Nanotechnology Engineering – a Review

Ramaiyan Dhanapal. / Journal of Science / Vol 2 / Issue 1 / 2012 / 13-25.

e ISSN 2277 - 3290 Print ISSN 2277 - 3282 Journal of science ENGINEERING

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NANOTECHNOLOGY ENGINEERING – A REVIEW

Ramaiyan Dhanapal *

1Department of Pharmaceutics, Kakatiya Institute of Pharmaceutical Sciences (KIPS), Pembarthi (V), Hasanparthy (M), Warangal, Andhra Pradesh, India-506 371.

ABSTRACT There is much debate on the future implications of nanotechnology. Nanotechnology may be able to create many new materials and devices with a vast range of applications, such as in medicine, electronics, biomaterials and energy production. On the other hand, nanotechnology raises many of the same issues as any new technology, including concerns about the toxicity and environmental impact of nanomaterials, and their potential effects on global economics, as well as speculation about various doomsday scenarios.

Keywords: Nanotechnology, Nanomedicine, Nanoelectronics, Nanobiomaterials.

INTRODUCTION Nanotechnology is the study of manipulating potential effects on global economics, as well as matter on an atomic and molecular scale. Generally, speculation about various doomsday scenarios. These nanotechnology deals with developing materials, devices, concerns have led to a debate among advocacy groups or other structures possessing at least one dimension sized and governments on whether special regulation of from 1 to 100 nanometres. Quantum mechanical effects nanotechnology is warranted. are important at this quantum-realm scale. Although nanotechnology is a relatively recent Nanotechnology is very diverse, ranging from development in scientific research, the development of its extensions of conventional device physics to completely central concepts happened over a longer period of time. new approaches based upon molecular self-assembly, The emergence of nanotechnology in the 1980s was from developing new materials with dimensions on the caused by the convergence of experimental advances such nanoscale to direct control of matter on the atomic scale. as the invention of the scanning tunneling microscope in Nanotechnology entails the application of fields of 1981 and the discovery of fullerenes in 1985, with the science as diverse as surface science, organic chemistry, elucidation and popularization of a conceptual framework molecular biology, semiconductor physics, for the goals of nanotechnology beginning with the 1986 microfabrication, etc. publication of the book Engines of Creation.

There is much debate on the future implications The scanning tunneling microscope, an of nanotechnology. Nanotechnology may be able to create instrument for imaging surfaces at the atomic level, was many new materials and devices with a vast range of developed in 1981 by Gerd Binnig and Heinrich Rohrer at applications, such as in medicine, electronics, IBM Zurich Research Laboratory, for which they received biomaterials and energy production. On the other hand, the Nobel Prize in Physics in 1986. Fullerenes were nanotechnology raises many of the same issues as any discovered in 1985 by Harry Kroto, Richard Smalley, and new technology, including concerns about the toxicity and Robert Curl, who together won the 1996 Nobel Prize in environmental impact of nanomaterials, and their Chemistry.

Corresponding Author:- Ramaiyan Dhanapal Email:- [email protected]

Ramaiyan Dhanapal. / Journal of Science / Vol 2 / Issue 1 / 2012 / 13-25.

