Applications of Nanotechnology- A general view
By- Dr.Ratnam Challa
Physicists all over the world are concentrating on application oriented Physics rather than Fundamental Physics. The Physics of the Nanoworld is the latest field of active research in this century. The last few years has seen a gold rush to claim patents at the nanoscale. Over 800 nano-related patents were granted in 2003, and the numbers are increasing year to year. Corporations are already taking out broad-ranging patents on nanoscale discoveries and inventions. Corporations like NEC and IBM, hold the basic patents on carbon nanotubes, one of the current cornerstones of Nanotechnology. Carbon NanoTubes (CNT) have a wide range of uses, and look set to become crucial to several industries from electronics and computers, to strengthened materials to drug delivery and diagnostics. Hewlett-Packard has proposed the use of a Nanomaterial called “Memristor” as a future replacement of Flash memory.
What is Nanotechnology?
Nanotechnology, shortened to “nanotech“, is the study of controlling of matter on an atomic and molecular scale. Generally nanotechnology deals with structures sized between 1 to 100 nanometer in at least one dimension, and involves developing materials or devices within that size. One nanometer (nm) is one billionth, or 10−9 of a meter. By comparison, typical Carbon-Carbon Bond-Lengths, or the spacing between these atoms in a molecule, are in the range 0.12–0.15 nm, and a DNA double-helix has a diameter around 2 nm. On the other hand, the smallest cellular life-forms, the bacteria of the genus Mycoplasma are around 200 nm in length.
A number of physical phenomena become pronounced as the size of the system decreases. The electronic properties of solids are altered with great reductions in particle size. Quantum mechanical effects and Statistical mechanical effects become dominant when the nanometer size range is reached. A number of physical (mechanical, electrical, optical, etc.) properties change at such dimensions when compared to macroscopic systems. One example is the increase in surface area to volume ratio altering mechanical, thermal and catalytic properties of materials. Diffusion reactions at nanoscale, nanostructure materials and nanodevices with fast ion transport are generally referred to Nanoionics.
Mechanical properties of Nanosystems are of interest in the Nanomechanics research. Materials reduced to the nanoscale can show different properties compared to what they exhibit on a macro scale, enabling unique applications. For instance
1) Opaque substances become transparent (copper);
2) Stable materials turn combustible (aluminum);
3) Insoluble materials become soluble (gold).
4) A material such as gold, which is chemically inert at normal scales, can serve as a potent chemical catalyst at nano scales.
Much of the fascination with nanotechnology stems from these quantum and surface phenomena that matter exhibits at the nanoscale.
Nanotechnology and Nanoscience got a boost in the early 1980s with two major developments: the birth of Cluster Science and the invention of the Scanning Tunnelling Microscope (STM). This development led to the discovery of “Fullerenes” in 1985 and the structural assignment of “Carbon Nanotubes” a few years later. In another development, the synthesis and properties of semiconductor Nanocrystals were studied. This led to a fast increasing number of Semiconductor nanoparticles and Quantum dots. Quantum dots are nanoscale objects, which can be used, among many other things, for the construction of lasers. The advantage of a Quantum dot laser over the traditional semiconductor laser is that their emitted wavelength depends on the diameter of the dot. Quantum dot lasers are cheaper and offer a higher beam quality than conventional laser diodes.
APPLICATIONS OF NANOTECHNOLOGY
Nanomedicine is the application of Nanotechnology in Medicine. The approaches to Nanomedicine range from the medical use of Nanomaterials to Nanoelectronic biosensors, and even possible future applications of Molecular Nanotechnology. Nanomedicine predicts to deliver a valuable set of research tools and clinically helpful devices in the near future. The National Nanotechnology Initiative (NIN) expects new commercial applications in the pharmaceutical industry that may include advanced drug delivery systems, new therapies, and In-Vivo imaging. Neuro-electronic interfaces and other Nanoelectronic-based sensors are another active goal of research. Further down the line, the speculative field of Molecular Nanotechnology believes that cell repair machines could revolutionize medicine and the medical field.
