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Nanotechnology, shortened to "nanotech", is the study of the controlling of matter on an atomic and molecular scale. Generally nanotechnology deals with structures of the size 100 nanometers or smaller in at least one dimension, and involves developing materials or devices within that size. Nanotechnology is very diverse, ranging from extensions of conventional device physics to completely new approaches based upon molecular self-assembly, from developing new materials with dimensions on the nanoscale to investigating whether we can directly control matter on the atomic scale.

There has been much debate on the future implications of nanotechnology. Nanotechnology has the potential to create many new materials and devices with a vast range of applications, such as in medicine, electronics and energy production. On the other hand, nanotechnology raises many of the same issues as with any introduction of new technology, including concerns about the toxicity and environmental impact of nanomaterials,[1] and their potential effects on global economics, as well as speculation about various doomsday scenarios. These concerns have led to a debate among advocacy groups and governments on whether special regulation of nanotechnology is warranted.

Contents

Origins

Rotating view of Buckminister Fullerene C60.

The first use of the concepts found in 'nano-technology' (but pre-dating use of that name) was in "There's Plenty of Room at the Bottom," a talk given by physicist Richard Feynman at an American Physical Society meeting at Caltech on December 29, 1959. Feynman described a process by which the ability to manipulate individual atoms and molecules might be developed, using one set of precise tools to build and operate another proportionally smaller set, and so on down to the needed scale. In the course of this, he noted, scaling issues would arise from the changing magnitude of various physical phenomena: gravity would become less important, surface tension and van der Waals attraction would become increasingly more significant, etc. This basic idea appeared plausible, and exponential assembly enhances it with parallelism to produce a useful quantity of end products. The term "nanotechnology" was defined by Tokyo Science University Professor Norio Taniguchi in a 1974 paper[2] as follows: "'Nano-technology' mainly consists of the processing of, separation, consolidation, and deformation of materials by one atom or by one molecule." In the 1980s the basic idea of this definition was explored in much more depth by Dr. K. Eric Drexler, who promoted the technological significance of nano-scale phenomena and devices through speeches and the books Engines of Creation: The Coming Era of Nanotechnology (1986) and Nanosystems: Molecular Machinery, Manufacturing, and Computation,[3] and so the term acquired its current sense. Engines of Creation: The Coming Era of Nanotechnology is considered the first book on the topic of nanotechnology. Nanotechnology and nanoscience got started in the early 1980s with two major developments; the birth of cluster science and the invention of the scanning tunneling microscope (STM). This development led to the discovery of fullerenes in 1985 and carbon nanotubes a few years later. In another development, the synthesis and properties of semiconductor nanocrystals was studied; this led to a fast increasing number of metal and metal oxide nanoparticles and quantum dots. The atomic force microscope (AFM or SFM) was invented six years after the STM was invented. In 2000, the United States National Nanotechnology Initiative was founded to coordinate Federal nanotechnology research and development.

Fundamental concepts

One nanometer (nm) is one billionth, or 10−9, of a meter. By comparison, typical carbon-carbon bond lengths, or the spacing between these atoms in a molecule, are in the range 0.12–0.15 nm, and a DNA double-helix has a diameter around 2 nm. On the other hand, the smallest cellular life-forms, the bacteria of the genus Mycoplasma, are around 200 nm in length.

To put that scale in another context, the comparative size of a nanometer to a meter is the same as that of a marble to the size of the earth.[4] Or another way of putting it: a nanometer is the amount a man's beard grows in the time it takes him to raise the razor to his face.[4]

Two main approaches are used in nanotechnology. In the "bottom-up" approach, materials and devices are built from molecular components which assemble themselves chemically by principles of molecular recognition. In the "top-down" approach, nano-objects are constructed from larger entities without atomic-level control.[5]

Areas of physics such as nanoelectronics, nanomechanics and nanophotonics have evolved during the last few decades to provide a basic scientific foundation of nanotechnology.

Simple to complex: a molecular perspective

Modern synthetic chemistry has reached the point where it is possible to prepare small molecules to almost any structure. These methods are used today to manufacture a wide variety of useful chemicals such as pharmaceuticals or commercial polymers. This ability raises the question of extending this kind of control to the next-larger level, seeking methods to assemble these single molecules into supramolecular assemblies consisting of many molecules arranged in a well defined manner.

These approaches utilize the concepts of molecular self-assembly and/or supramolecular chemistry to automatically arrange themselves into some useful conformation through a bottom-up approach. The concept of molecular recognition is especially important: molecules can be designed so that a specific configuration or arrangement is favored due to non-covalent intermolecular forces. The Watson–Crick basepairing rules are a direct result of this, as is the specificity of an enzyme being targeted to a single substrate, or the specific folding of the protein itself. Thus, two or more components can be designed to be complementary and mutually attractive so that they make a more complex and useful whole.

