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Nanotechnology is the engineering of functionalsystems at the molecular scale. This covers bothcurrent work and concepts that are more advanced.

In its original sense, 'nanotechnology' refers to theprojected ability to construct items from the bot-tom up, using techniques and tools being devel-oped today to make complete, high performanceproducts.

Generally nanotechnology deals with structuressized between 1 to 100 nanometer in at least onedimension, and involves developing materials ordevices within that size.

Nanotechnology is very diverse, ranging from ex-tensions of conventional device physics to com-pletely new approaches based upon molecular self-assembly, from developing new materials with di-mensions on the nanoscale to investigatingwhether we can directly control matter on theatomic scale.

There has been much debate on the future impli-cations of nanotechnology. Nanotechnology hasthe potential to create many new materials anddevices with a vast range of applications, such asin medicine, electronics, biomaterials and energyproduction. On the other hand, nanotechnologyraises many of the same issues as with any intro-duction of new technology, including concernsabout the toxicity and environmental impact ofnanomaterials, and their potential effects on glo-bal economics, as well as speculation about vari-ous doomsday scenarios. These concerns have ledto a debate among advocacy groups and govern-ments on whether special regulation ofnanotechnology is warranted.

BackgroundThe first use of the concepts found in 'nano-tech-nology' (but pre-dating use of that name) was in"There's Plenty of Room at the Bottom," a talk

Civil Services Main Examination 2010Special Study Package

(Nanotechnology)given by physicist Richard Feynman at an Ameri-can Physical Society meeting at Caltech on De-cember 29, 1959. Feynman described a process bywhich the ability to manipulate individual atomsand molecules might be developed, using one setof precise tools to build and operate another pro-portionally smaller set, and so on down to theneeded scale.

In the course of this, he noted, scaling issues wouldarise from the changing magnitude of variousphysical phenomena: gravity would become lessimportant, surface tension and van der Waals at-traction would become increasingly more signifi-cant, etc. This basic idea appeared plausible, andexponential assembly enhances it with parallelismto produce a useful quantity of end products.

The term "nanotechnology" was defined by TokyoScience University Professor Norio Taniguchi in a1974 paper as follows: "'Nano-technology' mainlyconsists of the processing of, separation, consoli-dation, and deformation of materials by one atomor by one molecule." In 2000, the United StatesNational Nanotechnology Initiative was foundedto coordinate Federal nanotechnology research anddevelopment and is evaluated by the President'sCouncil of Advisors on Science and Technology.

Nanotechnology ApplicationsWith nanotechnology, a large set of materials andimproved products rely on a change in the physi-cal properties when the feature sizes are shrunk.Nanoparticles, for example, take advantage of theirdramatically increased surface area to volume ra-tio. Their optical properties, e.g. fluorescence, be-come a function of the particle diameter. Whenbrought into a bulk material, nanoparticles canstrongly influence the mechanical properties of thematerial, like stiffness or elasticity.

For example, traditional polymers can be reinforcedby nanoparticles resulting in novel materials which

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can be used as lightweight replacements for met-als. Therefore, an increasing societal benefit of suchnanoparticles can be expected.

Such nanotechnologically enhanced materials willenable a weight reduction accompanied by an in-crease in stability and improved functionality.Practical nanotechnology is essentially the increas-ing ability to manipulate (with precision) matteron previously impossible scales, presenting possi-bilities which many could never have imagined -it therefore seems unsurprising that few areas ofhuman technology are exempt from the benefitswhich nanotechnology could potentially bring.

MedicineThe biological and medical research communitieshave exploited the unique properties ofnanomaterials for various applications (e.g., con-trast agents for cell imaging and therapeutics fortreating cancer). Terms such as biomedicalnanotechnology, nanobiotechnology, andnanomedicine are used to describe this hybrid field.Functionalities can be added to nanomaterials byinterfacing them with biological molecules orstructures.

The size of nanomaterials is similar to that of mostbiological molecules and structures; therefore,nanomaterials can be useful for both in vivo andin vitro biomedical research and applications. Thusfar, the integration of nanomaterials with biologyhas led to the development of diagnostic devices,contrast agents, analytical tools, physical therapyapplications, and drug delivery vehicles.

