular manipulation of depend and talk current and projected skills, dreams, and programs.

In 2006, a team of Korean researchers from the Korea Advanced Institute of Science and Technology (KAIST) and the National Nano Fab Center advanced a 3 nm MOSFET, the world's smallest nanoelectronic tool. It changed into based totally on gate-all-round (GAA) FinFET technology.
Over sixty countries created nanotechnology studies and development (R&D) government packages among 2001 and 2004. Government funding become handed with the aid of corporate spending on nanotechnology R&D, with most of the funding coming from organizations based in the United States, Japan and Germany. The pinnacle 5 agencies that filed the maximum intellectual patents on nanotechnology R&D between 1970 and 2011 had been Samsung Electronics (2,578 first patents), Nippon Steel (1,490 first patents), IBM (1,360 first patents), Toshiba (1,298 first patents) and Canon (1,162 first patents). The top five businesses that posted the maximum scientific papers on nanotechnology studies among 1970 and 2012 have been the Chinese Academy of Sciences, Russian Academy of Sciences, Centre national de l.  A. Recherche scientifique, University of Tokyo and Osaka University.

 Fundamental concepts

 Nanotechnology is the engineering of practical structures on the molecular scale. This covers both modern-day work and ideas which might be more advanced. In its unique experience, nanotechnology refers back to the projected capability to assemble items from the bottom up, the usage of techniques and gear being advanced nowadays to make complete, high-overall performance merchandise.

One nanometer (nm) is one billionth, or 10−nine, of a meter. By assessment, usual carbon-carbon bond lengths, or the spacing between those atoms in a molecule, are inside the variety 0.12–0.15 nm, and a DNA double-helix has a diameter around 2 nm. On the opposite hand, the smallest cellular existence-paperwork, the micro organism of the genus Mycoplasma, are around 2 hundred nm in duration. By conference, nanotechnology is taken as the size variety 1 to a hundred nm following the definition utilized by the National Nanotechnology Initiative inside the US. The lower limit is ready with the aid of the scale of atoms (hydrogen has the smallest atoms, which are approximately 1 / 4 of a nm kinetic diameter) due to the fact nanotechnology ought to build its gadgets from atoms and molecules. The higher restriction is greater or less arbitrary but is round the size under which the phenomena no longer discovered in large structures begin to become apparent and may be made use of within the nano tool. These new phenomena make nanotechnology wonderful from gadgets which can be merely miniaturised versions of an equal macroscopic device; such devices are on a larger scale and come beneath the outline of microtechnology.

To put that scale in every other context, the comparative size of a nanometer to a meter is the same as that of a marble to the size of the earth. Or every other way of putting it: a nanometer is the quantity a mean guy's beard grows inside the time it takes him to elevate the razor to his face.

Two major procedures are used in nanotechnology. In the "bottom-up" method, substances and devices are constructed from molecular additives which collect themselves chemically with the aid of standards of molecular recognition. In the "pinnacle-down" approach, nano-objects are constructed from large entities without atomic-stage manipulate.

Areas of physics which include nanoelectronics, nanomechanics, nanophotonics and nanoionics have evolved at some point of the previous couple of decades to offer a simple scientific foundation of nanotechnology.

 Large to smaller : a materials perspective

Image of reconstruction on a easy Gold(100) floor, as visualized the use of scanning tunneling microscopy. The positions of the character atoms composing the surface are seen.

 

 

Several phenomena emerge as reported as the size of the gadget decreases. These consist of statistical mechanical outcomes, in addition to quantum mechanical consequences, for example the "quantum size effect" wherein the digital residences of solids are altered with remarkable reductions in particle length. This effect does no longer come into play by going from macro to micro dimensions. However, quantum consequences can end up sizable when the nanometer size range is reached, usually at distances of a hundred nanometers or much less, the so-referred to as quantum realm. Additionally, some of bodily (mechanical, electrical, optical, and so on.) residences change when as compared to macroscopic systems. One example is the increase in surface location to quantity ratio altering mechanical, thermal and catalytic residences of substances. Diffusion and reactions at nanoscale, nanostructures substances and nanodevices with rapid ion delivery are commonly referred to nanoionics. Mechanical properties of nanosystems are of interest inside the nanomechanics studies. The catalytic activity of nanomaterials also opens capacity dangers of their interplay with biomaterials.

Materials decreased to the nanoscale can show exceptional properties in comparison to what they show off on a macroscale, enabling unique programs. For instance, opaque substances can come to be obvious (copper); solid materials can flip flamable (aluminium); insoluble materials might also come to be soluble (gold). A material which includes gold, which is chemically inert at ordinary scales, can serve as a mighty chemical catalyst at nanoscales. Much of the fascination with nanotechnology stems from those quantum and floor phenomena that depend exhibits at the nanoscale.