Such bottom-up approaches should be capable of producing devices in parallel and be much cheaper than top-down methods, but could potentially be overwhelmed as the size and complexity of the desired assembly increases. Most useful structures require complex and thermodynamically unlikely arrangements of atoms. Nevertheless, there are many examples of self-assembly based on molecular recognition in biology, most notably Watson–Crick basepairing and enzyme-substrate interactions. The challenge for nanotechnology is whether these principles can be used to engineer new constructs in addition to natural ones.

Molecular nanotechnology: a long-term view

Molecular nanotechnology, sometimes called molecular manufacturing, describes engineered nanosystems (nanoscale machines) operating on the molecular scale. Molecular nanotechnology is especially associated with the molecular assembler, a machine that can produce a desired structure or device atom-by-atom using the principles of mechanosynthesis. Manufacturing in the context of productive nanosystems is not related to, and should be clearly distinguished from, the conventional technologies used to manufacture nanomaterials such as carbon nanotubes and nanoparticles.

When the term "nanotechnology" was independently coined and popularized by Eric Drexler (who at the time was unaware of an earlier usage by Norio Taniguchi) it referred to a future manufacturing technology based on molecular machine systems. The premise was that molecular scale biological analogies of traditional machine components demonstrated molecular machines were possible: by the countless examples found in biology, it is known that sophisticated, stochastically optimised biological machines can be produced.

It is hoped that developments in nanotechnology will make possible their construction by some other means, perhaps using biomimetic principles. However, Drexler and other researchers[6] have proposed that advanced nanotechnology, although perhaps initially implemented by biomimetic means, ultimately could be based on mechanical engineering principles, namely, a manufacturing technology based on the mechanical functionality of these components (such as gears, bearings, motors, and structural members) that would enable programmable, positional assembly to atomic specification.[7] The physics and engineering performance of exemplar designs were analyzed in Drexler's book Nanosystems.

In general it is very difficult to assemble devices on the atomic scale, as all one has to position atoms are other atoms of comparable size and stickiness. Another view, put forth by Carlo Montemagno,[8] is that future nanosystems will be hybrids of silicon technology and biological molecular machines. Yet another view, put forward by the late Richard Smalley, is that mechanosynthesis is impossible due to the difficulties in mechanically manipulating individual molecules.

This led to an exchange of letters in the ACS publication Chemical & Engineering News in 2003.[9] Though biology clearly demonstrates that molecular machine systems are possible, non-biological molecular machines are today only in their infancy. Leaders in research on non-biological molecular machines are Dr. Alex Zettl and his colleagues at Lawrence Berkeley Laboratories and UC Berkeley. They have constructed at least three distinct molecular devices whose motion is controlled from the desktop with changing voltage: a nanotube nanomotor, a molecular actuator,[10] and a nanoelectromechanical relaxation oscillator.[11]

An experiment indicating that positional molecular assembly is possible was performed by Ho and Lee at Cornell University in 1999. They used a scanning tunneling microscope to move an individual carbon monoxide molecule (CO) to an individual iron atom (Fe) sitting on a flat silver crystal, and chemically bound the CO to the Fe by applying a voltage.

Current research

Graphical representation of a rotaxane, useful as a molecular switch.
Sarfus image of a DNA biochip elaborated by bottom-up approach.
This device transfers energy from nano-thin layers of quantum wells to nanocrystals above them, causing the nanocrystals to emit visible light.[12]

Nanomaterials

This includes subfields which develop or study materials having unique properties arising from their nanoscale dimensions.[13]

Bottom-up approaches

These seek to arrange smaller components into more complex assemblies.

Top-down approaches

These seek to create smaller devices by using larger ones to direct their assembly.

Functional approaches

These seek to develop components of a desired functionality without regard to how they might be assembled.

Biomimetic approaches

  • Bionics or biomimicry seeks to apply biological methods and systems found in nature, to the study and design of engineering systems and modern technology. Biomineralization is one example of the systems studied.

Speculative

These subfields seek to anticipate what inventions nanotechnology might yield, or attempt to propose an agenda along which inquiry might progress. These often take a big-picture view of nanotechnology, with more emphasis on its societal implications than the details of how such inventions could actually be created.

  • Molecular nanotechnology is a proposed approach which involves manipulating single molecules in finely controlled, deterministic ways. This is more theoretical than the other subfields and is beyond current capabilities.
  • Nanorobotics centers on self-sufficient machines of some functionality operating at the nanoscale. There are hopes for applying nanorobots in medicine,[18][19][20] but it may not be easy to do such a thing because of several drawbacks of such devices.[21] Nevertheless, progress on innovative materials and methodologies has been demonstrated with some patents granted about new nanomanufacturing devices for future commercial applications, which also progressively helps in the development towards nanorobots with the use of embedded nanobioelectronics concepts.[22][23]
  • Programmable matter based on artificial atoms seeks to design materials whose properties can be easily, reversibly and externally controlled.
  • Due to the popularity and media exposure of the term nanotechnology, the words picotechnology and femtotechnology have been coined in analogy to it, although these are only used rarely and informally.

