An official website of the United States government. Nanotechnology is the understanding and control of matter at the nanoscale, at dimensions between approximately 1 and nanometers, where unique phenomena enable novel applications. Encompassing nanoscale science, engineering, and technology, nanotechnology involves imaging, measuring, modeling, and manipulating matter at this length scale.
Matter such as gases, liquids, and solids can exhibit unusual physical, chemical, and biological properties at the nanoscale, differing in important ways from the properties of bulk materials and single atoms or molecules.
Some nanostructured materials are stronger or have different magnetic properties compared to other forms or sizes of the same material. Others are better at conducting heat or electricity. The ability to visualize and manipulate matter at the nanoscale has led to a diverse technology that ranges from better and faster electronics and more efficient fuel usage to sensing, drug discovery and stronger, more resistant materials.
It has the prospect of affecting the lives of all of us and already a number of applications are in the market-place. But in our development of these technologies, we need to take care to reduce the risks of the adverse consequences that usually attend new applications of science. What is nanotechnology? This is not as easy to answer as one might think because the term encompasses a huge range of activities.
Nanotechnology has received enormous attention in the last 15 years—some commentators and financial observers—such as the finance house Merryl Lynch [ 1 ]—have even gone so far as to suggest that the impact of nanotechnology will be so great that the term will be used to describe a new era of world economic growth. However, nano has also long been used as a prefix in scientific circles to mean 1 billionth using billion in its American sense of a one followed by nine zeros.
On that score, we might expect nanotechnology to have something to do with technologies that are working at the nanometre level, and this is the general sense in which the term is used today. Nanoscience is the study of phenomena and manipulation of materials at atomic, molecular and macromolecular scales, where properties differ significantly from those at larger scale. Nanotechnologies are the design, characterization, production and application of structures, devices and systems by controlling shape and size at nanometre scale.
Nanoscience, arguably, has been around since the early part of the 20th century, but the idea that there might be some technological advantages to be gained by working at the very small scale came much later. In this lecture—which actually had almost no physics in it but is mainly concerned with the technology of making things—he explored the benefits that might accrue to us if we started manufacturing things on the very small scale.
The ideas he put forward were remarkably prescient. For example, he foresaw the techniques that could be used to make large-scale integrated circuits and the revolutionary effects that the use of these circuits would have upon computing.
He talked about making machines for sequencing genes by reading DNA molecules. He foresaw the use of electron microscopes for writing massive amounts of information in very small areas.
He also talked about using mechanical machines to make other machines with increasing precision. Many of his predictions in that lecture have come true, and are all aspects of what we would now call nanotechnology, although he did not use the term itself.
The first use of the term nanotechnology was by Norio Taniguchi who, in , gave a talk describing how the dimensional accuracy with which we make things had improved over time [ 4 , 5 ]. He studied the developments in machining techniques over the period from until the early s and predicted correctly that by the late s techniques would have evolved to a degree that dimensional accuracies of better than nm would be achievable.
He applied the term nanotechnology to this. All the early running in the field of nanotechnology was made by physicists and engineers, who mainly thought in terms of using one machine, made from components manufactured to a certain level of precision, to make objects, or components for another machine, to a greater precision.
We all use advanced microprocessors in our portable computers. Hence, the critical dimensions on a chip will be down to 45 nm by late and to 22 nm by the end of the decade. The technologies established by the semiconductor industry are also now being applied to the manufacture of tiny micromechanical machines for sensing and actuation. We can start to see here the enormous effects that working at the very small scale is having on our world.
Feynman put forward two other themes in his lecture. First, he had envisaged the possibility of making machines that could pick up and place single atoms to make chemical compounds.
They won the Nobel Prize for this work in Eigler and his group have done some remarkable work, mainly using the technique to explore basic physical and quantum mechanical phenomena [ 6 ]. Gimzewski at IBM has used similar techniques, but at room temperature, to push single molecules around on surfaces. Feynman's second vision in was of a factory in which billions of very small machine tools were drilling and stamping myriad tiny mechanical parts, which would then be assembled into larger products.
