Introduction

How big is a nanometer? By definition, a nanometer, abbreviated as nm, is a unit for length that measures one billionth of a meter. (1 nm = 10 −3 μm = 10 –6 mm = 10 −7 cm = 10 −9 m.) Our hair is visible to the naked eye. Using an optical microscope we can measure the diameter of our hair, which is in the range of 20–50 microns (μm) or 20 000–50 000 nm. Blood cells are not visible to the naked eye, but they can be seen under the microscope, revealing a diameter of about 10 microns or 10 000 nm. The diameter of hydrogen atoms is 0.1 nm. In other words 10 hydrogen atoms can be placed side-by-side in 1 nm. Figure 1.1 provides an excellent illustration of the relative scales in nature. The discovery of nanomaterials ushered us to a new era of materials. We have progressed from the microworld to the nanoworld. What is nanotechnology? According to the National Science Foundation in the United States nanotechnology is defined as [1]: Research and technology development at the atomic, molecular or macromolecular levels, in the length scale of approximately 1–100 nanometer range, to provide a fundamental understanding of phenomena and materials at the nanoscale and to create and use structures, devices and systems that have novel properties and functions because of their small and/or intermediate size. The novel and differentiating properties and functions are developed at a critical length scale of matter typically under 100 nm. Nanotechnology research and development includes manipulation under control of the nanoscale structures and their integration into larger material components, systems and architectures. Within these larger scale assemblies, the control and construction of their structures and components remains at the nanometer scale.

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