Tools and techniques

Typical AFM 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. A laser beam reflects off the backside of the cantilever into a set of photodetectors, allowing the deflection to be measured and assembled into an image of the surface.

There are several important modern developments. The atomic force microscope (AFM) and the Scanning Tunneling Microscope (STM) are two early versions of scanning probes that launched nanotechnology. There are other types of scanning probe microscopy, all flowing from the ideas of the scanning confocal microscope developed by Marvin Minsky in 1961 and the scanning acoustic microscope (SAM) developed by Calvin Quate and coworkers in the 1970s, that made it possible to see structures at the nanoscale. The tip of a scanning probe can also be used to manipulate nanostructures (a process called positional assembly). Feature-oriented scanning-positioning methodology suggested by Rostislav Lapshin appears to be a promising way to implement these nanomanipulations in automatic mode. However, this is still a slow process because of low scanning velocity of the microscope. Various techniques of nanolithography such as optical lithography, X-ray lithography dip pen nanolithography, electron beam lithography or nanoimprint lithography were also developed. Lithography is a top-down fabrication technique where a bulk material is reduced in size to nanoscale pattern.

Another group of nanotechnological techniques include those used for fabrication of nanowires, those used in semiconductor fabrication such as deep ultraviolet lithography, electron beam lithography, focused ion beam machining, nanoimprint lithography, atomic layer deposition, and molecular vapor deposition, and further including molecular self-assembly techniques such as those employing di-block copolymers. However, all of these techniques preceded the nanotech era, and are extensions in the development of scientific advancements rather than techniques which were devised with the sole purpose of creating nanotechnology and which were results of nanotechnology research.

The top-down approach anticipates nanodevices that must be built piece by piece in stages, much as manufactured items are made. Scanning probe microscopy is an important technique both for characterization and synthesis of nanomaterials. Atomic force microscopes and scanning tunneling microscopes can be used to look at surfaces and to move atoms around. By designing different tips for these microscopes, they can be used for carving out structures on surfaces and to help guide self-assembling structures. By using, for example, feature-oriented scanning-positioning approach, atoms can be moved around on a surface with scanning probe microscopy techniques. At present, it is expensive and time-consuming for mass production but very suitable for laboratory experimentation.

In contrast, bottom-up techniques build or grow larger structures atom by atom or molecule by molecule. These techniques include chemical synthesis, self-assembly and positional assembly. Another variation of the bottom-up approach is molecular beam epitaxy or MBE. Researchers at Bell Telephone Laboratories like John R. Arthur. Alfred Y. Cho, and Art C. Gossard developed and implemented MBE as a research tool in the late 1960s and 1970s. Samples made by MBE were key to the discovery of the fractional quantum Hall effect for which the 1998 Nobel Prize in Physics was awarded. MBE allows scientists to lay down atomically-precise layers of atoms and, in the process, build up complex structures. Important for research on semiconductors, MBE is also widely used to make samples and devices for the newly emerging field of spintronics.

However, new therapeutic products, based on responsive nanomaterials, such as the ultradeformable, stress-sensitive Transfersome vesicles, are under development and already approved for human use in some countries.[citation needed]

Applications

As of August 21, 2008, the Project on Emerging Nanotechnologies estimates that over 800 manufacturer-identified nanotech products are publicly available, with new ones hitting the market at a pace of 3–4 per week.[24] The project lists all of the products in a publicly accessible online inventory. Most applications are limited to the use of "first generation" passive nanomaterials which includes titanium dioxide in sunscreen, cosmetics and some food products; Carbon allotropes used to produce gecko tape; silver in food packaging, clothing, disinfectants and household appliances; zinc oxide in sunscreens and cosmetics, surface coatings, paints and outdoor furniture varnishes; and cerium oxide as a fuel catalyst.[25]

The National Science Foundation (a major distributor for nanotechnology research in the United States) funded researcher David Berube to study the field of nanotechnology. His findings are published in the monograph Nano-Hype: The Truth Behind the Nanotechnology Buzz. This study concludes that much of what is sold as “nanotechnology” is in fact a recasting of straightforward materials science, which is leading to a “nanotech industry built solely on selling nanotubes, nanowires, and the like” which will “end up with a few suppliers selling low margin products in huge volumes." Further applications which require actual manipulation or arrangement of nanoscale components await further research. Though technologies branded with the term 'nano' are sometimes little related to and fall far short of the most ambitious and transformative technological goals of the sort in molecular manufacturing proposals, the term still connotes such ideas. According to Berube, there may be a danger that a "nano bubble" will form, or is forming already, from the use of the term by scientists and entrepreneurs to garner funding, regardless of interest in the transformative possibilities of more ambitious and far-sighted work.[26]

Nano-membranes have been produced that are portable and easily-cleaned systems that purify, detoxify and desalinate water meaning that third-world countries could get clean water, solving many water related health issues.[27]

Implications

Because of the far-ranging claims that have been made about potential applications of nanotechnology, a number of serious concerns have been raised about what effects these will have on our society if realized, and what action if any is appropriate to mitigate these risks.