Around the same time, K. Eric Drexler to 100 nm following the definition used by the National developed and popularized the concept of nanotechnology Nanotechnology Initiative in the US. The lower limit is and founded the field of molecular nanotechnology. In set by the size of atoms (hydrogen has the smallest atoms, 1979, Drexler encountered Richard Feynman's 1959 talk which are approximately a quarter of a nm diameter) "There's Plenty of Room at the Bottom". The term since nanotechnology must build its devices from atoms "nanotechnology", originally coined by Norio Taniguchi and molecules. The upper limit is more or less arbitrary in 1974, was unknowingly appropriated by Drexler in his but is around the size that phenomena not observed in 1986 book Engines of Creation: The Coming Era of larger structures start to become apparent and can be Nanotechnology, which proposed the idea of a nanoscale made use of in the nano device. These new phenomena "assembler" which would be able to build a copy of itself make nanotechnology distinct from devices which are and of other items of arbitrary complexity. He also first merely miniaturised versions of an equivalent published the term "grey goo" to describe what might macroscopic device; such devices are on a larger scale happen if a hypothetical self-replicating molecular and come under the description of microtechnology. nanotechnology went out of control. Drexler's vision of nanotechnology is often called "Molecular To put that scale in another context, the Nanotechnology" (MNT) or "molecular manufacturing," comparative size of a nanometer to a meter is the same as and Drexler at one point proposed the term "zettatech" that of a marble to the size of the earth. Or another way of which never became popular. putting it: a nanometer is the amount an average man's beard grows in the time it takes him to raise the razor to In the early 2000s, the field was subject to his face. growing public awareness and controversy, with prominent debates about both its potential implications, Two main approaches are used in exemplified by the Royal Society's report on nanotechnology. In the "bottom-up" approach, materials nanotechnology, as well as the feasibility of the and devices are built from molecular components which applications envisioned by advocates of molecular assemble themselves chemically by principles of nanotechnology, which culminated in the public debate molecular recognition. In the "top-down" approach, nano- between Eric Drexler and Richard Smalley in 2001 and objects are constructed from larger entities without 2003. Governments moved to promote and fund research atomic-level control. into nanotechnology with programs such as the National Nanotechnology Initiative. Areas of physics such as nanoelectronics, nanomechanics, nanophotonics and nanoionics have The early 2000s also saw the beginnings of evolved during the last few decades to provide a basic commercial applications of nanotechnology, although scientific foundation of nanotechnology [4]. these were limited to bulk applications of nanomaterials, such as the Silver Nano platform for using silver Larger to smaller: a materials perspective nanoparticles as an antibacterial agent, nanoparticle-based A number of physical phenomena become transparent sunscreens, and carbon nanotubes for stain- pronounced as the size of the system decreases. These resistant textiles [1-3]. include statistical mechanical effects, as well as quantum mechanical effects, for example the “quantum size effect” Fundamental concepts where the electronic properties of solids are altered with Nanotechnology is the engineering of functional great reductions in particle size. This effect does not come systems at the molecular scale. This covers both current into play by going from macro to micro dimensions. work and concepts that are more advanced. In its original However, quantum effects become dominant when the sense, nanotechnology refers to the projected ability to nanometer size range is reached, typically at distances of construct items from the bottom up, using techniques and 100 nanometers or less, the so called quantum realm. tools being developed today to make complete, high Additionally, a number of physical (mechanical, performance products. electrical, optical, etc.) properties change when compared to macroscopic systems. One example is the increase in One nanometer (nm) is one billionth, or 10−9, of surface area to volume ratio altering mechanical, thermal a meter. By comparison, typical carbon-carbon bond and catalytic properties of materials. Diffusion and lengths, or the spacing between these atoms in a reactions at nanoscale, nanostructures materials and molecule, are in the range 0.12–0.15 nm, and a DNA nanodevices with fast ion transport are generally referred double-helix has a diameter around 2 nm. On the other to nanoionics. Mechanical properties of nanosystems are hand, the smallest cellular life-forms, the bacteria of the of interest in the nanomechanics research. The catalytic genus Mycoplasma, are around 200 nm in length. By activity of nanomaterials also opens potential risks in their convention, nanotechnology is taken as the scale range 1 interaction with biomaterials.

Ramaiyan Dhanapal. / Journal of Science / Vol 2 / Issue 1 / 2012 / 13-25.

Materials reduced to the nanoscale can show molecular scale. Molecular nanotechnology is especially different properties compared to what they exhibit on a associated with the molecular assembler, a machine that macroscale, enabling unique applications. For instance, can produce a desired structure or device atom-by-atom opaque substances become transparent (copper); stable using the principles of mechanosynthesis. Manufacturing materials turn combustible (aluminum); insoluble in the context of productive nanosystems is not related to, materials become soluble (gold). A material such as gold, and should be clearly distinguished from, the which is chemically inert at normal scales, can serve as a conventional technologies used to manufacture potent chemical catalyst at nanoscales. Much of the nanomaterials such as carbon nanotubes and nano fascination with nanotechnology stems from these particles. quantum and surface phenomena that matter exhibits at the nanoscale [5]. When the term "nano technology" was independently coined and popularized by Eric Drexler Simple to complex: a molecular perspective (who at the time was unaware of an earlier usage by Modern synthetic chemistry has reached the Norio Taniguchi) it referred to a future manufacturing point where it is possible to prepare small molecules to technology based on molecular machine systems. The almost any structure. These methods are used today to premise was that molecular scale biological analogies of manufacture a wide variety of useful chemicals such as traditional machine components demonstrated molecular pharmaceuticals or commercial polymers. This ability machines were possible: by the countless examples found raises the question of extending this kind of control to the in biology, it is known that sophisticated, stochastically next-larger level, seeking methods to assemble these optimised biological machines can be produced. single molecules into supramolecular assemblies consisting of many molecules arranged in a well defined It is hoped that developments in nanotechnology manner. will make possible their construction by some other means, perhaps using biomimetic principles. However, These approaches utilize the concepts of Drexler and other researchers have proposed that molecular self-assembly and/or supramolecular chemistry advanced nanotechnology, although perhaps initially to automatically arrange themselves into some useful implemented by biomimetic means, ultimately could be conformation through a bottom-up approach. The concept based on mechanical engineering principles, namely, a of molecular recognition is especially important: manufacturing technology based on the mechanical molecules can be designed so that a specific configuration functionality of these components (such as gears, or arrangement is favored due to non-covalent bearings, motors, and structural members) that would intermolecular forces. The Watson–Crick basepairing enable programmable, positional assembly to atomic rules are a direct result of this, as is the specificity of an specification. The physics and engineering performance enzyme being targeted to a single substrate, or the specific of exemplar designs were analyzed in Drexler's book folding of the protein itself. Thus, two or more Nanosystems. components can be designed to be complementary and mutually attractive so that they make a more complex and In general it is very difficult to assemble devices useful whole. on the atomic scale, as all one has to position atoms on other atoms of comparable size and stickiness. Another Such bottom-up approaches should be capable of view, put forth by Carlo Montemagno, is that future producing devices in parallel and be much cheaper than nanosystems will be hybrids of silicon technology and top-down methods, but could potentially be overwhelmed biological molecular machines. Yet another view, put as the size and complexity of the desired assembly forward by the late Richard Smalley, is that increases. Most useful structures require complex and mechanosynthesis is impossible due to the difficulties in thermodynamically unlikely arrangements of atoms. mechanically manipulating individual molecules. Nevertheless, there are many examples of self-assembly based on molecular recognition in biology, most notably This led to an exchange of letters in the ACS Watson–Crick basepairing and enzyme-substrate publication Chemical & Engineering News in 2003. interactions. The challenge for nanotechnology is whether Though biology clearly demonstrates that molecular these principles can be used to engineer new constructs in machine systems are possible, non-biological molecular addition to natural ones [6]. machines are today only in their infancy. Leaders in research on non-biological molecular machines are Dr. Molecular nanotechnology: a long-term view Alex Zettl and his colleagues at Lawrence Berkeley Molecular nanotechnology, sometimes called Laboratories and UC Berkeley. They have constructed at molecular manufacturing, describes engineered least three distinct molecular devices whose motion is nanosystems (nanoscale machines) operating on the controlled from the desktop with changing voltage: a