DiagnosticsNanotechnology-on-a-chip is one more dimensionof lab-on-a-chip technology. Magneticnanoparticles, bound to a suitable antibody, areused to label specific molecules, structures or mi-croorganisms. Gold nanoparticles tagged with shortsegments of DNA can be used for detection of ge-netic sequence in a sample. Multicolor optical cod-ing for biological assays has been achieved by em-bedding different-sized quantum dots into poly-meric microbeads. Nanopore technology for analy-sis of nucleic acids converts strings of nucleotidesdirectly into electronic signatures.

Drug DeliveryNanotechnology has been a boom in medical fieldby delivering drugs to specific cells usingnanoparticles. The overall drug consumption andside-effects can be lowered significantly by depos-iting the active agent in the morbid region onlyand in no higher dose than needed. This highlyselective approach reduces costs and human suf-fering. An example can be found in dendrimersand nanoporous materials. Another example is touse block co-polymers, which form micelles fordrug encapsulation. They could hold small drugmolecules transporting them to the desired loca-tion.

Another vision is based on small electromechani-cal systems; NEMS are being investigated for theactive release of drugs. Some potentially impor-tant applications include cancer treatment withiron nanoparticles or gold shells. A targeted or per-sonalized medicine reduces the drug consumptionand treatment expenses resulting in an overall so-cietal benefit by reducing the costs to the publichealth system.

Nanotechnology is also opening up new opportu-nities in implantable delivery systems, which areoften preferable to the use of injectable drugs, be-cause the latter frequently display first-order ki-netics (the blood concentration goes up rapidly,but drops exponentially over time). This rapid risemay cause difficulties with toxicity, and drug effi-cacy can diminish as the drug concentration fallsbelow the targeted range.

Tissue EngineeringNanotechnology can help to reproduce or to re-pair damaged tissue. “Tissue engineering” makesuse of artificially stimulated cell proliferation byusing suitable nanomaterial-based scaffolds andgrowth factors. Tissue engineering might replacetoday’s conventional treatments like organ trans-plants or artificial implants. Advanced forms of tis-sue engineering may lead to life extension.

For patients with end-state organ failure, there maynot be enough healthy cells for expansion and

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transplantation into the ECM (extracellular ma-trix). In this case, pluripotent stem cells are needed.One potential source for these cells is iPS (inducedPluripontent Stem cells); these are ordinary cellsfrom the patients own body that are reprogrammedinto a pluripotent state, and has the advantage ofavoiding rejection (and the potentially life-threat-ening complications associated with immunosup-pressive treatments).

Another potential source of pluripotent cells isfrom embryos, but this has two disadvantages: 1)It requires that we solve the problem of cloning,which is technically very difficult (especially pre-venting abnormalities). 2) It requires the harvest-ing of embryos. Given that each one of us was oncean embryo, this source is claimed by some to beethically problematic.

Chemistry And EnvironmentChemical catalysis and filtration techniques are twoprominent examples where nanotechnology al-ready plays a role. The synthesis provides novelmaterials with tailored features and chemical prop-erties: for example, nanoparticles with a distinctchemical surrounding (ligands), or specific opticalproperties. In this sense, chemistry is indeed a ba-sic nanoscience. In a short-term perspective, chem-istry will provide novel “nanomaterials” and in thelong run, superior processes such as “self-assem-bly” will enable energy and time preserving strat-egies. In a sense, all chemical synthesis can be un-derstood in terms of nanotechnology, because ofits ability to manufacture certain molecules. Thus,chemistry forms a base for nanotechnology pro-viding tailor-made molecules, polymers, etcetera,as well as clusters and nanoparticles.

CatalysisChemical catalysis benefits especially fromnanoparticles, due to the extremely large surfaceto volume ratio. The application potential ofnanoparticles in catalysis ranges from fuel cell tocatalytic converters and photocatalytic devices.Catalysis is also important for the production ofchemicals.