There are possible dangers that arise with the development of nanotechnology. The Center for Responsible Nanotechnology suggests that new developments could result, among other things, in untraceable weapons of mass destruction, networked cameras for use by the government, and weapons developments fast enough to destabilize arms races ("Nanotechnology Basics").

One area of concern is the effect that industrial-scale manufacturing and use of nanomaterials would have on human health and the environment, as suggested by nanotoxicology research. Groups such as the Center for Responsible Nanotechnology have advocated that nanotechnology should be specially regulated by governments for these reasons. Others counter that overregulation would stifle scientific research and the development of innovations which could greatly benefit mankind.

Other experts, including director of the Woodrow Wilson Center's Project on Emerging Nanotechnologies David Rejeski, have testified[28] that successful commercialization depends on adequate oversight, risk research strategy, and public engagement. Berkeley, California is currently the only city in the United States to regulate nanotechnology;[29] Cambridge, Massachusetts in 2008 considered enacting a similar law,[30] but ultimately rejected this.[31]

Health and environmental concerns

Some of the recently developed nanoparticle products may have unintended consequences. Researchers have discovered that silver nanoparticles used in socks only to reduce foot odor are being released in the wash with possible negative consequences.[32] Silver nanoparticles, which are bacteriostatic, may then destroy beneficial bacteria which are important for breaking down organic matter in waste treatment plants or farms.[33]

A study at the University of Rochester found that when rats breathed in nanoparticles, the particles settled in the brain and lungs, which led to significant increases in biomarkers for inflammation and stress response.[34] A study in China indicated that nanoparticles induce skin aging through oxidative stress in hairless mice.[35][36]

A major study published more recently in Nature Nanotechnology suggests some forms of carbon nanotubes – a poster child for the “nanotechnology revolution” – could be as harmful as asbestos if inhaled in sufficient quantities. Anthony Seaton of the Institute of Occupational Medicine in Edinburgh, Scotland, who contributed to the article on carbon nanotubes said "We know that some of them probably have the potential to cause mesothelioma. So those sorts of materials need to be handled very carefully.".[37] In the absence of specific nano-regulation forthcoming from governments, Paull and Lyons (2008) have called for an exclusion of engineered nanoparticles from organic food.[38] A newspaper article reports that workers in a paint factory developed serious lung disease and nanoparticles were found in their lungs.[39]

Regulation

Calls for tighter regulation of nanotechnology have occurred alongside a growing debate related to the human health and safety risks associated with nanotechnology. Furthermore, there is significant debate about who is responsible for the regulation of nanotechnology. While some non-nanotechnology specific regulatory agencies currently cover some products and processes (to varying degrees) – by “bolting on” nanotechnology to existing regulations – there are clear gaps in these regimes.[40] In "Nanotechnology Oversight: An Agenda for the Next Administration,"[41] former EPA deputy administrator J. Clarence (Terry) Davies lays out a clear regulatory roadmap for the next presidential administration and describes the immediate and longer term steps necessary to deal with the current shortcomings of nanotechnology oversight.

Stakeholders concerned by the lack of a regulatory framework to assess and control risks associated with the release of nanoparticles and nanotubes have drawn parallels with bovine spongiform encephalopathy (‘mad cow’s disease), thalidomide, genetically modified food,[42] nuclear energy, reproductive technologies, biotechnology, and asbestosis. Dr. Andrew Maynard, chief science advisor to the Woodrow Wilson Center’s Project on Emerging Nanotechnologies, concludes (among others) that there is insufficient funding for human health and safety research, and as a result there is currently limited understanding of the human health and safety risks associated with nanotechnology.[43] As a result, some academics have called for stricter application of the precautionary principle, with delayed marketing approval, enhanced labelling and additional safety data development requirements in relation to certain forms of nanotechnology.[44]

The Royal Society report[45] identified a risk of nanoparticles or nanotubes being released during disposal, destruction and recycling, and recommended that “manufacturers of products that fall under extended producer responsibility regimes such as end-of-life regulations publish procedures outlining how these materials will be managed to minimize possible human and environmental exposure” (p.xiii). Reflecting the challenges for ensuring responsible life cycle regulation, the Institute for Food and Agricultural Standards has proposed standards for nanotechnology research and development should be integrated across consumer, worker and environmental standards. They also propose that NGOs and other citizen groups play a meaningful role in the development of these standards.