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nanotube nanomotor, a molecular actuator, and a Top-down approaches nanoelectromechanical relaxation oscillator. An These seek to create smaller devices by using larger ones experiment indicating that positional molecular assembly to direct their assembly. is possible was performed by Ho and Lee at Cornell  Many technologies that descended from conventional University in 1999. They used a scanning tunneling solid-state silicon methods for fabricating microscope to move an individual carbon monoxide microprocessors are now capable of creating features molecule (CO) to an individual iron atom (Fe) sitting on a smaller than 100 nm, falling under the definition of flat silver crystal, and chemically bound the CO to the Fe nanotechnology. Giant magnetoresistance-based hard by applying a voltage [7]. drives already on the market fit this description, as do atomic layer deposition (ALD) techniques. Peter Current research Grünberg and Albert Fert received the Nobel Prize in Nanomaterials Physics in 2007 for their discovery of Giant The nanomaterials field includes subfields which develop magnetoresistance and contributions to the field of or study materials having unique properties arising from spintronics. their nanoscale dimensions.  Solid-state techniques can also be used to create  Interface and colloid science has given rise to many devices known as nanoelectromechanical systems or materials which may be useful in nanotechnology, such as NEMS, which are related to microelectromechanical carbon nanotubes and other fullerenes, and various systems or MEMS. nanoparticles and nanorods. Nanomaterials with fast ion  Focused ion beams can directly remove material, or transport are related also to nanoionics and even deposit material when suitable pre-cursor gasses are nanoelectronics. applied at the same time. For example, this technique is  Nanoscale materials can also be used for bulk used routinely to create sub-100 nm sections of material applications; most present commercial applications of for analysis in Transmission electron microscopy. nanotechnology are of this flavor.  Atomic force microscope tips can be used as a  Progress has been made in using these materials for nanoscale "write head" to deposit a resist, which is then medical applications; see Nanomedicine. followed by an etching process to remove material in a  Nanoscale materials are sometimes used in solar cells top-down method. which combats the cost of traditional Silicon solar cells  Development of applications incorporating Functional approaches semiconductor nanoparticles to be used in the next These seek to develop components of a desired generation of products, such as display technology, functionality without regard to how they might be lighting, solar cells and biological imaging; see quantum assembled. dots [8]. Molecular scale electronics seeks to develop molecules with useful electronic properties. These could then be Bottom-up approaches used as single-molecule components in a nanoelectronic These seek to arrange smaller components into more device. Synthetic chemical methods can also be used to complex assemblies. create synthetic molecular motors, such as in a so-called  DNA nanotechnology utilizes the specificity of nanocar. Watson–Crick basepairing to construct well-defined Biomimetic approaches structures out of DNA and other nucleic acids.  Bionics or biomimicry seeks to apply biological  Approaches from the field of "classical" chemical methods and systems found in nature, to the study and synthesis (inorganic and organic synthesis) also aim at design of engineering systems and modern technology. designing molecules with well-defined shape (e.g. bis- Biomineralization is one example of the systems studied. peptides).  Bionanotechnology is the use of biomolecules for  More generally, molecular self-assembly seeks to use applications in nanotechnology, including use of viruses. concepts of supramolecular chemistry, and molecular Nanocellulose is a potential bulk-scale application. recognition in particular, to cause single-molecule components to automatically arrange themselves into Speculative some useful conformation. These subfields seek to anticipate what  Atomic force microscope tips can be used as a inventions nanotechnology might yield, or attempt to nanoscale "write head" to deposit a chemical upon a propose an agenda along which inquiry might progress. surface in a desired pattern in a process called dip pen These often take a big-picture view of nanotechnology, nanolithography. This technique fits into the larger with more emphasis on its societal implications than the subfield of nanolithography. details of how such inventions could actually be created.

