Most of the researches done at present would contain the term “nano” or the related ones. Why is the technology in nanoscale so important? How are nanomaterials fabricated? How is it useful for us? and basically, What is Nanotechnology?
Nanotechnology is the science of manipulating matter at the atomic, and molecular levels to obtain materials with specifically enhanced chemical and physical properties. The prefix nano comes from the Greek word “Nanos” which means “dwarf”. Here, we specifically deal with 1-100 nm (1 nm or nanometer =10-9 meter, i.e. one billionth of a meter). How small is the nanoscale? Here are a few comparisons;
An average human hair is about 50,000-1,00,000 nm wide. If each person on Earth was of the size of a nanometer, everyone on the planet would fit into one hot wheel matchbox car. Your fingernail grows a nanometer every second.
The idea and concept behind nanotechnology started with a talk entitled “There’s Plenty of Room at the Bottom” by the physicist, Richard Feynman(the father of nanotechnology) at the American Physical Society meeting at the California Institute of Technology(CalTech) in 1959. But there are a number of relatively famous examples of ancient artifacts which were created using nanocomposites. The Lycurgus Cup, for example, is a stunning decorative Roman treasure.
It is made of a glass that changes colour when light is shown through it. Recently, scientists discovered the oldest known human-made nanomaterials in the “unique black coatings” of ancient pottery shards dated to 600 BC-unearthed from an archeological site in Keeladi, Tamil Nadu.
One of the parameters that is strongly connected to miniaturization and nanotechnology is the surface area to volume ratio. It increases with a decrease in the characteristic dimensions of a material, and vice versa. As the material size decreases, a greater portion of the atoms is found at the surface compared to those inside.
Thus, nanomaterials are more reactive than the same mass of materials made up of larger particles. The development of nanotechnology has been enabled by the invention of two tools that have revolutionized imaging and manipulation of nanoscaled objects; Scanning Tunneling Microscope(STM) in 1981 and Atomic Force Microscope(AFM) in 1985.
Nanostructures are often categorized as to how many of their dimensions fall in the nanoscale;
0-D nanostructures (nanoparticles and quantum dots), 1-D nanostructures (nanowires, quantum wires, nanorods and nanotubes), 2-D nanostructures (nanosheets, nano-thin films, planar quantum wells and superlattices), and 3-D nanostructures (bulk nanocrystalline films and nanocomposites).
Fabrication of nanoscale structure or devices can be achieved either by top-down or bottom-up
approach.
Top-down method : it is the fabrication method in which externally controlled tools are used to cut, mill and shape materials into the desired shape and order. Focused Ion Beam(FIB), Photolithography and Electron Beam Lithography (EBL) are the common techniques used in it.
Bottom-up method: self-assembly or bottom-up approaches of nanofabrication use chemical or physical forces operating at the nanoscale to assemble basic units into larger structures.
The pencil that we use contains graphite which consists of sheets of carbon in a hexagonal
lattice(graphene). Graphene is a 2D nanomaterial. The Morpho butterfly’s wings appear to be blue, despite containing no blue pigments at all. This is due to nanophotonic structures in their wings. Scientists are integrating plasmonic nanostructures with natural photonic architectures in Palladium-modified Morpho butterfly wings for sensitive hydrogen gas sensing.
Nanotechnology becomes a powerful new platform with a vast number of potential applications across a very wide number of practical applications including agriculture, diagnostic devices, new pharmaceuticals, medical imaging, biological sensors, and many others. But the health and safety effects of exposure to nanomaterials and what levels of exposure may be acceptable are not yet fully understood.
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