In October 2008, the Department of Toxic Substances Control (DTSC), within the California Environmental Protection Agency, announced its intent to request information regarding analytical test methods, fate and transport in the environment, and other relevant information from manufacturers of carbon nanotubes.[46] The purpose of this information request will be to identify information gaps and to develop information about carbon nanotubes, an important emerging nanomaterial.

See also

References

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  2. ^ N. Taniguchi (1974). On the Basic Concept of 'Nano-Technology. Proc. Intl. Conf. Prod. London, Part II British Society of Precision Engineering. 
  3. ^ Eric Drexler (1991). Nanosystems: Molecular Machinery, Manufacturing, and Computation. MIT PhD thesis. New York: Wiley. ISBN 0471575186. http://www.e-drexler.com/d/06/00/Nanosystems/toc.html. 
  4. ^ a b Kahn, Jennifer (2006). "Nanotechnology". National Geographic 2006 (June): 98–119. 
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  6. ^ Nanotechnology: Developing Molecular Manufacturing
  7. ^ "Some papers by K. Eric Drexler". http://www.imm.org/PNAS.html. 
  8. ^ California NanoSystems Institute
  9. ^ C&En: Cover Story - Nanotechnology
  10. ^ Regan, BC; Aloni, S; Jensen, K; Ritchie, RO; Zettl, A (2005). "Nanocrystal-powered nanomotor.". Nano letters 5 (9): 1730–3. doi:10.1021/nl0510659. PMID 16159214. http://www.physics.berkeley.edu/research/zettl/pdf/312.NanoLett5regan.pdf. 
  11. ^ Regan, B. C.; Aloni, S.; Jensen, K.; Zettl, A. (2005). "Surface-tension-driven nanoelectromechanical relaxation oscillator". Applied Physics Letters 86: 123119. doi:10.1063/1.1887827. http://www.lbl.gov/Science-Articles/Archive/sabl/2005/May/Tiniest-Motor.pdf. 
  12. ^ Wireless nanocrystals efficiently radiate visible light
  13. ^ Clarkson, AJ; Buckingham, DA; Rogers, AJ; Blackman, AG; Clark, CR (2004). "Nanostructured Ceramics in Medical Devices: Applications and Prospects". JOM 56 (10): 38–43. doi:10.1007/s11837-004-0289-x. PMID 11196953. 
  14. ^ Levins, Christopher G.; Schafmeister, Christian E. (2006). "The Synthesis of Curved and Linear Structures from a Minimal Set of Monomers.". ChemInform 37. doi:10.1002/chin.200605222. 
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  16. ^ "The Nobel Prize in Physics 2007". Nobelprize.org. http://nobelprize.org/nobel_prizes/physics/laureates/2007/index.html. Retrieved 2007-10-19. 
  17. ^ Das S, Gates AJ, Abdu HA, Rose GS, Picconatto CA, Ellenbogen JC. (2007). "Designs for Ultra-Tiny, Special-Purpose Nanoelectronic Circuits". IEEE Transactions on Circuits and Systems I 54 (11): 2528–2540. doi:10.1109/TCSI.2007.907864. 
  18. ^ Ghalanbor Z, Marashi SA, Ranjbar B (2005). "Nanotechnology helps medicine: nanoscale swimmers and their future applications". Med Hypotheses 65 (1): 198–199. doi:10.1016/j.mehy.2005.01.023. PMID 15893147. 
  19. ^ Kubik T, Bogunia-Kubik K, Sugisaka M. (2005). "Nanotechnology on duty in medical applications". Curr Pharm Biotechnol. 6 (1): 17–33. PMID 15727553. 
  20. ^ Leary, SP; Liu, CY; Apuzzo, ML (2006). "Toward the Emergence of Nanoneurosurgery: Part III-Nanomedicine: Targeted Nanotherapy, Nanosurgery, and Progress Toward the Realization of Nanoneurosurgery". Neurosurgery 58 (6): 1009–1026. doi:10.1227/01.NEU.0000217016.79256.16. PMID 16723880. 
  21. ^ Shetty RC (2005). "Potential pitfalls of nanotechnology in its applications to medicine: immune incompatibility of nanodevices". Med Hypotheses 65 (5): 998–9. doi:10.1016/j.mehy.2005.05.022. PMID 16023299. 
  22. ^ Cavalcanti A, Shirinzadeh B, Freitas RA Jr., Kretly LC. (2007). "Medical Nanorobot Architecture Based on Nanobioelectronics". Recent Patents on Nanotechnology. 1 (1): 1–10. doi:10.2174/187221007779814745. 
  23. ^ Boukallel M, Gauthier M, Dauge M, Piat E, Abadie J. (2007). "Smart microrobots for mechanical cell characterization and cell convoying". IEEE Trans. Biomed. Eng. 54 (8): 1536–40. doi:10.1109/TBME.2007.891171. PMID 17694877. 
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  25. ^ Applications for Nanotechnology
  26. ^ Berube, David. Nano=Hype: The Truth Behind the Nanotechnology Buzz, Amherst, NY: Prometheus Books, 2006
  27. ^ Savage, N., Diallo, M., Duncan, J., eds., Nanotechnology Applications for Clean Water, Norwich, NY: William Andrew Publishing, 2008
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  29. ^ Berkeley considering need for nano safety (Rick DelVecchio, Chronicle Staff Writer) Friday, November 24, 2006
  30. ^ Cambridge considers nanotech curbs - City may mimic Berkeley bylaws (By Hiawatha Bray, Boston Globe Staff)January 26, 2007
  31. ^ Recommendations for a Municipal Health & Safety Policy for Nanomaterials: A Report to the Cambridge City Manager. July 2008.
  32. ^ Lubick, N. (2008). Silver socks have cloudy lining.
  33. ^ Murray R.G.E., Advances in Bacterial Paracrystalline Surface Layers (Eds.: T. J. Beveridge, S. F. Koval). Plenum pp. 3 ± 9. [9]
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  36. ^ Jonaitis, TS; Card, JW; Magnuson, B (2010). "Concerns regarding nano-sized titanium dioxide dermal penetration and toxicity study.". Toxicology letters 192 (2): 268–9. doi:10.1016/j.toxlet.2009.10.007. PMID 19836437. 
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  45. ^ Royal Society and Royal Academy of Engineering (2004). Nanoscience and nanotechnologies: opportunities and uncertainties. http://www.nanotec.org.uk/finalReport.htm. Retrieved 2008-05-18. 
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Further reading

