It is well known that many materials behave differently at extremely low temperatures, some materials becoming superconductors. One may wonder whether very, very small objects might also demonstrate interesting behavior. In 1959, Nobel Prize laureate Richard Feynman gave a talk entitled “There is Plenty of Room at the Bottom” that may be view as launching nanotechnology. In this prescient lecture he said “What I want to talk about is the problem of manipulating and controlling things on a small scale.” He describes a number of gedanken (“thought”) experiments. In particular he describes the process of reading and writing the entire 24 volumes of the Encyclopedia Britannica on the head of a pin. From there he goes on to imagine storing all the books in the world on a million pin heads. He then ponders about miniaturizing the computer. In the lecture he says that:
“Biology is not simply writing information; it is doing something about it. A biological system can be exceedingly small. Many of the cells are very tiny, but they are very active; they manufacture various substances; they walk around; they wiggle; and they do all kinds of marvelous things---all on a very small scale. Also, they store information. Consider the possibility that we too can make a thing very small which does what we want---that we can manufacture an object that maneuvers at that level!”
"The principles of physics, as far as I can see, do not speak against the possibility of maneuvering things atom by atom. It is not an attempt to violate any laws; it is something, in principle, that can be done; but in practice, it has not been done because we are too big"
K. Eric Drexler in his “Engines of Creation” published in 1086 proposed the "assembler", a device having a submicroscopic robotic arm under computer control. It will be capable of holding and positioning reactive compounds in order to control the precise location at which chemical reactions take place. This general approach should allow the construction of large atomically precise objects by a sequence of precisely controlled chemical reactions, building objects molecule by molecule. If designed to do so, assemblers will be able to build copies of themselves, that is, to replicate.
For the purpose of this article "nanotechnology" is a technology that involves all of the following:
1. Research and technology development at the atomic, molecular or macromolecular levels, in the length scale of approximately 1 - 100 nanometer range.
2. Creating and using structures, devices and systems that have novel properties and functions because of their small and/or intermediate size.
3. Ability to control or manipulate on the atomic scale.
Nanotechnology is an enabling technology that will have a significant impact on a broad array of application areas including electronics and computing, materials and manufacturing, energy, transportation, pharmaceuticals, health care, defense, biotechnology and so on. According to David Lewis, Director of Lucent's New Jersey Nanotech Consortium “It's is hard to think of an industry that won't be disrupted by nanotechnology.” NanoMarkets, a technology analyst firm, forecasts the market for nano-enabled electronics will reach $10.8 billion in 2007 and grow to $82.5 billion in 2011. The challenges facing nanotechnology include:
- Novel synthesis techniques
- Characterization of nanoscale properties
- Large scale production of materials
- Application development
Nanotubes as one example of nanotechnology
Fullerenes are one of only 3 types of naturally occurring forms of carbon (the other two being diamond and graphite). They are molecules composed entirely of carbon, taking the form of a hollow sphere, ellipsoid, or tube. Spherical fullerenes are sometimes called buckyballs, while cylindrical fullerenes are called buckytubes or nanotubes. The molecule was named for Richard Buckminster Fuller, a noted architect who popularized the geodesic dome. R.F. Curl, H.W. Kroto, and R.E. Smalley were awarded the 1996 Nobel Prize in Chemistry for his discovery and characterization of buckminsterfullerenes.
The most common fullerenes is C60 whose structure of is that of a truncated icosahedron, which resembles a round soccerball of the type made of hexagons and pentagons, with a carbon atom at the corners of each hexagon and a bond along each edge. A polymerized single-walled nanotubule ( P-SWNT) is a substance composed of polymerized fullerenes in which carbon atoms from one buckytube bond with carbons in other buckytubes. In the field of nanotechnology, heat resistance and Superconductivity are some of the more heavily studied properties.
Experimentalists and theorists have shown or suggested that solids based on buckyballs can be insulators, conductors, semiconductors, or even superconductors when doped with other atoms or molecules. Pure buckyball solids form crystal structures, like graphite or diamond, that are insulators or semiconductors. However, when doped with an alkali metal, such as potassium or rubidium, these solids can become electricity-conducting metals. Buckyballs doped with an organic reducing agent exhibit ferromagnetic properties.
In 1991 Sumio Iijima, an NEC researcher, discovered a related molecular shape known as the "carbon nanotube" (CNT). CNT is a tubular form of carbon with diameter as small as 1 nm and with a length of a few nm to microns. CNT is configurationally equivalent to a two dimensional grapheme sheet rolled into a tube. These nanotubes have unusual heat and electrical conductivity characteristics. They are about 100 times stronger than steel but just a sixth of the weight. Their conductivity is six orders of magnitude higher than copper and they have very high current carrying capacity. CNTs can be metallic or semiconducting, depending on chirality. Their electronic properties can be tailored through application of external magnetic field, application of mechanical deformation and so forth.
Different types of carbon nanotubes can be produced in various ways. The most common techniques used nowadays are: arc discharge, laser ablation, chemical vapour deposition and flame synthesis. Purification of the tubes can be divided into a couple of main techniques: oxidation, acid treatment, annealing, sonication, filtering and functionalisation techniques. Possible applications for nanotubes exist in the fields of energy storage, molecular electronics, nanomechanic devices, and composite materials. The four types of energy storage known in carbon nanotubes are: electrochemical hydrogen storage, gas phase intercalation, electrochemical lithium storage and charge storage in supercapacitors.
The National Nanotechnology Initiative (NNI) is a federal R&D program established to coordinate the multiagency efforts in nanoscale science, engineering, and technology. The goals of the NNI are to:
- Maintain a world-class research and development program aimed at realizing the full potential of nanotechnology;
- Facilitate transfer of new technologies into products for economic growth, jobs, and other public benefit;
- Develop educational resources, a skilled workforce, and the supporting infrastructure and tools to advance nanotechnology; and,
- Support responsible development of nanotechnology.
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-- Jack Horgan, EDACafe.com Contributing Editor.