Types Of Nanotech

[Zoraida]

Nanotechnologycan increase the surface area of a material. This allows more atoms to interact with other materials. An increased surface area is one of the chief reasons nanometer-scale materials can be stronger, more durable, and more conductive than their larger-scale (called bulk) counterparts.

Nanotechnology is not microscopy. "Nanotechnology is not simply working at ever smaller dimensions," the U.S.-based National Nanotechnology Initiative says. "Rather, working at the nanoscale enables scientists to utilize the unique physical, chemical, mechanical, and optical properties of materials that naturally occur at that scale."

Tubular fullerenes are called nanotubes. Thanks to the way carbon atoms bond to each other, carbon nanotubes are remarkably strong and flexible. Carbon nanotubes are harder than diamond and more flexible than rubber.

Carbon nanotubes hold great potential for science and technology. The U.S. space agency NASA, for example, is experimenting with carbon nanotubes to produce "blacker than black" coloration on satellites. This would reduce reflection, so data collected by the satellite are not "polluted" by light.

Nanoparticles can include carbon, like fullerenes, as well as nanometer-scale versions of many other elements, such as gold, silicon, and titanium. Quantum dots, a type of nanoparticle, are semiconductors made of different elements, including cadmium and sulfur. Quantum dots have unusual fluorescent capabilities. Scientists and engineers have experimented with using quantum dots in everything from photovoltaic cells (used for solar power) to fabric dye.

The properties of nanoparticles have been important in the study of nanomedicine. One promising development in nanomedicine is the use of gold nanoparticles to fight lymphoma, a type of cancer that attacks cholesterol cells. Researchers have developed a nanoparticle that looks like a cholesterol cell, but with gold at its core. When this nanoparticle attaches to a lymphoma cell, it prevents the lymphoma from "feeding" off actual cholesterol cells, starving it to death.

Carbon nanotubes are often produced using a process called carbon assisted vapor deposition. (This is the process NASA uses to create its "blacker than black" satellite color.) In this process, scientists establish a substrate, or base material, where the nanotubes grow. Silicon is a common substrate. Then, a catalyst helps the chemical reaction that grows the nanotubes. Iron is a common catalyst. Finally, the process requires a heated gas, blown over the substrate and catalyst. The gas contains the carbon that grows into nanotubes.

Like buckyballs and some other nanomaterials, dendrimers have strong, cage-like cavities in their structure. Scientists and researchers are experimenting with dendrimers as multifunctional drug-delivery methods. A single dendrimer, for example, may deliver a drug to a specific cell, and also trace that drug's impact on the surrounding tissue.

Nanocomposites combine nanomaterials with other nanomaterials, or with larger, bulk materials. There are three main types of nanocomposites: nanoceramic matrix composites (NCMCs), metal matrix composites (MMCs), and polymer matrix composites (PMCs).

Industrial plastics are often composed of PMCs. One promising area of nanomedical research is creating PMC "tissue scaffolding." Tissue scaffolds are nanostructures that provide a frame around which tissue, such as an organ or skin, can be grown. This could revolutionize the treatment of burn injuries and organ loss.

Scientists and engineers working at the nanometer-scale need special microscopes. The atomic force microscope (AFM) and the scanning tunneling microscope (STM) are essential in the study of nanotechnology. These powerful tools allow scientists and engineers to see and manipulate individual atoms.

Top-down nanomanufacturing involves carving bulk materials to create features with nanometer-scale dimensions. For decades, the process used to produce computer chips has been top-down. Producers work to increase the speed and efficiency of each "generation" of microchip. The manufacture of graphene-based (as opposed to silicon-based) microchips may revolutionize the industry.

Bottom-up nanomanufacturing builds products atom-by-atom or molecule-by-molecule. Experimenting with quantum dots and other nanomaterials, tech companies are starting to develop transistors and other electronic devices using individual molecules. These atom-thick transistors may mark the future development of the microchip industry.

Modern nanotechnology truly began in 1981, when the scanning tunneling microscope allowed scientists and engineers to see and manipulate individual atoms. IBM scientists Gerd Binnig and Heinrich Rohrer won the 1986 Nobel Prize in Physics for inventing the scanning tunneling microscope. The Binnig and Rohrer Nanotechnology Center in Zurich, Switzerland, continues to build on the work of these pioneering scientists by conducting research and developing new applications for nanotechnology.