 Simple to complex : a molecular perspective

Modern synthetic chemistry has reached the factor where it's miles possible to prepare small molecules to almost any structure. These techniques are used nowadays to manufacture a huge kind of useful chemical compounds which include pharmaceuticals or commercial polymers. This capability increases the query of extending this sort of manipulate to the next-large degree, in search of techniques to collect those single molecules into supramolecular assemblies including many molecules organized in a properly defined manner.

These methods utilize the principles of molecular self-meeting and/or supramolecular chemistry to robotically set up themselves into a few beneficial conformation thru a backside-up approach. The idea of molecular reputation is specially essential: molecules can be designed so that a selected configuration or arrangement is preferred because of non-covalent intermolecular forces. The Watson–Crick basepairing policies are an instantaneous end result of this, as is the specificity of an enzyme being centered to a single substrate, or the precise folding of the protein itself. Thus,  or extra components may be designed to be complementary and collectively attractive so they make a greater complex and beneficial entire.

Such bottom-up tactics need to be able to generating devices in parallel and be a great deal cheaper than top-down strategies, but may want to probably be crushed as the size and complexity of the favored meeting will increase. Most beneficial structures require complicated and thermodynamically not likely arrangements of atoms. Nevertheless, there are many examples of self-meeting based on molecular reputation in biology, maximum notably Watson–Crick basepairing and enzyme-substrate interactions. The task for nanotechnology is whether these standards can be used to engineer new constructs further to natural ones.

 Molecular nanotechnology : a long - term view

Molecular nanotechnology, every so often called molecular production, describes engineered nanosystems (nanoscale machines) operating on the molecular scale. Molecular nanotechnology is specially related to the molecular assembler, a machine that could produce a desired shape or device atom-via-atom the usage of the concepts of mechanosynthesis. Manufacturing inside the context of productive nanosystems isn't related to, and ought to be truly prominent from, the conventional technologies used to fabricate nanomaterials such as carbon nanotubes and nanoparticles.

When the term "nanotechnology" changed into independently coined and popularized by Eric Drexler (who at the time become ignorant of an in advance usage by way of Norio Taniguchi) it stated a destiny manufacturing technology based on molecular machine systems. The premise changed into that molecular-scale organic analogies of traditional device components tested molecular machines were feasible: by means of the infinite examples determined in biology, it is regarded that state-of-the-art, stochastically optimized biological machines can be produced.

It is was hoping that traits in nanotechnology will make possible their creation by using some other approach, perhaps using biomimetic ideas. However, Drexler and different researchers have proposed that advanced nanotechnology, even though possibly initially carried out by biomimetic method, in the long run can be primarily based on mechanical engineering concepts, specifically, a manufacturing era based totally on the mechanical functionality of these components (inclusive of gears, bearings, vehicles, and structural contributors) that could allow programmable, positional assembly to atomic specification. The physics and engineering overall performance of exemplar designs were analyzed in Drexler's book Nanosystems.

In wellknown it is very hard to bring together gadgets at the atomic scale, as one has to put atoms on other atoms of comparable length and stickiness. Another view, positioned forth by using Carlo Montemagno, is that destiny nanosystems will be hybrids of silicon technology and biological molecular machines. Richard Smalley argued that mechanosynthesis are impossible because of the difficulties in automatically manipulating individual molecules.

This led to an change of letters inside the ACS guide Chemical & Engineering News in 2003. Though biology definitely demonstrates that molecular machine systems are viable, non-biological molecular machines are nowadays best of their infancy. Leaders in studies on non-biological molecular machines are Dr. Alex Zettl and his colleagues at Lawrence Berkeley Laboratories and UC Berkeley. They have built at the least three awesome molecular devices whose movement is controlled from the computer with converting voltage: a nanotube nanomotor, a molecular actuator, and a nanoelectromechanical rest oscillator. See nanotube nanomotor for more examples.

An test indicating that positional molecular assembly is feasible was done by Ho and Lee at Cornell University in 1999. They used a scanning tunneling microscope to transport an individual carbon monoxide molecule (CO) to an person iron atom (Fe) sitting on a flat silver crystal, and chemically certain the CO to the Fe via applying a voltage.

Current research

Graphical representation of a rotaxane, useful as a molecular switch.

 

Nanomaterials

 

The nanomaterials field includes subfields which broaden or examine substances having unique residences arising from their nanoscale dimensions.

 * Interface and colloid science has given upward thrust to many materials which may be beneficial in nanotechnology, such as carbon nanotubes and different fullerenes, and numerous nanoparticles and nanorods. Nanomaterials with fast ion transport are related also to nanoionics and nanoelectronics.

*  Nanoscale substances also can be used for bulk applications; most gift commercial programs of nanotechnology are of this taste.

* Progress has been made in the use of these materials for scientific programs; see Nanomedicine.

