Nanotech. : Secret Power With-in
What is so special at nano scale that is allowing the nanotech magic to happen?
Matter such as gases, liquids, and solids can exhibit unusual physical, chemical, and biological properties at the nanoscale, differing in important ways from the properties of bulk materials and single atoms or molecules. Some nanostructure materials are stronger or have different magnetic properties compared to other forms or sizes or the same material. Others are better at conducting heat or electricity. They may become more chemically reactive or reflect light better or change colour as their size or structure is altered.
The causes of these drastic changes stem from the world of ‘Quantum Physics’. The bulk properties of any material are merely the average of all the quantum forces affecting all the atoms. As you make things smaller and smaller, you eventually reach a point where the averaging no longer works.
The properties of materials can be different at the nanoscale for two main reasons:
· First, nanomaterials have a relatively larger surface area when compared to the same mass of material produced in a larger form. This can make materials more chemically reactive (in some cases materials that are inert in their larger form are reactive when produced in their nanoscale form), and affect their strength or electrical properties.
· Second, quantum effects can begin to dominate the behaviour of matter at the nanoscale – particularly at the lower end – affecting the optical, electrical and magnetic behaviour of materials. Materials can be produced that are nanoscale in one dimension (for example, very thin surface coatings), in two dimensions (for example, nanowires and nanotubes) or in all three dimensions (for example, nanoparticles)
The U.S. National Nanotechnology Initiative has large plans for nanotech. Mihail Roco, working with the organization, explains the group’s future plans by dividing their goals into four generations.
The first generation of nanotech is defined by passive structures that are created to carry out one specific task. Researchers are currently in this generation of the technology. The second generation is be defined by structures capable of multitasking. Researchers are currently entering this generation and hoping to further their abilities in the near future. The third generation will introduce systems composed of thousands of nanostructures. The fourth generation will be defined by nanosystems designed on the molecular level. These systems will work like living human or animal cells.
What if reaching down the nano scale would be as easy as zooming out?? Unfortunately this is not practically possible yet. Fabrication of nanomaterial requires different approach.
Top down approach works by miniaturizing strategy and involves lithographic patterning techniques. This is used for production of structures with long range orders. As component size is decreasing, physical limits of photolithography is becoming a problem for top down approach. Also, cost, heat dissipation problem in small geometries are adding on to the problems of top down approach. The solution to the limitations of top-down approach is its opposite Bottom-up approach. Bottom-up approach, inspired by nature, use chemical or physical forces operating at nanoscale to assemble basic units into a larger structure. Just like the nature’s way, Bottom-up approach uses concept of “Self-assembly”. Instead of taking away material to make structures, as done in Top-down approach, Bottom-up approach selectively adds atoms to create structures.
DNA Nanotechnology, classical chemical synthesis, dip pen nanolithography, Molecular self assembly are some of the techniques using Bottom-up approach.
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