By the end of the 20th century, many companies and governments were investing in nanotechnology. Major nanotech discoveries, such as carbon nanotubes, were made throughout the 1990s. By the early 2000s, nanomaterials were being used in consumer products from sports equipment to digital cameras.

As early as the 4th century, Roman artists had discovered that adding gold and silver to glass created a startling effect: The glass appeared slate green when lit from the outside, but glowed red when lit from within. Nanoparticles of gold and silver were suspended in the glass solution, coloring it. The most famous surviving example of this technique is a ceremonial vessel, the Lycurgus Cup.

One of the most well-known examples of premodern use of nanomaterials is in European medieval stained-glass windows. Like the Romans before them, medieval artisans knew that by putting varying, small amounts of gold and silver in glass, they could produce bright reds and yellows.

Many governments, scientists, and engineers are researching the potential of nanotechnology to bring affordable, high-tech, and energy-efficient products to millions of people around the world. Nanotechnology has improved the design of products such as light bulbs, paints, computer screens, and fuels.

Nanotechnology is helping inform the development of alternative energy sources, such as solar and wind power. Solar cells, for instance, turn sunlight into electric currents. Nanotechnology could change the way solar cells are used, making them more efficient and affordable.

Solar cells, also called photovoltaic cells, are usually assembled as a series of large, flat panels. These solar panels are big and bulky. They are also expensive and often difficult to install. Using nanotechnology, scientists and engineers have been able to experiment with print-like development processes, which reduces manufacturing costs. Some experimental solar panels have been made in flexible rolls rather than rigid panels. In the future, panels might even be "painted" with photovoltaic technology.

The bulky, heavy blades on wind turbines may also benefit from nanotech. An epoxy containing carbon nanotubes is being used to make turbine blades that are longer, stronger, and lighter. Other nanotech innovations may include a coating to reduce ice buildup.

Nanotech is already helping increase the energy-efficiency of products. One of the United Kingdom's biggest bus operators, for instance, has been using a nano-fuel additive for close to a decade. Engineers mix a tiny amount of the additive with diesel fuel, and the cerium-oxide nanoparticles help the fuel burn more cleanly and efficiently. Use of the additive has achieved a 5 percent annual reduction in fuel consumption and emissions.

Nanomaterials can strip water of toxic metals and organic molecules. For example, researchers have discovered that nanometer-scale specks of rust are magnetic, which can help remove dangerous chemicals from water. Other engineers are developing nanostructured filters that can remove viruses from water.

Researchers are also experimenting with using nanotechnology to safely, affordably, and efficiently turn saltwater into freshwater, a process called desalination. In one experiment, nano-sized electrodes are being used to reduce the cost and energy requirements of removing salts from water.

One method uses nanoparticles' unique magnetic properties to help isolate oil. Oil itself is not magnetic, but when mixed with water-resistant iron nanoparticles, it can be magnetically separated from seawater. The nanoparticles can later be removed so the oil can be used.

Scientists and engineers are using nanotechnology to enhance clothing. By coating fabrics with a thin layer of zinc oxide nanoparticles, for instance, manufacturers can create clothes that give better protection from ultraviolet (UV) radiation, like that from the sun. Some clothes have nanoparticles in the form of little hairs or whiskers that help repel water and other materials, making fabric more stain-resistant.

Many cosmetic products contain nanoparticles. Nanometer-scale materials in these products provide greater clarity, coverage, cleansing, or absorption. For instance, the nanoparticles used in sunscreen (titanium dioxide and zinc oxide) provide reliable, extensive protection from harmful UV radiation. These nanomaterials offer better light reflection for a longer time period.

Carbon nanotubes, for example, are used to make bicycle frames and tennis rackets lighter, thinner, and more resilient. Nanotubes give golf clubs and hockey sticks a more powerful and accurate drive.

The food industry is using nanomaterials in both the packaging and agricultural sectors. Clay nanocomposites provide an impenetrable barrier to gases such as oxygen or carbon dioxide in lightweight bottles, cartons, and packaging films. Silver nanoparticles, embedded in the plastic of storage containers, kill bacteria.

Nanotech engineers have isolated and studied the way our taste buds perceive flavor. By targeting individual cells on a taste bud, nanomaterials can enhance the sweetness or saltiness of a particular food. A chemical nicknamed "bitter blocker," for instance, can trick the tongue into not tasting the naturally bitter taste of many foods.

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