* Nanoscale substances including nanopillars are from time to time used in sun cells which combats the price of traditional silicon sun cells.

*    Development of programs incorporating semiconductor nanoparticles to be used in the subsequent technology of products, which include show generation, lighting fixtures, solar cells and organic imaging; see quantum dots.

* Recent utility of nanomaterials encompass various biomedical applications, together with tissue engineering, drug transport, antibacterials and biosensors.

Bottom-up approaches

This DNA tetrahedron is an artificially designed nanostructure of the sort made within the area of DNA nanotechnology. Each edge of the tetrahedron is a 20 base pair DNA double helix, and every vertex is a 3-arm junction.

 

These are searching for to set up smaller components into more complicated assemblies.

* DNA nanotechnology makes use of the specificity of Watson–Crick basepairing to construct nicely-defined structures out of DNA and other nucleic acids.

* Approaches from the sector of "classical" chemical synthesis (Inorganic and organic synthesis) also aim at designing molecules with well-described shape (e.G. Bis-peptides ).

* More normally, molecular self-assembly seeks to apply ideas of supramolecular chemistry, and molecular recognition in particular, to motive single-molecule additives to mechanically arrange themselves into some useful conformation.

* Atomic force microscope recommendations may be used as a nanoscale "write head" to deposit a chemical upon a floor in a preferred sample in a method known as dip pen nanolithography. This method fits into the bigger subfield of nanolithography.

* Molecular Beam Epitaxy lets in for backside up assemblies of substances, most notably semiconductor substances commonly utilized in chip and computing packages, stacks, gating, and nanowire lasers.

Top-down approaches

This tool transfers electricity from nano-skinny layers of quantum wells to nanocrystals above them, inflicting the nanocrystals to emit seen light.

 These seek to create smaller gadgets through the use of larger ones to direct their assembly.

*  Many technologies that descended from conventional stable-nation silicon strategies for fabricating microprocessors at the moment are capable of developing capabilities smaller than one hundred nm, falling under the definition of nanotechnology. Giant magnetoresistance-primarily based hard drives already available on the market suit this description, as do atomic layer deposition (ALD) techniques. Peter Grünberg and Albert Fert obtained the Nobel Prize in Physics in 2007 for their discovery of Giant magnetoresistance and contributions to the sphere of spintronics.

*  Solid-kingdom techniques also can be used to create gadgets known as nanoelectromechanical systems or NEMS, that are related to microelectromechanical structures or MEMS.

* Focused ion beams can immediately eliminate material, or maybe deposit fabric while suitable precursor gasses are applied on the same time. For instance, this method is used routinely to create sub-100 nm sections of cloth for evaluation in Transmission electron microscopy.

* Atomic pressure microscope pointers may be used as a nanoscale "write head" to deposit a face up to, which is then followed with the aid of an etching system to take away fabric in a top-down technique.

Functional approached

These searching for to develop additives of a favored functionality with out regard to how they is probably assembled.

* Magnetic assembly for the synthesis of anisotropic superparamagnetic substances such as lately supplied magnetic nano chains.

* Molecular scale electronics seeks to broaden molecules with beneficial electronic homes. These ought to then be used as unmarried-molecule components in a nanoelectronic device. For an instance see rotaxane.

* Synthetic chemical techniques can also be used to create artificial molecular motors, together with in a so-referred to as nanocar.

Biomimetic approaches

* Bionics or biomimicry seeks to use organic techniques and systems found in nature, to the have a look at and design of engineering structures and modern-day technology. Biomineralization is one instance of the structures studied.

* Bionanotechnology is using biomolecules for applications in nanotechnology, which includes use of viruses and lipid assemblies. Nanocellulose is a potential bulk-scale application.

Speculative

These subfields are trying to find to anticipate what innovations nanotechnology would possibly yield, or try to suggest an agenda along which inquiry may development. These regularly take a massive-photograph view of nanotechnology, with more emphasis on its societal implications than the details of the way such inventions could in reality be created.

* Molecular nanotechnology is a proposed approach which involves manipulating single molecules in finely controlled, deterministic ways. This is greater theoretical than the alternative subfields, and many of its proposed techniques are beyond cutting-edge abilties.

* Nanorobotics centers on self-enough machines of some functionality running on the nanoscale. There are hopes for making use of nanorobots in medicine. Nevertheless, development on revolutionary materials and methodologies has been proven with a few patents granted about new nanomanufacturing gadgets for destiny business packages, which also step by step helps inside the improvement toward nanorobots with the usage of embedded nanobioelectronics concepts.

