NANOTECHNOLOGY
Nanotechnology is defined as the science and technology of building electronic circuits and devices from single atoms and molecules, or the branch of engineering that deals with things smaller than 100 nanometers. A nanometer is about ten thousand times smaller than the width of a human hair. Nanotechnology deals with and manipulates anything that occurs within the scale of a nanometer.
Nanotechnology is an extension of the field of materials science. Materials science departments at colleges and universities around the world are leading the way in current nanotechnology breakthroughs. The term Nanotechnology is also often used to describe the interdisciplinary fields of science devoted to the study of the nanoscale phenomena utilized in Nanotechnology.
The future benefits that nanotechnology research could serve include advances in telecommunications, information technology, healthcare and pharmaceuticals.
A Vision
In his famous speech There's Plenty of Room at the Bottom in 1959, Richard Feynman discussed the possibility of manipulating and controlling things on a molecular scale in order to achieve electronic and mechanical systems with atomic sized components. He concluded that the development of technologies to construct such small systems would be interdisciplinary, combining fields such as physics, chemistry and biology, and would offer a new world of possibilities that could radically change the technology around us.
Miniaturization
A few years later, in 1965, Moore noted that the number of transistors on a chip had roughly doubled every other year since 1959, and predicted that the trend was likely to hold as each new generation of microsystems would help to develop the next generation at lower prices and with smaller components.
To date, the semiconductor industry has been able to fulfill Moore's Law, in part through the reduction of lateral feature sizes on silicon chips from around 10 micrometers in 1965 to 45-65 nm in 2007 via changing from the use of optical contact lithography to deep ultraviolet projection lithography.
In 1974 in Japan, Norio Taniguchi coined the word "nano-technology" to describe semiconductor processes such as thin film deposition and ion beam milling exhibiting characteristic control on the order of a nanometer: "Nano-technologyz mainly consists of the processing of separation, consolidation, and deformation of materials by one atom or one molecule."
Since Feynman's 1959 speech the arts of "seeing" and "manipulation" at the nanoscale have progressed from transmission electron microscopy (TEM) and scanning electron microscopy (SEM) to various forms of scanning probe microscopy including scanning tunneling microscopy (STM) developed by Binnig and Rohrer at IBM Zurich and atomic force microscopy (AFM) devloped by (Binnig and Quate?) The STM, in particular, is capable of single-atom manipulation on conducting surfaces and has been used to build "quantum corrals" of atoms in which quantum mechanical wave function phenomena can be discerned. These atomic-scale manipulation capabilities prompt thoughts of building up complex atomic structures via manipulation rather than traditional stochastic chemistry.
The American engineer Eric Drexler has speculated extensively about the laboratory synthesis of machines at the molecular level via manipulation techniques, emulating biochemistry and producing components much smaller than any microprocessor via techniques which have been called molecular nanotechnology or MNT.
Successful realization of the MNT dream would comprise a collection of technologies which are not currently practical, and the dream has resulted in considerable hyperbolic description of the resulting capabilities. While realization of these capabilities would be a vindication of the hype associated with MNT, concrete plans for anything other than computer modeling of finished structures are scant. Somehow, a means has to be found for MNT design evolution at the nanoscale which mimics the process of biological evolution at the molecular scale. Biological evolution proceeds by random variation in ensemble averages of organisms combined with culling of the less-successful variants and reproduction of the more-successful variants, and macroscale engineering design also proceeds by a process of design evolution from simplicity to complexity as set forth somewhat satirically by John Gall:
"A complex system that works is invariably found to have evolved from a simple system that worked. . . . A complex system designed from scratch never works and can not be patched up to make it work. You have to start over, beginning with a system that works."
A breakthrough in MNT is needed which proceeds from the simple atomic ensembles which can be built with, e.g., an STM to complex MNT systems via a process of design evolution. A handicap in this process is the difficulty of seeing and manipulation at the nanoscale compared to the macroscale which makes deterministic selection of succesful trials difficult; in contrast biological evolution proceeds via action of what Richard Dawkins has called the "blind watchmaker" comprising random molecular variation and deterministic survival/death.