Platinum nanoparticles are now being considered

in the next generation of automotive catalytic con-verters because the very high surface area ofnanoparticles could reduce the amount of plati-num required. However, some concerns have beenraised due to experiments demonstrating that theywill spontaneously combust if methane is mixedwith the ambient air. Ongoing research at the Cen-tre National de la Recherche Scientifique (CNRS)in France may resolve their true usefulness for cata-lytic applications. Nanofiltration may come to bean important application, although future researchmust be careful to investigate possible toxicity.

FiltrationA strong influence of photochemistry on waste-water treatment, air purification and energy stor-age devices is to be expected. Mechanical or chemi-cal methods can be used for effective filtration tech-niques. One class of filtration techniques is basedon the use of membranes with suitable hole sizes,whereby the liquid is pressed through the mem-brane. Nanoporous membranes are suitable for amechanical filtration with extremely small poressmaller than 10 nm (“nanofiltration”) and may becomposed of nanotubes. Nanofiltration is mainlyused for the removal of ions or the separation ofdifferent fluids.

On a larger scale, the membrane filtration tech-nique is named ultrafiltration, which works downto between 10 and 100 nm. One important field ofapplication for ultrafiltration is medical purposesas can be found in renal dialysis. Magneticnanoparticles offer an effective and reliable methodto remove heavy metal contaminants from wastewater by making use of magnetic separation tech-niques. Using nanoscale particles increases the ef-ficiency to absorb the contaminants and is com-paratively inexpensive compared to traditional pre-cipitation and filtration methods.

Some water-treatment devices incorporatingnanotechnology are already on the market, withmore in development. Low-cost nanostructuredseparation membranes methods have been shownto be effective in producing potable water in a re-cent study.

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EnergyThe most advanced nanotechnology projects re-lated to energy are: storage, conversion, manufac-turing improvements by reducing materials andprocess rates, energy saving (by better thermal in-sulation for example), and enhanced renewableenergy sources.

Reduction of EnergyConsumption

A reduction of energy consumption can be reachedby better insulation systems, by the use of moreefficient lighting or combustion systems, and byuse of lighter and stronger materials in the trans-portation sector. Currently used light bulbs onlyconvert approximately 5% of the electrical energyinto light. Nanotechnological approaches like light-emitting diodes (LEDs) or quantum caged atoms(QCAs) could lead to a strong reduction of energyconsumption for illumination.

Increasing the Efficiency ofEnergy Production

Today's best solar cells have layers of several dif-ferent semiconductors stacked together to absorblight at different energies but they still only man-age to use 40 percent of the Sun's energy. Com-mercially available solar cells have much lowerefficiencies (15-20%). Nanotechnology could helpincrease the efficiency of light conversion by us-ing nanostructures with a continuum of bandgaps.

The degree of efficiency of the internal combus-tion engine is about 30-40% at the moment.Nanotechnology could improve combustion bydesigning specific catalysts with maximized sur-face area. In 2005, scientists at the University ofToronto developed a spray-on nanoparticle sub-stance that, when applied to a surface, instantlytransforms it into a solar collector.

More Environmentally FriendlyEnergy Systems

An example for an environmentally friendly formof energy is the use of fuel cells powered by hy-drogen, which is ideally produced by renewable

energies. Probably the most prominentnanostructured material in fuel cells is the catalystconsisting of carbon supported noble metal par-ticles with diameters of 1-5 nm. Suitable materialsfor hydrogen storage contain a large number ofsmall nanosized pores.

Therefore many nanostructured materials likenanotubes, zeolites or alanates are under investi-gation. Nanotechnology can contribute to the fur-ther reduction of combustion engine pollutants bynanoporous filters, which can clean the exhaustmechanically, by catalytic converters based onnanoscale noble metal particles or by catalytic coat-ings on cylinder walls and catalytic nanoparticlesas additive for fuels.

Recycling of BatteriesBecause of the relatively low energy density ofbatteries the operating time is limited and a re-placement or recharging is needed. The huge num-ber of spent batteries and accumulators representa disposal problem. The use of batteries with higherenergy content or the use of rechargeable batter-ies or supercapacitors with higher rate of recharg-ing using nanomaterials could be helpful for thebattery disposal problem.