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 Molecular nanotechnology is a proposed approach The tip of a scanning probe can also be used to which involves manipulating single molecules in finely manipulate nanostructures (a process called positional controlled, deterministic ways. This is more theoretical assembly). Feature-oriented scanning methodology than the other subfields and is beyond current capabilities. suggested by Rostislav Lapshin appears to be a promising way to implement these nanomanipulations in automatic  Nanorobotics centers on self-sufficient machines of mode. However, this is still a slow process because of low some functionality operating at the nanoscale. There are scanning velocity of the microscope. hopes for applying nanorobots in medicine, but it may not be easy to do such a thing because of several drawbacks Various techniques of nanolithography such as of such devices. Nevertheless, progress on innovative optical lithography, X-ray lithography dip pen materials and methodologies has been demonstrated with nanolithography, electron beam lithography or some patents granted about new nanomanufacturing nanoimprint lithography were also developed. devices for future commercial applications, which also Lithography is a top-down fabrication technique where a progressively helps in the development towards bulk material is reduced in size to nanoscale pattern. nanorobots with the use of embedded nanobioelectronics concepts. Another group of nanotechnological techniques include those used for fabrication of nanotubes and  Productive nanosystems are "systems of nanowires, those used in semiconductor fabrication such nanosystems" which will be complex nanosystems that as deep ultraviolet lithography, electron beam produce atomically precise parts for other nanosystems, lithography, focused ion beam machining, nanoimprint not necessarily using novel nanoscale-emergent lithography, atomic layer deposition, and molecular vapor properties, but well-understood fundamentals of deposition, and further including molecular self-assembly manufacturing. Because of the discrete (i.e. atomic) techniques such as those employing di-block copolymers. nature of matter and the possibility of exponential growth, However, all of these techniques preceded the nanotech this stage is seen as the basis of another industrial era, and are extensions in the development of scientific revolution. Mihail Roco, one of the architects of the advancements rather than techniques which were devised USA's National Nanotechnology Initiative, has proposed with the sole purpose of creating nanotechnology and four states of nanotechnology that seem to parallel the which were results of nanotechnology research [11]. technical progress of the Industrial Revolution, progressing from passive nanostructures to active The top-down approach anticipates nanodevices nanodevices to complex nanomachines and ultimately to that must be built piece by piece in stages, much as productive nanosystems. manufactured items are made. Scanning probe microscopy is an important technique both for  Programmable matter seeks to design materials characterization and synthesis of nanomaterials. Atomic whose properties can be easily, reversibly and externally force microscopes and scanning tunneling microscopes controlled though a fusion of information science and can be used to look at surfaces and to move atoms around. materials science. By designing different tips for these microscopes, they can be used for carving out structures on surfaces and to  Due to the popularity and media exposure of the term help guide self-assembling structures. By using, for nanotechnology, the words picotechnology and example, feature-oriented scanning approach, atoms or femtotechnology have been coined in analogy to it, molecules can be moved around on a surface with although these are only used rarely and informally [10]. scanning probe microscopy techniques. At present, it is expensive and time-consuming for mass production but A laser beam reflects off the backside of the very suitable for laboratory experimentation. cantilever into a set of photodetectors, allowing the deflection to be measured and assembled into an image of In contrast, bottom-up techniques build or grow the surface. There are several important modern larger structures atom by atom or molecule by molecule. developments. The atomic force microscope (AFM) and These techniques include chemical synthesis, self- the Scanning Tunneling Microscope (STM) are two early assembly and positional assembly. Dual polarisation versions of scanning probes that launched interferometry is one tool suitable for characterisation of nanotechnology. There are other types of scanning probe self assembled thin films. Another variation of the microscopy, all flowing from the ideas of the scanning bottom-up approach is molecular beam epitaxy or MBE. confocal microscope developed by Marvin Minsky in Researchers at Bell Telephone Laboratories like John R. 1961 and the scanning acoustic microscope (SAM) Arthur. Alfred Y. Cho, and Art C. Gossard developed and developed by Calvin Quate and coworkers in the 1970s, implemented MBE as a research tool in the late 1960s and that made it possible to see structures at the nanoscale. 1970s. Samples made by MBE were key to the discovery

