PesWiki.com

Menu

PowerPedia:Nanotechnology

Lasted edited by Andrew Munsey, updated on June 14, 2016 at 9:17 pm.

  • 151 errors has been found on this page. Administrator will correct this soon.
  • This page has been imported from the old peswiki website. This message will be removed once updated.

This article may need to be wikified to meet PESWiki's quality standards.Please help improve this article

There was an error working with the wiki: Code[11] known as There was an error working with the wiki: Code[47]s. Members of the fullerene family are a major subject of research falling under the nanotechnology umbrella.]]

Nanotechnology is a field of applied science and technology covering a broad range of topics. The main unifying theme is the control of matter on a scale smaller than 1 micrometer, as well as the fabrication of devices on this same length scale. It is a highly There was an error working with the wiki: Code[16] field, drawing from fields such as There was an error working with the wiki: Code[17], and There was an error working with the wiki: Code[48]. Much speculation exists as to what new science and technology might result from these lines of research. Some view nanotechnology as a marketing term that describes pre-existing lines of research applied to the sub-micron size scale.

Despite the apparent simplicity of this definition, nanotechnology actually encompasses diverse lines of inquiry. Nanotechnology cuts across many disciplines, including There was an error working with the wiki: Code[18] and There was an error working with the wiki: Code[19] components which There was an error working with the wiki: Code[20] chemically using principles of There was an error working with the wiki: Code[49] the other being a "top-down" approach where nano-objects are constructed from larger entities without atomic-level control.

The impetus for nanotechnology has stemmed from a renewed interest in colloidal science, coupled with a new generation of analytical tools such as the There was an error working with the wiki: Code[50] (AFM) and the There was an error working with the wiki: Code[51] (STM). Combined with refined processes such as There was an error working with the wiki: Code[52] and There was an error working with the wiki: Code[53], these instruments allow the deliberate manipulation of nanostructures, and in turn led to the observation of novel phenomena. The manufacture of polymers based on molecular structure, or the design of computer chip layouts based on surface science are examples of nanotechnology in modern use. Despite the great promise of numerous nanotechnologies such as quantum dots and nanotubes, real applications that have moved out of the lab and into the marketplace have mainly utilized the advantages of colloidal nanoparticles in bulk form, such as There was an error working with the wiki: Code[54], There was an error working with the wiki: Code[55], There was an error working with the wiki: Code[56], and stain resistant clothing.

Origins

There was an error working with the wiki: Code[1]

The first mention of some of the distinguishing concepts in nanotechnology (but predating use of that name) was in "There was an error working with the wiki: Code[57]," a talk given by physicist There was an error working with the wiki: Code[58] at an There was an error working with the wiki: Code[59] meeting at There was an error working with the wiki: Code[60] on There was an error working with the wiki: Code[61], There was an error working with the wiki: Code[62]. 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, 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 more important, etc. This basic idea appears feasible, and There was an error working with the wiki: Code[63] enhances it with There was an error working with the wiki: Code[64] to produce a useful quantity of end products.

The term "nanotechnology" was defined by There was an error working with the wiki: Code[21], who promoted the technological significance of nano-scale phenomena and devices through speeches and the books There was an error working with the wiki: Code[65] and Nanosystems: Molecular Machinery, Manufacturing, and Computation, (ISBN 0-471-57518-6), and so the term acquired its current sense.

Nanotechnology and nanoscience got started in the early 1980s with two major developments the birth of There was an error working with the wiki: Code[22] science and the invention of the There was an error working with the wiki: Code[66] (STM). This development led to the discovery of There was an error working with the wiki: Code[67] in 1986 and There was an error working with the wiki: Code[68] a few years later. In another development, the synthesis and properties of semiconductor There was an error working with the wiki: Code[69]s was studied. This led to a fast increasing number of metal oxide nanoparticles of There was an error working with the wiki: Code[70].

Fundamental concepts

There was an error working with the wiki: Code[2]

One nanometer (nm) is one billionth, or 10-9 of a meter. For comparison, typical carbon-carbon There was an error working with the wiki: Code[23] lifeforms, the bacteria of the genus There was an error working with the wiki: Code[71], are around 200 nm in length.

Larger to smaller: a materials perspective

There was an error working with the wiki: Code[24] on a clean There was an error working with the wiki: Code[25](There was an error working with the wiki: Code[26]) surface, as visualized using There was an error working with the wiki: Code[72]. The individual Atoms composing the surface are visible.]]

There was an error working with the wiki: Code[3]

A unique aspect of nanotechnology is the vastly increased ratio of surface area to volume present in many nanoscale materials which opens new possibilities in surface-based science, such as There was an error working with the wiki: Code[27] effects, as well as Quantum mechanics effects, for example the “There was an error working with the wiki: Code[73] size effect? where the electronic properties of solids are altered with great reductions in particle size. This effect does not come into play by going from macro to micro dimensions. However, it becomes dominant when the nanometer size range is reached. Additionally, a number of There was an error working with the wiki: Code[74] change when compared to macroscopic systems. One example is the increase in surface area to volume of materials. This catalytic activity also opens potential risks in their interaction with There was an error working with the wiki: Code[75]s.

Materials reduced to the nanoscale can suddenly show very different properties compared to what they exhibit on a macroscale, enabling unique applications. For instance, opaque substances become transparent (copper) inert materials become catalysts (platinum) stable materials turn combustible (aluminum) solids turn into liquids at room temperature (gold) insulators become conductors (silicon). Materials such as There was an error working with the wiki: Code[76], which is chemically inert at normal scales, can serve as a potent chemical There was an error working with the wiki: Code[77] at nanoscales. Much of the fascination with nanotechnology stems from these unique quantum and surface phenomena that matter exhibits at the nanoscale.

Simple to complex: a molecular perspective

There was an error working with the wiki: Code[4]

Modern There was an error working with the wiki: Code[28] has reached the point where it is possible to prepare small There was an error working with the wiki: Code[29] or commercial There was an error working with the wiki: Code[30] consisting of many molecules arranged in a well defined manner.

These approaches utilize the concepts of There was an error working with the wiki: Code[31] There was an error working with the wiki: Code[32] rules are a direct result of this, as is the specificity of an There was an error working with the wiki: Code[33], or the specific There was an error working with the wiki: Code[34] 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, broadly speaking, be able to produce devices in parallel and 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. The basic laws of probability and entropy make it difficult to self-assemble molecules in useful configurations. Nevertheless, there are many examples of self-assembly based on molecular recognition in There was an error working with the wiki: Code[35] and There was an error working with the wiki: Code[36] interactions. The challenge for nanotechnology is whether these principles can be used to engineer novel constructs in addition to natural ones.

Molecular Nanotechnology: a long-term view

There was an error working with the wiki: Code[5]

Molecular nanotechnology, sometimes called molecular manufacturing, is a term given to the concept of engineered nanosystems (nanoscale machines) operating on the molecular scale. It is especially associated with the concept of a There was an error working with the wiki: Code[37] and There was an error working with the wiki: Code[78] in popular culture, these belong in the realm of science fiction are are not possible with any technology currently foreseeable.

When the term "nanotechnology" was independently coined and popularized by There was an error working with the wiki: Code[38] by There was an error working with the wiki: Code[79]) 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 that molecular machines were possible: by the countless examples found in biology, it is known that billions of years of evolutionary feedback can produce sophisticated, There was an error working with the wiki: Code[80]ally optimized biological machines. It is hoped that developments in nanotechnology will make possible their construction by some other means, perhaps using There was an error working with the wiki: Code[81] principles. However, Drexler and other researchers 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 (PNAS-1981). The physics and engineering performance of exemplar designs were analyzed in Drexler's book Nanosystems. But Drexler's analysis is very qualitative and does not address very pressing issues, such as the "fat fingers" and "Sticky fingers" problems. In general it is not possible to assemble devices on the atomic scale, as all one has to position atoms are other atoms of comparable size and stickyness. Drexler also glosses over the numerical challenges to nano-construction-- assembling just one mole's worth of nanodevices at the rate of a billion atoms per second would take 19 million years.

Another view, put forth by Carlo Montemagno, is that future nanosystems will be hybrids of silicon technology and biological molecular machines. Yet another view, put forward by the late There was an error working with the wiki: Code[39] publication There was an error working with the wiki: Code[82] in 2003.

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 There was an error working with the wiki: Code[83], a molecular actuator, and a nanoelectromechanical relaxation oscillator. 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

There was an error working with the wiki: Code[12] on a surface, using There was an error working with the wiki: Code[84] as wheels.]]

There was an error working with the wiki: Code[13], useful as a molecular switch.]]

There was an error working with the wiki: Code[14]s to There was an error working with the wiki: Code[85]s above them, causing the nanocrystals to emit visible light. ]

As nanotechnology is a very broad term, there are many disparate but sometimes overlapping subfields that could fall under its umbrella. The following avenues of research could be considered subfields of nanotechnology. Note that these categories are fairly nebulous and a single subfield may overlap many of them, especially as the field of nanotechnology continues to mature.

Nanomaterials

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

There was an error working with the wiki: Code[86] science has given rise to many materials which may be useful in nanotechnology, such as There was an error working with the wiki: Code[87]s and other There was an error working with the wiki: Code[88]s, and various There was an error working with the wiki: Code[89]s and There was an error working with the wiki: Code[90]s.

There was an error working with the wiki: Code[40] can also be used for bulk applications most present commercial applications of nanotechnology are of this flavor.

Headway has been made in using these materials for medical applications see There was an error working with the wiki: Code[91].

Bottom-up approaches

These seek to arrange smaller components into more complex assemblies.

DNA Nanotechnology utilizes the specificity of There was an error working with the wiki: Code[41] to construct well-defined structures out of There was an error working with the wiki: Code[92] and other There was an error working with the wiki: Code[93]s.

More generally, There was an error working with the wiki: Code[94] seeks to use concepts of There was an error working with the wiki: Code[95], and There was an error working with the wiki: Code[96] in particular, to cause single-molecule components to automatically arrange themselves into some useful conformation.

Top-down approaches

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

Many technologies descended from conventional There was an error working with the wiki: Code[42] for fabricating There was an error working with the wiki: Code[97]s are now capable of creating features smaller than 100 nm, falling under the definition of nanotechnology. There was an error working with the wiki: Code[98]-based hard drives already on the market fit this description, as do [[atomic layer deposition] (ALD) techniques.

Solid-state techniques can also be used to create devices known as There was an error working with the wiki: Code[99] or NEMS, which are related to There was an error working with the wiki: Code[100] or MEMS.

There was an error working with the wiki: Code[101] tips can be used as a nanoscale "write head" to deposit a chemical on a surface in a desired pattern in a process called There was an error working with the wiki: Code[102]. This fits into the larger subfield of There was an error working with the wiki: Code[103].

Functional approaches

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

There was an error working with the wiki: Code[104] seeks to develop molecules with useful electronic properties. These could then be used as single-molecule components in a nanoelectronic device. For an example see There was an error working with the wiki: Code[105].

Synthetic chemical methods can also be used to create There was an error working with the wiki: Code[106], such as in a so-called There was an error working with the wiki: Code[107].

Speculative

These subfields seek to There was an error working with the wiki: Code[43] 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 There was an error working with the wiki: Code[44] than the details of how such inventions could actually be created.

There was an error working with the wiki: Code[108] 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.

There was an error working with the wiki: Code[109] centers on self-sufficient machines of some functionality operating at the nanoscale.

There was an error working with the wiki: Code[110] based on There was an error working with the wiki: Code[111]s seeks to design materials whose properties can be easily and reversibly externally controlled.

Due to the popularity and media exposure of the term nanotechnology, the words There was an error working with the wiki: Code[112] and There was an error working with the wiki: Code[113] have been coined in analogy to it, although these are only used rarely and informally.

Tools and techniques

There was an error working with the wiki: Code[15] setup. A There was an error working with the wiki: Code[45] There was an error working with the wiki: Code[114] with a sharp tip is deflected by features on a sample surface, much like in a There was an error working with the wiki: Code[115] but on a much smaller scale. A There was an error working with the wiki: Code[116] beam reflects off the backside of the cantilever into a set of There was an error working with the wiki: Code[117]s, allowing the deflection to be measured and assembled into an image of the surface.]]

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.

Nanoscience and nanotechnology only became possible in the 1910s with the development of the first tools to measure and make nanostructures. But the actual development started with the discovery of electrons and neutrons which showed scientists that matter can really exist on a much smaller scale than what we normally think of as small, and/or what they thought was possible at the time. It was at this time when curiosity for nanostructures had originated.

The There was an error working with the wiki: Code[118] (AFM) and the There was an error working with the wiki: Code[119] (STM) are two early versions of scanning probes that launched nanotechnology. There are other types of There was an error working with the wiki: Code[120], all flowing from the ideas of the scanning There was an error working with the wiki: Code[121] developed by There was an error working with the wiki: Code[122] in 1961 and the There was an error working with the wiki: Code[123] (SAM) developed by There was an error working with the wiki: Code[124] 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). However, this is a very slow process. This led to the development of various techniques of There was an error working with the wiki: Code[125] such as There was an error working with the wiki: Code[126], There was an error working with the wiki: Code[127] or There was an error working with the wiki: Code[128]. Lithography is a top-down fabrication technique where a bulk material is reduced in size to nanoscale pattern.

The top-down approach anticipates nanodevices that must be built piece by piece in stages, much as manufactured items are currently made. There was an error working with the wiki: Code[129] is an important technique both for characterization and synthesis of nanomaterials. There was an error working with the wiki: Code[130]s and There was an error working with the wiki: Code[131]s 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. Atoms can be moved around on a surface with scanning probe microscopy techniques, but it is cumbersome, expensive and very time-consuming. For these reasons, it is not feasible to construct nanoscaled devices atom by atom. Assembling a billion transistor microchips at the rate of about one transistor an hour is inefficient.

In contrast, bottom-up techniques build or grow larger structures atom by atom or molecule by molecule. These techniques include There was an error working with the wiki: Code[132], There was an error working with the wiki: Code[133] and positional assembly. Another variation of the bottom-up approach is There was an error working with the wiki: Code[134] or MBE. Researchers at There was an error working with the wiki: Code[135] 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 to the discovery of the fractional quantum Hall effect for which the There was an error working with the wiki: Code[136] There was an error working with the wiki: Code[137] 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 There was an error working with the wiki: Code[138].

Newer techniques such as There was an error working with the wiki: Code[139] are enabling scientists to measure quantitatively the molecular interactions that take place at the nano-scale.

Applications

There was an error working with the wiki: Code[6]

Although there has been much hype about the potential applications of nanotechnology, most current commercialized applications are limited to the use of nanomaterials in bulk, for example the use of titanium dioxide nanoparticles to make transparent sunscreen. Further applications which require actual manipulation or arrangement of nanoscale components await further research.

Though technologies currently 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. Thus 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. So far about $400 million has been invested in nanotechnology, with rather meager results.

Societal implications

There was an error working with the wiki: Code[7]

Potential risks of nanotechnology can broadly be grouped into three areas:

the risk to health and environment from nanoparticles and nanomaterials

the risk posed by molecular manufacturing (or advanced nanotechnology)

societal risks.

Nanoethics concerns the ethical and social issues associated with developments in nanotechnology, a science which encompass several fields of science and engineering, including biology, chemistry, computing, and materials science. Nanotechnology refers to the manipulation of very small-scale matter – a nanometer is one billionth of a meter, and nanotechnology is generally used to mean work on matter at 100 nanometers and smaller.

Social risks related to nanotechnology development include the possibility of military applications of nanotechnology (such as implants and other means for soldier enhancement) as well as enhanced surveillance capabilities through nano-sensors. However those applications still belong to science-fiction and will not be possible in the next decades. Significant environmental, health, and safety issues might arise with development in nanotechnology since

some negative effects of nanoparticles in our environment might be overlooked. Such issues include potential There was an error working with the wiki: Code[140] concerns for those involved in the manufacture of nanotechnologies. However nature itself creates all kinds of nanoobjects, so probable dangers are not due to the nanoscale alone, but due to the fact that toxic materials become more harmful when ingested or inhaled as nanoparticles (see There was an error working with the wiki: Code[141]).

The National Science Foundation (a major source of funding for nanotechnology 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 published study (with a foreword by Mihail Roco, head of the NNI) 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."

See also

There was an error working with the wiki: Code[142]

There was an error working with the wiki: Code[143]

There was an error working with the wiki: Code[144]

There was an error working with the wiki: Code[145]

There was an error working with the wiki: Code[146]

There was an error working with the wiki: Code[147]

There was an error working with the wiki: Code[148]

There was an error working with the wiki: Code[149]

Further reading

Geoffrey Hunt and Michael Mehta (2006), Nanotechnology: Risk, Ethics and Law. London: Earthscan Books.

Hari Singh Nalwa (2004), Encyclopedia of Nanoscience and Nanotechnology (10-Volume Set), American Scientific Publishers. ISBN 1-58883-001-2

Michael Rieth and Wolfram Schommers (2006), Handbook of Theoretical and Computational Nanotechnology (10-Volume Set), American Scientific Publishers. ISBN 1-58883-042-X

David M. Berube 2006. Nano-hype: The Truth Behind the Nanotechnology Buzz. Prometheus Books. ISBN 1-59102-351-3

There was an error working with the wiki: Code[8]

{{cite book|author=Akhlesh Lakhtakia (ed)|title=The Handbook of Nanotechnology. Nanometer Structures: Theory, Modeling, and Simulation|year=2004|

publisher=SPIE Press, Bellingham, WA, USA|id=ISBN 0-8194-5186-X}}

There was an error working with the wiki: Code[9]

{{cite book|author=Fei Wang & Akhlesh Lakhtakia (eds)|title=Selected Papers on Nanotechnology -- Theory & Modeling (Milestone Volume 182)|

publisher=SPIE Press, Bellingham, WA, USA|year=2006|id=ISBN 0-8194-6354-X}}

Roger Smith, Nanotechnology: A Brief Technology Analysis, CTOnet.org, 2004. http://www.ctonet.org/documents/Nanotech_analysis.pdf

Arius Tolstoshev, Nanotechnology: Assessing the Environmental Risks for Australia, Earth Policy Centre, September 2006. http://www.earthpolicy.org.au/nanotech.pdf

Hunt, G & Mehta, M (eds) Nanotechnology: Risk, Ethics & Law. Earthscan, London 2006.

External links

:For external links to companies and institutions involved in nanotechnology, please see There was an error working with the wiki: Code[150].

Commons has more media related to:

'<pesn type="link" url="http://commons.wikimedia.org/wiki/There was an error working with the wiki: Code[1]}" str="There was an error working with the wiki: Code[1]}"></pesn>'

Template: 4892

There was an error working with the wiki: Code[10]

Nanotechnology Now - News and information source on everything nano

Nanotechnology.com

Small Times - Nanotechnology News & Resources

Nanowerk Nanotechnology Portal

European Nanoforum

NanoEd Resource Portal - Repository of courses, concepts, simulations, professional development programs, seminars, etc.

National Center for Learning and Teaching in Nanoscale Science and Engineering (NCLT)

nanoHUB - Online Nanotechnology resource with simulation programs, seminars and lectures

NanoHive@Home - Distributed Computing Project

American Association for Cancer Research: Nanotechnology

Capitalizing on Nanotechnolgy's Enormous Promise - Article from CheResources.com

RARE Corporation Nanotechnology professional development short courses

There was an error working with the wiki: Code[46]

There was an error working with the wiki: Code[151]

Comments