All it would need was a supply of raw materials and a source of energy. Those replicas would make more replicas, and the result would be an exponential growth in the number of the machines—until either the source of raw materials or the energy was exhausted.
The clanking replicator concept is reduced to very small size through the use of mechanical components that are made on the molecular scale. The exponential growth would lead to billions of assemblers that would be programmed to work in concert with each other to build virtually anything required.
Clearly, such a technology would have enormous economic implications, in terms of material and energy use, effects on employment, etc. Actually, there is now a new variant on this vision, which postulates the fusion of nanotechnology with biotechnology to create an assembler that is at least partly biologically based. The potential feasibility of these ideas will be discussed in more detail below.
Some remarkable developments in materials science and chemistry have occurred over the last 15 years or so, particularly where small size plays a big role in determining basic properties. In this field, size matters! For example, the colours of light absorption and emission change. Very small particles nanoparticles of materials like cadmium telluride are being used in applications such as the labelling of biological molecules and in new types of displays.
These can be made with amazing precision in size—within a couple of nanometres—using reasonably standard wet chemical processes. Very small particles less than a few hundred nanometres in size do not scatter visible light. Good absorbers of ultraviolet UV light such as titanium dioxide are now being made in nanoparticulate form for sunscreens. The fact that the particles are so small means that they are invisible on the skin, while still being highly effective as UV blockers.
Very small particles also possess high surface areas per unit of mass. Oxonica, a start-up company from Oxford University, has found that nanoparticles of cerium oxide when introduced into diesel fuel act as oxidation catalysts during combustion. If we look at other areas of materials science, we see that new forms of carbon have been discovered.
Harry Kroto from the University of Sussex, together with Richard Smalley and Robert Curl, discovered the carbon molecule in and won the Nobel Prize for chemistry in This molecule is a sphere 0. It is amusing to note that if you could blow up the carbon molecule to the size of a soccer ball, the soccer ball, if blown up by the same factor, would be about half the size of the planet Jupiter!
In , Iijima discovered carbon nanotubes. These are like sheets of graphite rolled into long tubes, each one being terminated with a fullerene group. They also have remarkable properties. They can be either metallic or semiconducting, depending on the precise way in which the carbon atoms are assembled in the tube.
The metallic forms have electrical conductivities times that of copper and are now being mixed with polymers to make conducting composite materials for applications such as electromagnetic shielding in mobile phones and static electricity reduction in cars. They possess mechanical properties that are many times those of steel, bringing the promise of replacing carbon fibres in a new generation of high-strength composite materials. They have been demonstrated in applications as diverse as super-capacitors for energy storage, field emission devices for flat-panel displays and nanometre-sized transistors.
Clearly, these nanomaterials hold huge promise for the future. So, what is nanotechnology? Firstly, it is very diverse. It employs all the conventional scientific and engineering subjects in order to achieve new applications through the exploitation of phenomena in which small size is the key to obtaining an exploitable property.
Secondly, it is an area of endeavour where there are real and remarkable properties that we can seek to exploit. Thirdly, and increasingly, we are starting to see synthesis between different areas of nanotechnology. In order to understand the unusual world of nanotechnology, we need to get an idea of the units of measure involved.
A centimeter is one-hundredth of a meter, a millimeter is one-thousandth of a meter, and a micrometer is one-millionth of a meter, but all of these are still huge compared to the nanoscale.
A nanometer nm is one-billionth of a meter, smaller than the wavelength of visible light and a hundred-thousandth the width of a human hair [source: Berkeley Lab ].
As small as a nanometer is, it's still large compared to the atomic scale. An atom has a diameter of about 0. An atom's nucleus is much smaller -- about 0.
Atoms are the building blocks for all matter in our universe. You and everything around you are made of atoms. Nature has perfected the science of manufacturing matter molecularly.
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