Abstract:
The word “nano” derives from the Latin word nanus meaning dwarf. The term is used in our metric system as a prefix to denote one billionth (10-9) of a quantity such as metre, kilogram, second etc.1 A nanometre is one billionth times smaller than a metre. In perspective, it is analogous to comparing the size of a mustard seed with respect to that of earth (see Figure 1.1). That is how small a nanometre is, so small that unless a powerful microscope is used, it cannot be perceived. A nanometre is used to measure things that are very small such as atoms and molecules, the smallest pieces of everything around us. For example, a human hair is about 100,000 nanometres wide (see Figure 1.2a), red blood cell is ~5000 nm, which is effectively ~5 μm in size (see Figure 1.2b), a DNA is 2 nm wide (see Figure 1.2c) and a water molecule is less than one nanometre. The European Commission defined nanomaterial as a material in an unbound state or as aggregate or as an agglomerate and for 50% or more of particles in the number size distribution having one or more external dimensions in the size range 1 nm – 100 nm.2