External links


Study guide

Up to date as of January 14, 2010
(Redirected to Topic:Nanotechnology article)

From Wikiversity

Contents

Welcome to the Division of Nanotechnology, a division of Interdisciplinary Studies, the School of Engineering, and the Department of Materials Science.

The Center for Nanotechnology provides a multi-disciplinary approach in cooperation with Engineering and Technology the School of Physics and the Department of Molecular Biology.

Subdivisions and departments

Like divisions, subdivisions and departments are pages in the Topic namespace) and their names start with the "Topic:" prefix. Individual departments can be used by multiple schools. Schools that use (link to) the same department should cooperate to develop the department. Subdivisions are used by large divisions to help organize related departments. Not all divisions have subdivisions. If you need a subdivision in your division, you can use the Template:Subdivision boilerplate template to start a subdivision.

Learning resources and projects

Active participants

Carbon nanotubes.

The histories of Wikiversity pages indicate who the active participants are. If you are an active participant in this division, you can list your name here (this can help small divisions grow and the participants communicate better; for large divisions a list of active participants is not needed).

  • Dr SHOEB82

Division news

  • September 16, 2006 - Division founded!
  • February 26, 2007 - Added some related news items to the department page.

See also

External links

Scholarly papers

Open source software

  • SXM++ - Program to capture data from scanning tunneling microscopes

Related news

Archives

Wikibooks

Up to date as of January 23, 2010

From Wikibooks, the open-content textbooks collection

The Opensource Handbook of Nanoscience and Nanotechnology

Nanotechnology and nanoscience is about controlling and understanding matter on the sub-micrometer and atomic scale.

This wikibook on nanoscience and nanotechnology gathers information about the various tools, methods and systems to provide students, researchers and everyone else an open-source handbook and overview guide to this vast interdisciplinary and expanding field - a book that can be adjusted as new things appear and improved by you!

Chapter 1: Introduction

Why is nanotechnology such a 'hot' subject - and is it more hype than substance? This part gives a brief introduction to the visions of nanotechnology and why so many people are working on it around the world. To help set a perspective there are overview tables with timelines, length scales and information resources.

Chapter 2: Seeing 'Nano'

Microscopes allows us to probe the structure of matter with high spatial resolution, making it possible to see for instance individual atoms with tools such as the scanning tunneling microscope, the atomic force microscope, and the transmission electron microscope. With the related spectroscopic methods, we can study the energy levels in nanosystems. This part gives an overview of the tools and methods used in microscopy and spectroscopy of nanostructures.

Chapter 3: Physics at the Nanoscale

On the nanoscale force that we in everyday life do not consider strong, such as contact adhesion, become much more important. In addition, many things behave in a quantum mechanical way. This chapter looks into the scaling of the forces and fundamental dynamics of matter on the nanoscale.

