Published on Nov 30, 2023
Nanotechnology is defined as fabrication of devices with atomic or molecular scale precision. Devices with minimum feature sizes less than 100 nanometers (nm) are considered to be products of nanotechnology. A nanometer is one billionth of a meter (10-9 m) and is the unit of length that is generally most appropriate for describing the size of single molecules.
The nanoscale marks the nebulous boundary between the classical and quantum mechanical worlds; thus, realization of nanotechnology promises to bring revolutionary capabilities. Fabrication of nanomachines, nanoelectronics and other nanodevices will undoubtedly solve an enormous amount of the problems faced by mankind today.
Nanotechnology is currently in a very infantile stage. However, we now have the ability to organize matter on the atomic scale and there are already numerous products available as a direct result of our rapidly increasing ability to fabricate and characterize feature sizes less than 100 nm. Mirrors that don't fog, biomimetic paint with a contact angle near 180°, gene chips and fat soluble vitamins in aqueous beverages are some of the first manifestations of nanotechnology. However, immenant breakthroughs in computer science and medicine will be where the real potential of nanotechnology will first be achieved.
Nanoscience is an interdisciplinary field that seeks to bring about mature nanotechnology. Focusing on the nanoscale intersection of fields such as physics, biology, engineering, chemistry, computer science and more, nanoscience is rapidly expanding. Nanotechnology centers are popping up around the world as more funding is provided and nanotechnology market share increases. The rapid progress is apparent by the increasing appearance of the prefix "nano" in scientific journals and the news. Thus, as we increase our ability to fabricate computer chips with smaller features and improve our ability to cure disease at the molecular level, nanotechnology is here.
The amount of space available to us for information storage (or other uses) is enormous. As first described in a lecture titled, 'There's Plenty of Room at the Bottom' in 1959 by Richard P. Feynman, there is nothing besides our clumsy size that keeps us from using this space. In his time, it was not possible for us to manipulate single atoms or molecules because they were far too small for our tools. Thus, his speech was completely theoretical and seemingly fantastic. He described how the laws of physics do not limit our ability to manipulate single atoms and molecules. Instead, it was our lack of the appropriate methods for doing so. However, he correctly predicted that the time would come in which atomically precise manipulation of matter would inevitably arrive.
Prof. Feynman described such atomic scale fabrication as a bottom-up approach, as opposed to the top-down approach that we are accustomed to. The current top-down method for manufacturing involves the construction of parts through methods such as cutting, carving and molding.
The power, flexibility, and ease of manufacture of conventional microelectronic two-state devices have been and continue to be at the heart of the revolution in computer and information technology that has swept the world during the past half century. Among the key properties of these solid state devices has been that they have themselves to miniaturization of electronic devices, especially computers.
First in the 1950’s and 1960’s solid state devices-transistors-replaced vacuum tubes and miniature all the devices (ex. Radios and televisions and electronic computers) that originally had been invented and manufactured using tube technology.
Then starting in mid 1960’s successive generations of smaller transistors began replacing larger ones. This permitted more transistors and more computing power to be packed in the same space.
In fact, as noted by Gordon Moore, the founder of Intel corporation, the no. of transistors of a solid state silicon integrated circuit “chip” begin doubling every 18 months. This trend now known as Moore’s law has continued to the present today. Very soon, how ever if computers are continue to get smaller and more powerful at the same rate, fundamentally new operational principles and the fabrication technologies, nanotechnology will need to be employed for miniature electronic devices. Still, it is important to understand how conventional electronics works in order to understand the challenges to further miniaturization and to learn how to over come them.
At the current rate of miniaturization, the conventional transistor technology will reach a minimum size limit at the turn of the century. Nonetheless, to maintain the current rate of advance in computers speed and information storage capacity, there must be continued increases in the density of computational elements on integrated circuit chips. This seems to be mandate and continued decreases drastically in size for transistor. So that, a change is necessary in the technology of the transistor.
Still, an electronic nanoComputer will continue to represent information in that storage and movement of electrons. Quantum dots and single-electron transistors govern tunneling of a small number of electrons through the influence of an electric field from a nearby gate electrode. Present-day, solid-state quantum dots can be made as small as 30 nanometers. In the future, they are likely to be made even smaller. Also, the quantum dot devices are sensitive to and can take advantage if the presence or absence of the charges of single electrons. Other electronic nanodevices tunneling devices (RTDs), also have been proposed, fabricated, and used in experiments. RTDs can be integrated with conventional microelectronics to create “hybrid” micro-nanoelectronic logic. These innovative devices have permitted the fabrication of much more dense electronic logic. Groups of quantum dots arranged to form “quantum-dot cells” and “wireless” cellular automata also are among the more innovative of the recent proposals.
A circular objective of nanotechnology is the ability to make products inexpensively. While the ability to make a few very small, very precise molecular machines very expensively would clearly be a major scientific achievement, it would not fundamentally change how we make most products.
Fortunately, we are surrounded and inspired by products that are marvelously complex and yet very inexpensive. By watching birds soar effortlessly through the air, so we can take inspiration from nature as we develop molecular manufacturing systems. Airplanes are very different from birds: a 747 bears only the smallest resemblance to a duck even though both fly. The artificial self replicating systems that have been envisioned for molecular manufacturing bear about the same degree of similarity to their biological counterparts as a car might bear to a horse.
Horses and cars both provide transportation. Horses, however, can get their energy from potatoes, corn, sugar, hay, straw, grass, and countless other types of “fuel”. A car uses only a single artificial and carefully refined source of energy: gasoline. Putting sugar or straw into its gas tank is not recommended. Cars, on the other hand, need roads on which to travel; have to be provided with odd and very unnatural parts; are often difficult to repair and in general are simply unable to cope with a complex environment. They work because we want them to work, and because we can fairly inexpensively provide carefully controlled conditions under which they can perform as we desire.
In the same way, the artificial self replicating systems that are being proposed for molecular manufacturing are inflexible and brittle. It’s difficult enough to design a system able to self replicate in a controlled environment. Let alone designing one that can approach the marvelous adaptability that hundreds of millions of years of evolution have give to living systems.
Designing a system that uses a single source of energy is both much easier to do and produces a much more efficient system: the horse pays for its ability to eat potatoes when grass isn’t available by being less efficient at both. For artificial systems where we wish to decrease design complexity and increase efficiency, we’ll design the system so that it can handle one source of energy, and handle that one source very well.
The mechanical designs proposed for nanotechnology are more reminiscent of a factory than of a living system. Molecular sale robotic arms able to move and position molecular parts would assemble rather rigid molecular products using methods more familiar to a machine shop than the complex brew of chemicals found in a cell. Although we are inspired by living systems, the actual designs are likely to owe more to design constraints and our human objectives than to living systems. Self-replication is but one of many abilities that living systems exhibit.
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