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of the fractional quantum Hall effect for which the 1998 arrangement of nanoscale components await further Nobel Prize in Physics was awarded. MBE allows research. Though technologies branded with the term scientists to lay down atomically precise layers of atoms 'nano' are sometimes little related to and fall far short of and, in the process, build up complex structures. the most ambitious and transformative technological goals Important for research on semiconductors, MBE is also of the sort in molecular manufacturing proposals, the term widely used to make samples and devices for the newly still connotes such ideas. According to Berube, there may emerging field of spintronics. be a danger that a "nano bubble" will form, or is forming already, from the use of the term by scientists and However, new therapeutic products, based on entrepreneurs to garner funding, regardless of interest in responsive nanomaterials, such as the ultradeformable, the transformative possibilities of more ambitious and far- stress-sensitive Transfersome vesicles, are under sighted work [13]. development and already approved for human use in some countries [12]. Implications The Center for Responsible Nanotechnology Applications warns of the broad societal implications of untraceable As of August 21, 2008, the Project on Emerging weapons of mass destruction, networked cameras for use Nanotechnologies estimates that over 800 manufacturer- by the government, and weapons developments fast identified nanotech products are publicly available, with enough to destabilize arms races. new ones hitting the market at a pace of 3–4 per week. Another area of concern is the effect that industrial-scale The project lists all of the products in a publicly manufacturing and use of nanomaterials would have on accessible online database. Most applications are limited human health and the environment, as suggested by to the use of "first generation" passive nanomaterials nanotoxicology research. For these reasons, groups such which includes titanium dioxide in sunscreen, cosmetics, as the Center for Responsible Nanotechnology advocate surface coatings, and some food products; Carbon that nanotechnology be regulated by governments. Others allotropes used to produce gecko tape; silver in food counter that overregulation would stifle scientific research packaging, clothing, disinfectants and household and the development of beneficial innovations. appliances; zinc oxide in sunscreens and cosmetics, surface coatings, paints and outdoor furniture varnishes; Some nanoparticle products may have and cerium oxide as a fuel catalyst. unintended consequences. Researchers have discovered Further applications allow tennis balls to last longer, golf that bacteriostatic silver nanoparticles used in socks to balls to fly straighter, and even bowling balls to become reduce foot odor are being released in the wash. These more durable and have a harder surface. Trousers and particles are then flushed into the waste water stream and socks have been infused with nanotechnology so that they may destroy bacteria which are critical components of will last longer and keep people cool in the summer. natural ecosystems, farms, and waste treatment processes. Bandages are being infused with silver nanoparticles to heal cuts faster. Cars are being manufactured with Public deliberations on risk perception in the US nanomaterials so they may need fewer metals and less and UK carried out by the Center for Nanotechnology in fuel to operate in the future. Video game consoles and Society found that participants were more positive about personal computers may become cheaper, faster, and nanotechnologies for energy applications than for health contain more memory thanks to nanotechnology. applications, with health applications raising moral and Nanotechnology may have the ability to make existing ethical dilemmas such as cost and availability. medical applications cheaper and easier to use in places like the general practitioner's office and at home. Experts, including director of the Woodrow Wilson Center's Project on Emerging Nanotechnologies The National Science Foundation (a major David Rejeski, have testified that successful distributor for nanotechnology research in the United commercialization depends on adequate oversight, risk States) funded researcher David Berube to study the field research strategy, and public engagement. Berkeley, of nanotechnology. His findings are published in the California is currently the only city in the United States to monograph Nano-Hype: The Truth Behind the regulate nanotechnology; Cambridge, Massachusetts in Nanotechnology Buzz. This study concludes that much of 2008 considered enacting a similar law, but ultimately what is sold as “nanotechnology” is in fact a recasting of rejected it. Relevant for both research on and application straightforward materials science, which is leading to a of nanotechnologies, the insurability of nanotechnology is “nanotech industry built solely on selling nanotubes, contested. Without state regulation of nanotechnology, the nanowires, and the like” which will “end up with a few availability of private insurance for potential damages is suppliers selling low margin products in huge volumes." seen as necessary to ensure that burdens are not socialised Further applications which require actual manipulation or implicitly.