Development stage: 25% (as of {{{2}}}) Physical Chemistry of Surfaces

  1. Hydrophobic and hydrophilic surfaces
  2. Surface Energy
  3. Surface Diffusion
  4. Mass transport in 1, 2, and 3D

Development stage: 25% (as of {{{2}}}) Background material

  1. Dispersion relations

Chapter 4: Nanomaterials

Many unique nanostructured materials have been made, such as carbon nanotubes that can be mechanically stronger than diamond. This part provides an overview of nanoscale materials such as carbon nanotubes, nanowires, quantum dots and nanoparticles, their unique properties and fabrication methods.

Development stage: 25% (as of {{{2}}}) Overview of Production methods

  1. Commercial suppliers of nanomaterials

Chapter 5: Nanosystems

To understand the novel possibilities in nanotechnology, this part gives an overview of some typical nanoscale systems - simple experimental devices that show unique nanoscale behavior useful in for instance electronics.

Development stage: 25% (as of {{{2}}}) Nanoelectronics

  1. Diffusive and Ballistic Electron Transport
  2. Double barrier systems
  3. Moletronics

Development stage: 25% (as of {{{2}}}) Nanomechanics

  1. Mechanics of beams and cantilevers
  2. The harmonic oscillator

Chapter 6: Nanoengineering

Combining nanodevices into functional units for real life application is a daunting task because making controlled structures with molecularly sized components requires extreme precision and control. Here we look at ways to assemble nanosystems into functional units or working devices with top-down or bottom-up approaches.

See also the Wikibook on Microtechnology which contains information about many fabrication and processing details.

Development stage: 25% (as of {{{2}}}) Top-down and bottom-up approaches

  1. Microfabrication made smaller

Development stage: 25% (as of {{{2}}}) Self assembly

  1. Selfassembled monolayers
  2. Bottom-up chemistry
  3. Molecular engineering

Development stage: 25% (as of {{{2}}}) Lithography

  1. Electron beam lithography (EBL)
  2. Nano imprint lithography (NIL)
  3. Focused Ion Beam (FIB)

Chapter 7: Nano-Bio Introduction

Your body is based on a fantastic amount of biological nanotechnology operating right now in each of your body's cells, which has evolved over aeons to an awesome level of complexity. Much of current nanotechnology research is aimed at bio-applications, such as bio-sensors and biologically active nanoparticles for medical therapy or targeting cancer. This part is an introduction to this cross-disciplinary field.

Development stage: 25% (as of {{{2}}}) Nano-bio Primer

  1. Biological building blocks
  2. Lengths and masses
  3. Cells
  4. Virus
  5. Bacteria
  6. The body

Development stage: 25% (as of {{{2}}}) Biosensors

  1. Typical applications and Analytes
  2. Sensor principles

Development stage: 25% (as of {{{2}}}) Nanomedicine - Targeting diseases

  1. Nanomedicine
  2. Cancer
  3. Magnetic Resonance Imaging (MRI)

Chapter 8: Environmental Nanotechnology

People are very enthusiastic about the visions of nanotechnology, but at the same time there is a natural worry about the environmental issues of the emerging technologies. This area is being increasingly brought into focus to ensure a healthy development.

Chapter 9: Nano and Society


Simple English

Nanotechnology is a part of science and technology about the control of matter on the atomic and molecular scale - this means things that are about 100 nanometers or smaller. Nanotechnology includes making products that use parts this small, such as electronic devices, catalysts, and sensors etc. Nanotechnology is defined as the study of structures between 1 nanometer and 100 nanometers in size. To give you an idea of how small that is, there are as many nanometers in an inch as there are inches in 400 miles.

Contents

Overview

Nanotechnology brings together scientists from many different subjects, such as applied physics, materials science, interface and colloid science, device physics, chemistry, supramolecular chemistry (which refers to the area of chemistry that focuses on the noncovalent bonding interactions of molecules), self-replicating machines and robotics, chemical engineering, mechanical engineering, biology, biological engineering, and electrical engineering

Generally when people talk about nanotechnology, they mean structures of the size 100 nanometers or smaller. There are one million nanometers in a millimeter. Nanotechnology tries to make materials or machines of that size.

People are doing many different types of work in the field of nanotechnology. Most current work looks at making nanoparticles (particles with nanometer size) that have special properties, such as the way they scatter light, absorb X-rays, transport electrical currents or heat, etc. etc. At the more "science fiction" end of the field are attempts to make small copies of bigger machines or really new ideas for structures that make themselves. New materials are possible with nano size structures. It is even possible to work with single atoms.

There has been a lot of discussion about the future of nanotechnology and its dangers. Nanotechnology may be able to invent new materials and instruments which would be very useful, such as in medicine, computers, and making clean electricity (nanotechnology is helping design the next generation of solar panels, and efficient low-energy lighting). On the other hand, nanotechnology is new and there could be unknown problems. For example if the materials are bad for people's health or for nature. They may have a bad effect on the economy or even big natural systems like the Earth itself. Some groups argue that there should be rules about the use of nanotechnology.