* Productive nanosystems are "systems of nanosystems" in an effort to be complicated nanosystems that produce atomically precise components for other nanosystems, no longer necessarily using novel nanoscale-emergent houses, however well-understood basics of producing. Because of the discrete (i.E. Atomic) nature of remember and the possibility of exponential increase, this stage is visible as the basis of every other commercial revolution. Mihail Roco, one of the architects of america's National Nanotechnology Initiative, has proposed 4 states of nanotechnology that appear to parallel the technical development of the Industrial Revolution, progressing from passive nanostructures to energetic nanodevices to complicated nanomachines and in the long run to effective nanosystems.

* Programmable matter seeks to layout materials whose residences can be easily, reversibly and externally managed even though a fusion of records technology and materials science.

* Due to the recognition and media exposure of the time period nanotechnology, the phrases picotechnology and femtotechnology were coined in analogy to it, despite the fact that those are best used hardly ever and informally.

Dimensionality in nanomaterials

Nanomaterials may be categorised in 0D, 1D, 2D and three-D nanomaterials. The dimensionality play a prime position in determining the feature of nanomaterials inclusive of bodily, chemical and biological traits. With the lower in dimensionality, an boom in surface-to-extent ratio is found. This suggest that smaller dimensional nanomaterials have higher surface region as compared to 3D nanomaterials. Recently, two dimensional (2D) nanomaterials are extensively investigated for digital, biomedical, drug shipping and biosensor applications.

Tools and technecique

Typical AFM setup. A microfabricated cantilever with a sharp tip is deflected by capabilities on a sample floor, just like in a phonograph however on a miles smaller scale. A laser beam reflects off the bottom of the cantilever into a set of photodetectors, permitting the deflection to be measured and assembled into an photo of the surface.

 There are numerous important present day traits. The atomic force microscope (AFM) and the Scanning Tunneling Microscope (STM) are  early versions of scanning probes that launched nanotechnology. There are different types of scanning probe microscopy. Although conceptually much like the scanning confocal microscope advanced by means of Marvin Minsky in 1961 and the scanning acoustic microscope (SAM) developed by using Calvin Quate and coworkers inside the Nineteen Seventies, more moderen scanning probe microscopes have a good deal higher resolution, considering that they're now not limited by the wavelength of sound or mild.

The tip of a scanning probe can also be used to control nanostructures (a method referred to as positional meeting). Feature-orientated scanning methodology can be a promising manner to implement those nanomanipulations in automated mode. However, that is nevertheless a slow process because of low scanning pace of the microscope.

Various techniques of nanolithography such as optical lithography, X-ray lithography, dip pen nanolithography, electron beam lithography or nanoimprint lithography have been additionally developed. Lithography is a pinnacle-down fabrication method wherein a bulk cloth is reduced in size to nanoscale sample.

Another organization of nanotechnological techniques encompass those used for fabrication of nanotubes and nanowires, those utilized in semiconductor fabrication which include deep ultraviolet lithography, electron beam lithography, focused ion beam machining, nanoimprint lithography, atomic layer deposition, and molecular vapor deposition, and in addition including molecular self-meeting strategies along with the ones using di-block copolymers. The precursors of those techniques preceded the nanotech generation, and are extensions within the development of clinical advancements as opposed to techniques which have been devised with the sole purpose of creating nanotechnology and which had been outcomes of nanotechnology research.

The pinnacle-down method anticipates nanodevices that need to be built piece by means of piece in tiers, a great deal as manufactured items are made. Scanning probe microscopy is an important technique both for characterization and synthesis of nanomaterials. Atomic pressure microscopes and scanning tunneling microscopes can be used to look at surfaces and to transport atoms round. By designing distinctive recommendations for those microscopes, they can be used for carving out systems on surfaces and to assist guide self-assembling structures. By using, as an instance, feature-orientated scanning method, atoms or molecules may be moved around on a surface with scanning probe microscopy strategies. At present, it's far high-priced and time-eating for mass manufacturing but very suitable for laboratory experimentation.

In comparison, backside-up techniques construct or grow large structures atom by using atom or molecule via molecule. These techniques encompass chemical synthesis, self-assembly and positional assembly. Dual polarisation interferometry is one device suitable for characterisation of self assembled skinny films. Another variant of the lowest-up approach is molecular beam epitaxy or MBE. Researchers at Bell Telephone Laboratories like John R. Arthur. Alfred Y. Cho, and Art C. Gossard evolved and applied MBE as a studies device inside the past due 1960s and 1970s. Samples made by MBE were key to the invention of the fractional quantum Hall effect for which the 1998 Nobel Prize in Physics became awarded. MBE lets in scientists to lay down atomically specific layers of atoms and, inside the technique, increase complicated systems. Important for research on semiconductors, MBE is also widely used to make samples and gadgets for the newly emerging discipline of spintronics.

However, new healing products, based on responsive nanomaterials, together with the ultradeformable, stress-sensitive Transfersome vesicles, are below development and already authorized for human use in a few international locations.

WRITTEN BY : ADRISH WAHEED