imagine a world where microscopic medical implants patrol our arteries, diagnosing ailments and fighting disease; where military battle-suits deflect explosions; where computer chips are no bigger than specks of dust; and where clouds of miniature space probes transmit data from the atmospheres of Mars or Titan.
Many incredible claims have been made about the future's nanotechnological applications, but what exactly does nano mean, and why has controversy plagued this emerging technology?
Nanotechnology is science and engineering at the scale of atoms and molecules. It is the manipulation and use of materials and devices so tiny that nothing can be built any smaller.
How small is small?
Nanomaterials are typically between 0.1 and 100 nanometres (nm) in size - with 1 nm being equivalent to one billionth of a metre (10-9 m).
This is the scale at which the basic functions of the biological world operate - and materials of this size display unusual physical and chemical properties. These profoundly different properties are due to an increase in surface areacompared to volume as particles get smaller - and also the grip of weird quantum effects at the atomic scale.
If 1 nanometre was roughly the width of a pinhead, then 1 metre on this scale would stretch the entire distance from Washington, DC to Atlanta - around 1000 kilometres. But a pinhead is actually one million nanometres wide. Most atoms are 0.1 to 0.2 nm wide, strands of DNA around 2 nm wide, red blood cells are around 7000 nm in diameter, while human hairs are typically 80,000 nm across.
Unwittingly, people have made use of some unusual properties of materials at the nanoscale for centuries. Tiny particles of gold for example, can appear red or green - a property that has been used to colour stained glass windows for over 1000 years.
Nanotechnology is found elsewhere today in products ranging from nanometre-thick films on "self-cleaning" windows to pigments in sunscreens and lipsticks.
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