Information andCommunication

Current high-technology production processes arebased on traditional top down strategies, wherenanotechnology has already been introduced si-lently. The critical length scale of integrated cir-cuits is already at the nanoscale (50 nm and be-low) regarding the gate length of transistors inCPUs or DRAM devices.

Memory StorageElectronic memory designs in the past have largelyrelied on the formation of transistors. However,research into crossbar switch based electronics haveoffered an alternative using reconfigurable inter-connections between vertical and horizontal wir-ing arrays to create ultra high density memories.Two leaders in this area are Nantero which hasdeveloped a carbon nanotube based crossbar

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memory called Nano-RAM and Hewlett-Packardwhich has proposed the use of memristor materialas a future replacement of Flash memory.

Novel SemiconductorDevices

An example of such novel devices is based onspintronics.The dependence of the resistance of amaterial (due to the spin of the electrons) on anexternal field is called magnetoresistance. This ef-fect can be significantly amplified (GMR - GiantMagneto-Resistance) for nanosized objects, forexample when two ferromagnetic layers are sepa-rated by a nonmagnetic layer, which is severalnanometers thick (e.g. Co-Cu-Co).

The GMR effect has led to a strong increase in thedata storage density of hard disks and made thegigabyte range possible. The so called tunnelingmagnetoresistance (TMR) is very similar to GMRand based on the spin dependent tunneling of elec-trons through adjacent ferromagnetic layers. BothGMR and TMR effects can be used to create a non-volatile main memory for computers, such as theso called magnetic random access memory orMRAM.

In 1999, the ultimate CMOS transistor developedat the Laboratory for Electronics and InformationTechnology in Grenoble, France, tested the limitsof the principles of the MOSFET transistor with adiameter of 18 nm (approximately 70 atoms placedside by side).

Novel OptoelectronicDevices

In the modern communication technology tradi-tional analog electrical devices are increasinglyreplaced by optical or optoelectronic devices dueto their enormous bandwidth and capacity, respec-tively. Two promising examples are photonic crys-tals and quantum dots. Photonic crystals are ma-terials with a periodic variation in the refractiveindex with a lattice constant that is half the wave-length of the light used.

They offer a selectable band gap for the propaga-tion of a certain wavelength, thus they resemble a

semiconductor, but for light or photons instead ofelectrons. Quantum dots are nanoscaled objects,which can be used, among many other things, forthe construction of lasers. The advantage of a quan-tum dot laser over the traditional semiconductorlaser is that their emitted wavelength depends onthe diameter of the dot. Quantum dot lasers arecheaper and offer a higher beam quality than con-ventional laser diodes.

DisplaysThe production of displays with low energy con-sumption could be accomplished using carbonnanotubes (CNT). Carbon nanotubes are electri-cally conductive and due to their small diameterof several nanometers, they can be used as fieldemitters with extremely high efficiency for fieldemission displays (FED). The principle of opera-tion resembles that of the cathode ray tube, buton a much smaller length scale.

Quantum ComputersEntirely new approaches for computing exploit thelaws of quantum mechanics for novel quantumcomputers, which enable the use of fast quantumalgorithms. The Quantum computer has quantumbit memory space termed "Qubit" for several com-putations at the same time. This facility may im-prove the performance of the older systems.

Heavy IndustryAn inevitable use of nanotechnology will be inheavy industry.

AerospaceLighter and stronger materials will be of immenseuse to aircraft manufacturers, leading to increasedperformance. Spacecraft will also benefit, whereweight is a major factor. Nanotechnology wouldhelp to reduce the size of equipment and therebydecrease fuel-consumption required to get it air-borne.

Hang glidermjs may be able to halve their weightwhile increasing their strength and toughnessthrough the use of nanotech materials. Nanotech

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is lowering the mass of supercapacitors that willincreasingly be used to give power to assistive elec-trical motors for launching hang gliders off flatlandto thermal-chasing altitudes.