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A perspective on Nanotechnology
The impact on society and our lives of the continuous downscaling of systems is profound, and continues to open up new frontiers and possibilities.
However, no exponential growth can continue forever, and the semiconductor industry will eventually reach the atomic limit for downsizing the transistor. Atoms in solid matter are typically one or two hundred picometers apart so nanotechnology involves manipulating individual structures which are between ten and ten thousand atoms across; for example, the gate length of a 45 nm transistor is about 180 silicon atoms long. Such very small structures are vulnerable to molecular level damage by cosmic rays, thermal activity, and so forth. The way in which they are assembled, designed and used is different from prior microelectronics.
New ways
Today, as that limit still seems to be some 20 years in the future, the growth is beginning to take new directions, indicating that the atomic limit might not be the limiting factor for technological development in the future, because systems are becoming more diverse and because new effects appear when the systems become so small that quantum effects dominate. The semiconductor devices show an increased diversification, dividing for instance processors into very different systems such as those for cheap disposable chips, low power consumption portable devices, or high processing power devices. Microfabrication is also merging with other branches of science to include for instance chemical and optical micro systems. In addition, microbiology and biochemistry are becoming important for applications of all the developing methods. This diversity seems to be increasing on all levels in technology and many of these cross-disciplinary developments are linked to nanotechnology.
Diversification
As the components become so small that quantum effects become important, the diversity will probably further increase as completely new devices and possibilities begin to open up that are not possible with the bulk materials of today's technology.
The Nanorevolution?
The visions of Feynman are today shared by many others: when nanotechnology is seen as a general cross disciplinary technology, it has the potential to create a coming "industrial" revolution that will have a major impact on society and everyday life, comparable to or exceeding the impact of electricity and information technology.
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The Future of Technology
The future of technology is in some ways easy to predict. Computers will become faster, materials will become stronger, and medicine will cure more diseases. Nanotechnology, which works on the nanometer scale of molecules and atoms, will be a large part of this future, enabling great improvements in all these technologies. Advanced nanotechnology will work with molecular precision, building a wide range of products that are impossible to make today.
Why focus on productive nanosystems and the large-scale molecular manufacturing processes that they will enable? Because these developments will extend the range of what human beings can manufacture, and through this will change the foundations of physical technology.
Every manufacturing method is a method for arranging atoms. Most methods arrange atoms crudely: even the finest commercial microchips are grossly irregular at the atomic scale, and much of today's nanotechnology faces the same limit. Chemistry and biology, by contrast, make molecules defined by particular arrangements of atoms -- always with the same numbers, kinds, and linkages. Chemists use clever methods to do this, but these methods don’t scale up well. Biology, however, uses a different, more scalable method: cells contain productive nanosystems (ribosomes) that use digital data (from genes) to guide the assembly of molecular objects (proteins) that they serve as parts of molecular machines. Molecular manufacturing will likewise use stored data to guide construction work done by molecular machines, greatly extending abilities in nanotechnology.
The Molecular-Assembler Concept
The basic idea of controlled molecular assembly is simple: where chemists mix molecules in solution, allowing them to wander and bump together at random, molecular assemblers will instead position molecules, bringing them together in a specific position, orientation, and sequence. Letting molecules bump at random leads to unwanted reactions -- a problem that grows worse as products get larger. By holding and positioning molecules, assemblers will control how the molecules react, building complex structures with atomically precise control.
Picture an industrial robot arm standing next to an unfinished workpiece. A conveyor belt supplies the arm with parts, each mounted on a handle. Step after step, the belt advances, the robot grips a fresh handle, plugs the attached part into the workpiece, then puts the empty handle back on the belt. Eventually, the workpiece is finished and another belt moves it away, shifting a new unfinished workpiece into place.