The Beginning of Nanotechnology

The first use of the ideas in 'nano-technology' (but before the name was invented) was in "There's Plenty of Room at the Bottom", a talk given by the scientist Richard Feynman at an American Physical Society meeting at Caltech on December 29, 1959. Feynman described a way to move individual atoms and molecules using very small apparatus to build and operate even smaller instruments and so on down to the needed scale. In the course of this, he noted, sometimes problems will appear because of the changes in scale. The weight of things under study would become less important, but for example, surface tension and Van der Waals force would become more important.

Feynman's simple idea seemed possible. The word "nanotechnology" was explained by Tokyo Science University Professor Norio Taniguchi in a 1974 paper. He said that nanotechnology was the work of changing materials by one atom or by one molecule. In the 1980s this idea was studied by Dr. K. Eric Drexler, who spoke and wrote about how important nano-scale events and things are. "Engines of Creation: The Coming Era of Nanotechnology" (1986) is thought to be the first book on nanotechnology. Nanotechnology and nanoscience got started in the early 1980s with two key developments: the start of cluster science and the invention of the scanning tunneling microscope (STM). Soon afterwards, new molecules made of carbon were discovered - first fullerenes in 1986, and carbon nanotubes a few years later. In another development, people studied how to make semiconductor nanocrystals. Many metal oxide nanoparticles are now used as quantum dots (nanoparticles where the behaviour of single electrons becomes important). In 2000, the United States National Nanotechnology Initiative was begun to help develop the science in America.

Important Ideas

One nanometer (nm) is one billionth, or 10-9, of a meter. When two carbon atoms join together to make a molecule the distance between them is in the range of 0.12-0.15 nm, and a DNA double-helix is about 2 nm from one side to the other. On the other hand, the smallest living thing with a cell is a bacteria about 200 nm long.

To understand the scale better, think about the difference between a nanometer and a meter. It is the same size difference as a golf ball and the Earth. Or another way of putting it: a nanometer is the amount that a hair on a man's face grows in the time it takes him to lift his hand to shave. Nails also grow one nanometer per second.

There are two common approaches in the field of nanotechnology. In the "bottom-up" idea, materials and instruments are built from molecules which join together because of their chemistry. In the "top - down" idea, nano-objects are made out of bigger things without trying to move parts of them at the level of atoms.

Top - down (Larger to smaller): a look at the problem based on materials

Some of the laws of physics become more obvious as the system gets smaller. For example the effects of very small movements, as well as quantum mechanical effects, like the “quantum size effect” where electrons in solids move differently for very small sizes of particle. This effect does not come into play by going from macro to micro sizes. However, it becomes the most important thing when working in the nanometer size range. A number of physical (mechanical, electrical, optical, etc.) properties also change when a macroscopic system becomes a microscopic one. One example is the increase in amount of surface area for the volume inside it. This changes how heat and chemicals interact with the material. The new types of interaction in nanosystems are of interest in nanomechanics research. Nanomaterials can be catalysts, i.e. they help chemical reactions happen more easily. This can be very useful for the chemical industry to reduce energy use and production of expensive or toxic by-products, but care has to be taken to avoid catalyzing unwanted reactions, such as in their interaction with biomaterials.

Materials made very small can show different properties which we do not see on a macroscale, this makes some completely new inventions possible. For example, substances which usually stop light become transparent (copper); it becomes possible to burn some materials (aluminum); solids turn into liquids at room temperature (gold); insulators become conductors (silicon). A material such as gold, which does not react with other chemicals at normal scales, can be a powerful chemical catalyst at nanoscales. These special properties which we can only see at the nano scale are one of the most interesting things about nanotechnology.

Bottom - up (Smaller to larger)

Modern scientists can now make small molecules with almost any structure. These techniques are used today to make a wide variety of useful chemicals such as medicines or polymers. This ability lets us ask questions about using this kind of method at a larger level: to try to put these single molecules together into structures containing many molecules organized into a system.

This idea uses molecules that move themselves or organize themselves into some useful structure like building blocks. Here it is very important for molecules to find exactly the other molecules that they should connect with. Molecules can be designed so that a certain structure is more likely to appear, because of the forces between the molecules. The Watson-Crick basepairing rules are a way of doing this, so is the way a lot of enzymes work, or the structures that proteins make. In this way, two or more parts of a structure can be designed to find each other and work together to make a bigger and more useful system.

Such techniques should be able to make a lot of small structures at the same time and much cheaper than top-down methods, but it may be difficult for them to design bigger and more complicated structures. Most useful structures need a lot of atoms, organized into a structure that has a small probability of making itself. But there are many examples of these structures in biology, especially Watson-Crick basepairing and enzyme interactions. The interesting job for nanotechnologists is to use the same techniques to make new systems which do not happen in nature.

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