What are nanotechnologies?

Defining nanotechnologies

Nanotechnology has now become an umbrella term used to encompass the study, manipulation and application of matter based on its properties at the atomic scale. The "nano" prefix derives from the Greek noun nanos, meaning dwarf. A nanometre (nm) is one billionth (1 x 10-9) of a metre: the length of about ten atoms placed side-by-side, or 1/80,000th of the thickness of a human hair. Nanotechnology is now generally considered to relate to the organisation of atoms and molecules within a size range of 1 to 100+ nm, although much larger structures, devices and systems that incorporate or owe their existence to such entities are also described as nanotechnological.

Some definitions differentiate between nanoscience and nanotechnologies. The Royal Society & The Royal Academy of Engineering have agreed on the following definitions:

"Nanoscience is the study of phenomena and manipulation of materials at atomic, molecular and macromolecular scales, where properties differ significantly from those at a larger scale.

Nanotechnologies are the design, characterisation, production and application of structures, devices and systems by controlling shape and size at nanometre scale"

Nanotechnologies: past, present and future

For more than a century, chemists have been learning to control the arrangement of small numbers of atoms inside molecules, bringing an ability to create more effective drugs, high-performance plastics and other purpose-designed materials. Major technological advances over the past few decades have also permitted a progressive downsizing of products - notably in the area of electronics - reducing materials consumption, saving energy and cutting costs, while also greatly expanding functionality. Transition to the "nano-domain" nevertheless remains a giant step. Despite major advances in recent years, much remains to be learned about the aggregation of atoms and molecules at the lowest level.

Size does matter

The reason for the widespread interest in this field is that materials can exhibit very different behaviour at the nano-scale to that observed in the mass. At sizes below 100 nm, the quantum-size effect prevails, so properties are determined by quantum mechanics rather than the classical mechanics that govern matter at the macro- and even micro-scale.
Fundamental characteristics such as electrical conductivity, colour, strength and melting point are all subject to change. Because of their very small size, nano-particles also have a relatively huge surface area, making them ideal for use as absorbers, sensors and catalysts. Glass and ceramics are two long established materials that depend upon nano-scale properties, while photography is a more recent process that unknowingly employed such effects.
With deliberate and concerted efforts to tailor the structure of materials at the nanoscale, it will become possible to engineer novel materials that have entirely new properties never before identified in nature.

Dawn of a new age

Today, the nanotechnology revolution is still at a very early stage. Most applications to date can be described as ‘bulk nanotechnology’ – i.e. the commercial-scale production of ultra-thin films and nano-sized particles, such as metal oxides and clays. This alone is already bringing many significant advances.
Examples include:

• Zinc oxide, used to provide UV protection in sun creams. When reduced to nanosize, the particles become transparent and are thus more cosmetically appealing than the traditional white product;
  
• Particles for improving lacquers and paints to provide better protection of surfaces against scratching, soiling or algae coverage;
  
• Self-cleaning or self-sterilising surfaces with important applications in the food industry and healthcare.
  
• Medical devices and implants, with surfaces modified through nanotechnology to reduce rejection rates. Functionalised nanoparticles also have the potential to accumulate in tumour cells, making them more accessible for treatment;
  
• High-density data storage media making use of the major magnetoresistive properties of nano-scale granular magnetic materials.
  
• