A mite next to a gear chain produced using nanotechnology Nanotechnology as a collective term refers to technological developments on the nanometer scale, usually 0.1-100nm. (One nanometer equals one thousandth of a micrometer or one millionth of a millimeter.) The term sometimes applies to any microscopic technology.
Due to the small size at which nanotechnology operates, physical phenomena not observed at the macroscopic scale dominate. These nanoscale phenomena include quantum size effects and short range forces such as van der Waals forces. Furthermore the vastly increased ratio of surface area to volume promotes surface phenomena.
Since the complexity (i.e., number of features per unit of area) of computers is growing exponentially it is believed that it will develop into nanotechnology, i.e., molecular electronics, in the near future if Moore's law is to be upheld.
The term nanotechnology is often used interchangeably with molecular nanotechnology (also known as "MNT"), a hypothetical advanced form of nanotechnology that is believed will be developed some time in the future.
History
The first mention of nanotechnology (not yet using that name) occurred in a talk given by Richard Feynman in 1959, entitled There's Plenty of Room at the Bottom. Feynman suggested a means to develop the ability to manipulate atoms and molecules "directly", by developing a set of one-tenth-scale machine tools analogous to those found in any machine shop. These small tools would then help to develop and operate a next generation of one-hundredth-scale machine tools, and so forth. As the sizes get smaller, we would have to redesign some tools because the relative strength of various forces would change. Gravity would become less important, surface tension would become more important, van der Waals attraction would become important, etc. Feynman mentioned these scaling issues during his talk. Nobody has yet effectively refuted the feasibility of his proposal.
The term 'Nanotechnology' was created by Tokyo Science University professor Norio Taniguchi in 1974 to describe the precision manufacture of materials with nanometer tolerances. In the 1980s the term was reinvented and its definition expanded by K Eric Drexler, particularly in his 1986 book Engines of Creation: The Coming Era of Nanotechnology. He explored this subject in much greater technical depth in his MIT doctoral dissertation, later expanded into Nanosystems: Molecular Machinery, Manufacturing, and Computation [1] (http://www.zyvex.com/nanotech/nanosystems.html). Computational methods play a key role in the field today because nanotechnologists can use them to design and simulate a wide range of molecular systems.
Early discussions of nanotechnology involved the notion of a general-purpose assembler with a broad range of capability to build different molecular structures. The possibility of self-replication, the idea that assemblers could build more assemblers, suggests that nanotechnology could reduce the price of many physical goods by several orders of magnitude. Self-replication is also the basis for the grey goo scenario. More recent thinking has focused instead on a more factory-oriented approach (http://www.zyvex.com/nanotech/convergent.html) to construction. The smallest elements of a product would be built on assembly lines, then assembled into progressively larger assemblies until the final product is complete.
A cut-away view of a desktop nanofactory: http://www.foresight.org/Images/DesktopFactory400x386.jpg
New materials, devices, technologies Nanotechnology develops minute technology; this is a model of "nanogears", only a few atoms wide. As our science becomes more sophisticated it naturally enters the realm of what is arbitrarily labelled nanotechnology. The essence of nanotechnology is that as we scale things down they start to take on extremely novel properties. Nanoparticles (blobs at nanometre scale), for example, have very interesting properties and are proving extremely useful as catalysts and in other uses. If we ever do make nanobots, they will not be scaled down versions of contemporary robots. It is the same scaling effects that make nanodevices so special that prevent this. Nanoscaled devices will bear much stronger resemblance to nature's nanodevices: proteins, DNA, membranes etc. Supramolecular assemblies are a good example of this.
One fundamental characteristic of nanotechnology is that nanodevices self-assemble. That is, they build themselves from the bottom up. 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 guiding 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, and for these reasons it is quite simply not feasible to construct nanoscaled devices atom by atom. You don't want to assemble a billion transistors into a microchip by taking an hour to place each transistor, but these techniques can be used for things like such as helping guide self-assemling systems.
One of the problems facing nanotechnology is how to assemble atoms and molecules into smart materials and working devices. Supramolecular chemistry is here a very important tool. Supramolecular chemistry is the chemistry beyond the molecule, and molecules are being designed to self-assemble into larger structures. In this case, biology is a place to find inspiration: cells and their pieces are made from self-assembling biopolymers such as proteins and protein complexes. One of the things being explored is synthesis of organic molecules by adding them to the ends of complementary DNA strands such as ----A and ----B, with molecules A and B attached to the end; when these are put together, the complementary DNA strands hydrogen bonds into a double helix, ====AB, and the DNA molecule can be removed to isolate the product AB.
Natural or man-made particles or artifacts often have qualities and capabilities quite different from their macroscopic counterparts. Gold, for example, which is chemically inert at normal scales, can serve as a potent chemical catalyst at nanoscales.
"Nanosize" powder particles (a few nanometers in diameter, also called nano-particles) are potentially important in ceramics, powder metallurgy, the achievement of uniform nanoporosity, and similar applications. The strong tendency of small particles to form clumps ("agglomerates") is a serious technological problem that impedes such applications. However, a few dispersants such as ammonium citrate (aqueous) and imidazoline or oleyl alcohol (nonaqueous) are promising additives for deagglomeration. (Those materials are discussed in "Organic Additives And Ceramic Processing," by D. J. Shanefield, Kluwer Academic Publ., Boston.)
In October 2004, researchers at The University Of Manchester suceeded in forming a small piece of material only 1 atom thick called graphene.[2] (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15499015) Robert Freitas has suggested that graphene might be used as a deposition surface for a diamandoid mechanosynthesis tool.[3] (http://www.molecularassembler.com/Papers/PathDiamMolMfg.htm)
Potential risks An often cited worst-case scenario is the so-called "grey goo", a substance into which the surface objects of the earth might be transformed by amok-running, self-replicating nano-robots, a process which has been termed global ecophagy. Defenders point out that smaller objects are more susceptible to damage from radiation and heat (due to greater surface area-to-volume ratios): nanomachines would quickly fail when exposed to harsh climates. More realistic are criticisms that point to the potential toxicity of new classes of nanosubstances that could adversely affect the stability of cell walls or disturb the immune system when inhaled or digested [4] (http://www.nanomedicine.com/NMIIA.htm). Objective risk assessment can profit from the bulk of experience with long-known microscopic materials like carbon soot or asbestos fibres.
Nanotechnology in fiction Nanotechnology has also become a prominent theme in science fiction [5] (http://www.geocities.com/asnapier/nano/n-sf/), for example with the Borg and also the race of Nanites in Star Trek, the Replicators in Stargate SG-1, the T-X (Terminatrix) in Terminator 3: Rise of the Machines, Manga such as GUNNM the games Deus Ex, Neocron, Anarchy Online, Metal Gear Solid, and the Ratchet & Clank series, the books Alexandr Lazarevich' The NanoTech Network [6] (http://www.webcenter.ru/~lazarevicha/ntn_toc.htm), Greg Bear's Blood Music and Slant, Michael Crichton's Prey, Neal Stephenson's The Diamond Age and Snow Crash, and Alastair Reynolds' Revelation Space, Chasm City, Redemption Ark and Absolution Gap.
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External links - Nanotec Congress in Brazil (http://www.nanotec2005.com/)
- Foresight Institute (http://www.foresight.org/)
- The London Centre for Nanotechnology (http://www.london-nano.ucl.ac.uk/lcn/index2.htm)
- the Nanoscale Physics Research Laboratory, Birmingham, England (http://nprl.bham.ac.uk/)
- Wise-Nano (http://www.wise-nano.org) A Wiki project, initiated by the Center for Responsible Nanotechnology (http://crnano.org/) and devoted to Molecular Manufacturing
- PNAS supplement: Nanoscience: Underlying Physical Concepts and Phenomena (http://www.pnas.org/content/vol99/suppl_2/)
- Molecular Assembler website (http://www.MolecularAssembler.com)
- Nanotechnology news and related research (http://nanotechwire.com/)
- Nanotechnology news links - updated daily (http://www.NTalert.com/)
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