Nanotechnology has been used in the medical field in delivering drugs to specific cells using nanoparticles. The overall drug consumption and side-effects can be lowered significantly by depositing the active agent in the morbid region only and in no higher dose than needed. This highly selective approach reduces costs and human suffering. Use of Dendrimers (Dendrimers are repeatedly branched, roughly spherical large molecules) and nanoparticles in Targeted and controlled drug delivery, is an emerging field of research called Nanobiopharmacuetics. The basic point to use drug delivery is based upon three facts: a) efficient encapsulation of the drugs, b) successful delivery of said drugs to the targeted region of the body, and c) successful release of that drug there.
NEMS (Nano Electro-Mechanical Systems) are being investigated for the active release of drugs in patients. Some potentially important applications include cancer treatment with iron nanoparticles or gold shells. A targeted or personalized medicine reduces the drug consumption and treatment expenses resulting in an overall social benefit by reducing the costs to the public health system. Nanotechnology is also opening up new opportunities in implantable delivery systems, which are often preferable to the use of injectable drugs, because the latter frequently display first-order kinetics (the blood concentration goes up rapidly, but drops exponentially over time). This rapid rise may cause difficulties with toxicity, and drug efficacy can diminish as the drug concentration falls below the targeted range.
In 1965, Gordon Moore, one of the founders of Intel Corporation, made the outstanding prediction that the number of transistors that could be fit in a given area would double every 18 months for the next ten years. This it did and the phenomenon became known as “Moore’s Law” This trend has continued far past the predicted 10 years until this day, going from just over 2000 transistors in the original 4004 processors of 1971 to over 700,000,000 transistors in the Core2 Processor. There has, of course, been a corresponding decrease in the size of individual electronic elements, going from millimeters in the 60’s to hundreds of nanometers in modern circuitry of this millennium. In 1999, the ultimate CMOS transistor developed at the Laboratory for Electronics and Information Technology in Grenoble, France, tested the limits of the principles of the MOSFET transistor with a diameter of 18 nm (approximately 70 atoms placed side by side). This was almost one tenth the size of the smallest industrial transistor in 2003 (130 nm in 2003, 90 nm in 2004, 65 nm in 2005 and 45 nm in 2007). It enabled the theoretical integration of seven billion junctions on a €1 coin. However, the CMOS transistor, which was created in 1999, was not a simple research experiment to study how CMOS technology functions, but rather a demonstration of how this technology functions on a molecular scale. Manufacturers like NANTERO have developed a Carbon Nano Tube (CNT) based crossbar memory called Nano-RAM. Carbon nanotubes are electrically conductive and due to their small diameter of several nanometers, they can be used as field emitters with extremely high efficiency for field emission display (FED). The principle of operation resembles that of the Cathode Ray Tube (CRT) but on a much smaller length scale. The production of displays with low energy consumption could be accomplished using CNT.
In the modern communication technology traditional analog electrical devices are increasingly replaced by optical or Optoelectronic devices due to their enormous bandwidth and capacity, respectively. Two promising examples are Photonic Crystals and Quantum Dots. Photonic crystals are materials with a periodic variation in the refractive index with a lattice constant that is half the wavelength of the light used. They offer a selectable energy band gap for the propagation of a certain wavelength. Thus they resemble a semiconductor, though not for electrons, but for Photons. Nanolithography is that branch of nanotechnology, which deals with the study and application of fabrication of nanoscale structures like semiconductor circuits. As of 2007, Nanolithography has been is a very active area of research in academia and in industry.
Quantum Computers use the Laws of Quantum Mechanics for computing fast quantum Algorithms. The Quantum computer has quantum bit memory space termed “Qubit” for several computations at the same time. This facility may improve the performance of the older systems.