ConstructionNanotechnology has the potential to make con-struction faster, cheaper, safer, and more varied.Automation of nanotechnology construction canallow for the creation of structures from advancedhomes to massive skyscrapers much more quicklyand at much lower cost.

RefineriesUsing nanotech applications, refineries producingmaterials such as steel and aluminium will be ableto remove any impurities in the materials they cre-ate.

Vehicle ManufacturersMuch like aerospace, lighter and stronger materi-als will be useful for creating vehicles that are bothfaster and safer. Combustion engines will also ben-efit from parts that are more hard-wearing andmore heat-resistant.

Consumer GoodsNanotechnology is already impacting the field ofconsumer goods, providing products with novelfunctions ranging from easy-to-clean to scratch-resistant. Modern textiles are wrinkle-resistant andstain-repellent; in the mid-term clothes will be-come “smart”, through embedded “wearable elec-tronics”. Already in use are different nanoparticleimproved products. Especially in the field of cos-metics, such novel products have a promising po-tential.

FoodsComplex set of engineering and scientific chal-lenges in the food and bioprocessing industry formanufacturing high quality and safe food throughefficient and sustainable means can be solvedthrough nanotechnology. Bacteria identificationand food quality monitoring using biosensors; in-telligent, active, and smart food packaging systems;

nanoencapsulation of bioactive food compounds arefew examples of emerging applications ofnanotechnology for the food industry.

Nanotechnology can be applied in the production,processing, safety and packaging of food. Ananocomposite coating process could improve foodpackaging by placing anti-microbial agents directlyon the surface of the coated film. Nanocompositescould increase or decrease gas permeability of dif-ferent fillers as is needed for different products.They can also improve the mechanical and heat-resistance properties and lower the oxygen trans-mission rate. Research is being performed to applynanotechnology to the detection of chemical andbiological substances for sensanges in foods.

Nano-FoodsNew foods are among the nanotechnology-createdconsumer products coming onto the market at therate of 3 to 4 per week, according to the Project onEmerging Nanotechnologies (PEN), based on aninventory it has drawn up of 609 known or claimednano-products.

On PEN's list are three foods -- a brand of canolacooking oil called Canola Active Oil, a tea calledNanotea and a chocolate diet shake calledNanoceuticals Slim Shake Chocolate.

HouseholdThe most prominent application of nanotechnologyin the household is self-cleaning or “easy-to-clean”surfaces on ceramics or glasses. Nanoceramic par-ticles have improved the smoothness and heat re-sistance of common household equipment such asthe flat iron.

OpticsThe first sunglasses using protective and anti-re-flective ultrathin polymer coatings are on the mar-ket. For optics, nanotechnology also offers scratchresistant surface coatings based on nanocomposites.Nano-optics could allow for an increase in preci-sion of pupil repair and other types of laser eyesurgery.

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TextilesThe use of engineered nanofibers already makes clothes water- and stain-repellent or wrinkle-free. Tex-tiles 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-surfaceprotection from electrostatic charges for the wearer. Many other applications have been developed byresearch institutions such as the Textiles Nanotechnology Laboratory at Cornell University

CosmeticsOne field of application is in sunscreens. The traditional chemical UV protection approach suffers from itspoor long-term stability. A sunscreen based on mineral nanoparticles such as titanium dioxide offer severaladvantages. Titanium oxide nanoparticles have a comparable UV protection property as the bulk material,but lose the cosmetically undesirable whitening as the particle size is decreased.

AgricultureApplications of nanotechnology have the potential to change the entire agriculture sector and food indus-try chain from production to conservation, processing, packaging, transportation, and even waste treat-ment. NanoScience concepts and Nanotechnology applications have the potential to redesign the produc-tion cycle, restructure the processing and conservation processes and redefine the food habits of the people.

Major Challenges related to agriculture like Low productivity in cultivable areas, Large uncultivableareas,Shrinkage of cultivable lands, Wastage of inputs like water, fertilizers, pesticides, Wastage of prod-ucts and of course Food security for growing numbers can be addressed through various applications ofnanotechnology.

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