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health and safety research, and as a result there is Health and environmental concerns currently limited understanding of the human health and Main articles: Health implications of nanotechnology and safety risks associated with nanotechnology. As a result, Environmental implications of nanotechnology some academics have called for stricter application of the Researchers have found that when rats breathed in precautionary principle, with delayed marketing approval, nanoparticles, the particles settled in the brain and lungs, enhanced labelling and additional safety data which led to significant increases in biomarkers for development requirements in relation to certain forms of inflammation and stress response and that nanoparticle nanotechnology. induce skin aging through oxidative stress in hairless The Royal Society report identified a risk of mice. nanoparticles or nanotubes being released during disposal, destruction and recycling, and recommended that A two-year study at UCLA's School of Public “manufacturers of products that fall under extended Health found lab mice consuming nano-titanium dioxide producer responsibility regimes such as end-of-life showed DNA and chromosome damage to a degree linked regulations publish procedures outlining how these to all the big killers of man, namely cancer, heart disease, materials will be managed to minimize possible human neurological disease and aging. and environmental exposure” (p. xiii). Reflecting the challenges for ensuring responsible life cycle regulation, A major study published more recently in Nature the Institute for Food and Agricultural Standards has Nanotechnology suggests some forms of carbon proposed that standards for nanotechnology research and nanotubes – a poster child for the “nanotechnology development should be integrated across consumer, revolution” – could be as harmful as asbestos if inhaled in worker and environmental standards. They also propose sufficient quantities. Anthony Seaton of the Institute of that NGOs and other citizen groups play a meaningful Occupational Medicine in Edinburgh, Scotland, who role in the development of these standards. contributed to the article on carbon nanotubes said "We know that some of them probably have the potential to The Center for Nanotechnology in Society has cause mesothelioma. So those sorts of materials need to found that people respond differently to nanotechnologies be handled very carefully. In the absence of specific based upon application – with participants in public regulation forthcoming from governments, Paull and deliberations more positive about nanotechnologies for Lyons (2008) have called for an exclusion of engineered energy than health applications – suggesting that any nanoparticles in food. A newspaper article reports that public calls for nano regulations may differ by technology workers in a paint factory developed serious lung disease sector [15]. and nanoparticles were found in their lungs [14]. ENERGY APPLICATIONS OF Regulation NANOTECHNOLOGY Calls for tighter regulation of nanotechnology The past few decades, the fields of science and have occurred alongside a growing debate related to the engineering have been seeking to develop new and human health and safety risks of nanotechnology. There is improved types of energy technologies that have the significant debate about who is responsible for the capability of improving life all over the world. In order to regulation of nanotechnology. Some regulatory agencies make the next leap forward from the current generation of currently cover some nanotechnology products and technology, scientists and engineers have been developing processes (to varying degrees) – by “bolting on” Energy Applications of Nanotechnology. nanotechnology to existing regulations – there are clear Nanotechnology, a new field in science, is any technology gaps in these regimes. Davies (2008) has proposed a that contains components smaller than 100 nanometers. regulatory road map describing steps to deal with these For scale, a single virus particle is about 100 nanometers shortcomings. in width.

Stakeholders concerned by the lack of a An important subfield of nanotechnology related regulatory framework to assess and control risks to energy is nanofabrication. Nanofabrication is the associated with the release of nanoparticles and nanotubes process of designing and creating devices on the have drawn parallels with bovine spongiform nanoscale. Creating devices smaller than 100 nanometers encephalopathy ("mad cow" disease), thalidomide, opens many doors for the development of new ways to genetically modified food, nuclear energy, reproductive capture, store, and transfer energy. The inherent level of technologies, biotechnology, and asbestosis. Dr. Andrew control that nanofabrication could give scientists and Maynard, chief science advisor to the Woodrow Wilson engineers would be critical in providing the capability of Center’s Project on Emerging Nanotechnologies, solving many of the problems that the world is facing concludes that there is insufficient funding for human

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today related to the current generation of energy this newer, energy efficient technology closer to technologies. commercialization, and (b.) a novel way to clean most all contaminated forms of water called NanoClear. By using People in the fields of science and engineering the selectivity of this hermetic, engineered composite have already begun developing ways of utilizing material it can transfer only a water molecule from one nanotechnology for the development of consumer face of the membrane to the other leaving behind the products. Benefits already observed from the design of contaminants. It should also be noted Dais received a US these products are an increased efficiency of lighting and Patent (Patent Number 7,990,679) in October 2011 titled heating, increased electrical storage capacity, and a "Nanoparticle Ultracapacitor". This patented item again decrease in the amount of pollution from the use of uses the selectively engineered material to create an energy. Benefits such as these make the investment of energy storage mechanism projected to have performance capital in the research and development of and cost advantages over existing storage technologies. nanotechnology a top priority [16]. The company has used this patent's concepts to create a functional energy storage prototype device named Consumer products NanoCap. NanoCap is a form of ultra-capacitor Recently, previously established and entirely potentially useful to power a broad range of applications new companies such as BetaBatt, Inc. and Oxane including most forms of transportation, energy storage Materials are focusing on nanomaterials as a way to (especially useful as a storage media for renewable energy develop and improve upon older methods for the capture, technologies), telecommunication infrastructure, transfer, and storage of energy for the development of transistor gate dielectrics, and consumer battery consumer products. applications (cell phones, computers, etc.).