An inevitable use of nanotechnology will be in heavy industry. Lighter and stronger materials will be of immense use to aircraft manufacturers, leading to increased performance. Spacecraft will also benefit, where weight is a major factor. Nanotechnology would help to reduce the size of equipment and thereby decrease fuel-consumption required to get it airborne.
Another useful application is Nanobatteries. Because of the relatively low energy density of batteries the operating time is limited and a replacement or recharging is needed. The huge number of spent batteries and accumulators represent a disposal problem. The use of batteries with higher energy content or the use of rechargeable batteries or Super- capacitors with higher rate of recharging using Nanomaterials could be helpful for the battery disposal problem.
The most prominent application of nanotechnology in the household is self-cleaning or “easy-to-clean” surfaces on ceramics or glasses. Nanoceramic particles have improved the smoothness and heat resistance of common household equipment such as the flat iron. The use of engineered nanofibers already makes clothes water- and stain-repellent or wrinkle-free. Textiles with a nanotechnological ‘finish’ can be washed less frequently and at lower temperatures. Nanotechnology has been used to integrate tiny carbon particles membrane and guarantee full-surface protection from electrostatic charges for the wearer.
New foods are among the nanotechnology-created consumer products coming onto the market at the rate of 3 to 4 per week, according to the ‘Project on emerging Technologies’ (PEN), based on an inventory it has drawn up of 609 known or claimed nano-products. On PEN’s list are three foods — a brand of canola cooking oil called Canola Active Oil, a tea called Nanotea and a chocolate diet shake called Nanoceuticals Slim Shake Chocolate. According to company information posted on PEN’s Web site, the canola oil, by Shemen Industries of Israel, contains an additive called “nanodrops” designed to carry vitamins, minerals and phytochemicals through the digestive system and urea. The shake, according to U.S. manufacturer RBC Life Sciences Inc., uses cocoa infused “NanoClusters” to enhance the taste and health benefits of cocoa without the need for extra sugar.
The joint use of Nanoelectronics, Photolithography and new biomaterials provides a possible approach to manufacturing Nanorobots for common medical applications, such as for surgical instrumentation, diagnosis and drug delivery. Nanorobotics is the technology of creating machines or Robots at or close to the microscopic scale of a Nanometer (10−9 meter). Another definition is a robot that allows precision interactions with nanoscale objects, or can manipulate with nanoscale resolution. Following this definition even a large apparatus such as an Atomic Force Microscope (AFM) can be considered as a Nanorobotic instrument when configured to perform Nanomanipulation. Also, macro-scale robots or microrobots that can move with nanoscale precision can also be considered Nanorobots. Nanomachines are largely in the research-and-development phase, but some primitive molecular machines have been tested. An example is a sensor having a switch approximately 1.5 nanometers across, capable of counting specific molecules in a chemical sample.
There has been much debate on the future implications of Nanotechnology. Nanotechnology has the potential to create many new materials and devices with a vast range of applications. On the other hand, nanotechnology raises many of issues as with the introduction of any new technology, including concerns about the toxicity and environmental impact of Nanomaterials and their potential effects on global economics. These concerns have led to a debate among advocacy groups and governments on whether special regulations on Nanotechnology are warranted. Calls for tighter regulation of nanotechnology have occurred alongside a growing debate related to the human health and safety risks associated with nanotechnology. Reflecting the challenges for ensuring responsible life cycle regulation, the “Institute for food and Agriculture Standards” has proposed that, the standards for nanotechnology research and development should be integrated across consumer, worker and environmental standards. They also propose that NGOs and other citizen groups play a meaningful role in the development of these standards.
So what does this all mean? Right now, it means that scientists are experimenting with substances at the nanoscale to learn about their properties and how we might be able to take advantage of them in various applications. Engineers are trying to use nano-size wires to create smaller, more powerful microprocessors. Doctors are searching for ways to use nanoparticles in medical applications. Still, we’ve got a long way to go before nanotechnology dominates the technology and medical markets.