To picture a molecular assembler in a manufacturing system, imagine that all the parts are measured in nanometers, and that the transferred parts are just a few atoms, shifting from handle to workpiece through a chemical reaction at a specific site. An assembler will work as part of a larger system that prepares tools, puts them on the conveyor, and controls the programmable positioning mechanism. Their small moving parts will enable them to operate at high frequencies: because each motion traverses less than a millionth of a meter, each can be completed in less than a millionth of a second. This enables extremely high productivity.
Machines of this sort will be complex systems that are several technology generations away. Indeed, no one is even trying to directly build molecular assemblers today, because nanotechnology is still in its infancy. We can see a path to assemblers, just as the rocketry pioneers of the 1930s and 1940s could see a path to the Moon. But like those pioneers, we aren't ready to attempt the final goal. They knew they must first launch many satellites, just as we must first build many molecular machines. Some of the early machines may resemble the small, simple productive nanosystems that are used today in nature and in biotechnology.
Understanding Advanced Capabilities
We can catch a glimpse of future technologies because we sometimes can understand things that we can't yet build. Chemistry, biology, engineering and applied physics all provide useful perspectives.
Chemistry shows how structures can form when reactive molecules meet. By using molecular machinery to guide reactive molecules, similar structures can be built at larger scales. The products can be stronger, tougher and more capable than the delicate structures found in living cells.
Biology shows that molecular machines can exist, can be programmed with genetic data, and can build more molecular machines. Biology shows that the products of molecular machine systems can be as low-cost as potatoes. Molecular manufacturing will make a far wider range of products for similarly low costs.
Engineering shows that precisely made parts can be combined to make computers, motors, factories, and a host of useful gadgets. Applied physics, aided by computer modeling, shows that these sorts of devices can be built from atomically precise parts of nanometer scale. These glimpses of future technologies are enough to show some of the potential for molecular manufacturing.
Directions and Applications
Molecular manufacturing will bring both great opportunities and great potential for abuse. Advanced systems could be used to build large, complex products cleanly, efficiently, and at low cost. Building with atomic precision, desktop-scale (and larger) manufacturing systems could produce the products like the following, with consequences for many global problems:
1. Inexpensive, efficient solar energy systems, a renewable, zero-carbon emission source.
2. Desktop computers with a billion processors.
3. Medical devices able to destroy viruses and cancer cells without damaging healthy cells.
4. Materials 100 times stronger than steel.
5. Superior military systems.
6. More molecular manufacturing systems.
Faster, cheaper, cleaner production of superior products will also be disruptive. Costs, resource requirements and economic organization will be transformed. Advanced lethal and non-lethal weapons, deployed quickly and cheaply, could make the world a more dangerous place. The list of potential consequences is long, and as with all powerful technologies, the results will depend on the intent of the users.
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Outlook
In laboratories around the world, researchers are developing useful products and providing instruments, techniques and nanoscale components that will enable the development of future productive nanosystems.
We have seen steady advances in understanding and controlling atoms, molecules and atomically precise structures. Some instruments now enable researchers to observe and move individual atoms and molecules. The most widely known of these is the scanning tunneling microscope (STM), first developed by researchers at IBM Zurich's labs.
We have also seen progress in building novel structures along the lines proposed in my 1981 paper in the Proceedings of the National Academy of Sciences. This is the field of protein engineering which, together with DNA engineering, has demonstrated design and synthesis of atomically precise molecular objects like those that function as components of the molecular machinery, processing and electronics in biology.
Another area of rapid progress is computational modeling. Advances in hardware and software enable design and simulation-based testing of molecular devices, giving results with greater accuracy for structures on larger scales. This progress is crucial to the development of molecular systems engineering.
In considering these goals and accomplishments, it is important to distinguish long-term promise from present-day capabilities. Developing advanced productive nanosystems will require a multi-stage process in which today's laboratory capabilities are used to build molecular tools with broader capabilities. These tools, in turn, will be used in the next stage of development. Nanotechnology using productive nanosystems and their products will build on and extend the nanotechnologies of today, enabling a progressively broader range of applications.
The research that will support these developments is underway in laboratories in every industrial country. Unlike past revolutions in technology, the U.S., Europe and Asia are all making similar progress.
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