ConsERV, a product developed by the Dais A New York based company called Applied Analytic Corporation, uses nanoscale polymer membranes NanoWorks, Inc. has been developing a consumer to increase the efficiency of heating and cooling systems product that utilizes LED technology to generate light. and has already proven to be a lucrative design. The Light-emitting diodes or LEDs, use only about 10% of the polymer membrane was specifically configured for this energy that a typical incandescent or fluorescent light application by selectively engineering the size of the bulb uses and typically last much longer, which makes pores in the membrane to prevent air from passing, while them a viable alternative to traditional light bulbs. While allowing moisture to pass through the membrane. LEDs have been around for decades, this company and ConsERV's value is demonstrated in the form of an others like it have been developing a special variant of energy recovery a device which pretreats the incoming LED called the white LED. White LEDs consist of semi- fresh air to a building using the energy found in the conducting organic layers that are only about 100 exhaust air steam using no moving parts to lower the nanometers in distance from each other and are placed energy and carbon footprint of existing forms of heating between two electrodes, which create an anode, and a and cooling equipment Polymer membranes can be cathode. When voltage is applied to the system, light is designed to selectively allow particles of one size and generated when electricity passes through the two organic shape to pass through while preventing others of different layers. This is called electroluminescence. The dimensions. This makes for a powerful tool that can be semiconductor properties of the organic layers are what used in all markets - consumer, commercial, industrial, allow for the minimal amount of energy necessary to and government products from biological weapons generate light. In traditional light bulbs, a metal filament protection to industrial chemical separations. Dais's near is used to generate light when electricity is run through term uses of this 'family' of selectively engineered the filament. Using metal generates a great deal of heat nanotechnology materials, aside from ConsERV, include and therefore lowers efficiency. (a.) a completely new cooling cycle capable of replacing the refrigerant based cooling cycle the world has known Research for longer lasting batteries has been an for the past 100 plus years. This product, under- ongoing process for years. Researchers have now begun development, is named NanoAir. NanoAir uses only to utilize nanotechnology for battery technology. mPhase water and this selectively engineered membrane material Technologies in conglomeration with Rutgers University to cool (or heat) and dehumidify (or humidify) air. There and Bell Laboratories have utilized nanomaterials to alter are no fluorocarbon producing gasses used, and the the wetting behavior of the surface where the liquid in the energy required to cool a space drops as thermodynamics battery lies to spread the liquid droplets over a greater does the actual cooling. The company was awarded an area on the surface and therefore have greater control over Advanced Research Program Administration - Energy the movement of the droplets. This gives more control to award in 2010, and a United States Department of the designer of the battery. This control prevents reactions Defense (DoD) grant in 2011 both designed to accelerate in the battery by separating the electrolytic liquid from the

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anode and the cathode when the battery is not in use and polymer membranes are also much more efficient in ionic joining them when the battery is in need of use. conductivity. This improves the efficiency of the system and decreases the time between replacements, which Thermal applications also are a future lowers costs. applications of nanothechonlogy creating low cost system of heating, ventilation, and air conditioning, changing Another problem with contemporary fuel cells is molecular structure for better management of temperature the storage of the fuel. In the case of hydrogen fuel cells, [17]. storing the hydrogen in gaseous rather than liquid form improves the efficiency by 5%. However, the materials Economic benefits that we currently have available to us significantly limit The relatively recent shift toward using fuel storage due to low stress tolerance and costs. nanotechnology with respect to the capture, transfer, and Scientists have come up with an answer to this by using a storage of energy has and will continue to have many nanoporous styrene material (which is a relatively positive economic impacts on society. The control of inexpensive material) that when super-cooled to around - materials that nanotechnology offers to scientists and 196oC, naturally holds on to hydrogen atoms and when engineers of consumer products is one of the most heated again releases the hydrogen for use [18]. important aspects of nanotechnology. This allows for an improved efficiency of products across the board. Capacitors: then and now For decades, scientists and engineers have been A major issue with current energy generation is attempting to make computers smaller and more efficient. the loss of efficiency from the generation of heat as a by- Crucial components of computers are capacitors. A product of the process. A common example of this is the capacitor is a device that is made of a pair of electrodes heat generated by the internal combustion engine. The separated by an insulator that each stores an opposite internal combustion engine loses about 64% of the energy charge. A capacitor stores a charge when it is removed from gasoline as heat and an improvement of this alone from the circuit that it is connected to; the charge is could have a significant economic impact. However, released when it is replaced back into the circuit. improving the internal combustion engine in this respect Capacitors have an advantage over batteries in that they has proven to be extremely difficult without sacrificing release their charge much more quickly than a battery. performance. Improving the efficiency of fuel cells through the use of nanotechnology appears to be more Traditional or foil capacitors are composed of plausible by using molecularly tailored catalysts, polymer thin metal conducting plates separated by an electrical membranes, and improved fuel storage. insulator, which are then stacked or rolled and placed in a casing. The problem with a traditional capacitor such as In order for a fuel cell to operate, particularly of this is that they limit how small an engineer can design a the hydrogen variant, a noble-metal catalyst (usually computer. Scientists and engineers have since turned to platinum, which is very expensive) is needed to separate nanotechnology for a solution to the problem. the electrons from the protons of the hydrogen atoms. However, catalysts of this type are extremely sensitive to Using nanotechnology, researchers developed carbon monoxide reactions. In order to combat this, what they call “ultracapacitors.” An ultracapacitor is a alcohols or hydrocarbons compounds are used to lower general term that describes a capacitor that contains the carbon monoxide concentration in the system. This nanocomponents. Ultracapacitors are being researched adds an additional cost to the device. Using heavily because of their high density interior, compact nanotechnology, catalysts can be designed through size, reliability, and high capacitance. This decrease in nanofabrication that are much more resistant to carbon size makes it increasingly possible to develop much monoxide reactions, which improves the efficiency of the smaller circuits and computers. Ultracapacitors also have process and may be designed with cheaper materials to the capability to supplement batteries in hybrid vehicles additionally lower costs. by providing a large amount of energy during peak acceleration and allowing the battery to supply energy Fuel cells that are currently designed for over longer periods of time, such as during a constant transportation need rapid start-up periods for the driving speed. This could decrease the size and weight of practicality of consumer use. This process puts a lot of the large batteries needed in hybrid vehicles as well as strain on the traditional polymer electrolyte membranes, take additional stress off the battery. However, as of now, which decreases the life of the membrane requiring the combination of ultracapacitors and a battery is not frequent replacement. Using nanotechnology, engineers cost effective due to the need of additional DC/DC have the ability to create a much more durable polymer electronics to coordinate the two. membrane, which addresses this problem. Nanoscale

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Nanoporous carbon aerogel is one type of carbon nanotubes. As briefly mentioned before, carbon material that is being utilized for the design of nanotubes are an increasing form of capacitors due to ultracapacitors. These aerogels have a very large interior their superb chemical stability, high conductivity, light surface area and can have its properties altered by mass, and their large surface area. These researchers changing the pore diameter and distribution along with fluorinated single-walled carbon nanotubes (SWCNTs) at adding nanosized alkali metals to alter its conductivity. high temperatures to bind fluorine atoms to the walls. The attached fluorine atoms changed the non-polar nanotubes Carbon nanotubes are another possible material to become polar molecules. This can be attributed to the for use in an ultracapacitor. Carbon nanotubes are created charge transfer from the fluorine. This created dipole- by vaporizing carbon and allowing it to condense on a dipole layers along the carbon nanotube walls. Testing of surface. When the carbon condenses, it forms a nanosized these fluorinated SWCNTs against normal state SWCNTs tube composed of carbon atoms. This tube has a high showed a difference in capacitance. It was determined surface area, which increases the amount of charge that that the fluorinated SWCNTs are advantageous in can be stored. The low reliability and high cost of using fabricating electrodes for capacitors and improve the carbon nanotubes for ultracapacitors is currently an issue wettability with aqueous electrolytes, which promotes the of research. overall performance of supercapacitors. While this study brought to knowledge a more efficient example of In a study concerning ultracapacitors or capacitors, little is known about this new supercapacitor, supercapacitors, researchers at the Sungkyunkwan large scale synthesis is lacking and is necessary for any University in the Republic of Korea explored the massive production, and preparation conditions are quite possibility of increasing the capacitance of electrodes tedious in achieving the final product [19]. through the addition of fluorine atoms to the walls of

Fig 1. Image of reconstruction on a clean Gold(100) surface, as visualized using scanning tunneling microscopy The positions of the individual atoms composing the surface are visible.Main article: Nanomaterials

Fig 2. Graphical representation of a rotaxane, useful as a molecular switch

Ramaiyan Dhanapal. / Journal of Science / Vol 2 / Issue 1 / 2012 / 13-25.

Fig 3. This DNA tetrahedron is an artificially designed nanostructure of the type made in the field of DNA nanotechnology. Each edge of the tetrahedron is a 20 base pair DNA double helix, and each vertex is a three-arm junction

Fig 4. This device transfers energy from nano-thin layers of quantum wells to nanocrystals above them, causing the nanocrystals to emit visible light

Fig 5. Typical atomic force microscope setup. A microfabricated cantilever with a sharp tip is deflected by features on a sample surface, much like in a phonograph but on a much smaller scale

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Fig 6. One of the major applications of nanotechnology is in the area of nanoelectronics with MOSFET's being made of small nanowires ~10 nm in length. Here is a simulation of such a nanowire

CONCLUSION Understanding the concept of capacitance can be Using carbon nanotubes as an example, a helpful in understanding why nanotechnology is such a property of carbon nanotubes is that they have a very high powerful tool for the design of higher energy storing surface area to store a charge. Using the above capacitors. A capacitor’s capacitance (C) or amount of proportionality that capacitance (C) is proportional to the energy stored is equal to the amount of charge (Q) stored surface area (A) of the conducting plate; it becomes on each plate divided by the voltage (V) between the obvious that using nanoscaled materials with high surface plates. Another representation of capacitance is that area would be great for increasing capacitance. The other capacitance (C) is approximately equal to the permittivity proportionality described above is that capacitance (C) is (ε) of the dielectric times the area (A) of the plates inversely proportional to the distance (d) between the divided by the distance (d) between them. Therefore, plates. Using nanoscaled plates such as carbon nanotubes capacitance is proportional to the surface area of the with nanofabrication techniques, gives the capability of conducting plate and inversely proportional to the decreasing the space between plates which again distance between the plates. increases capacitance.

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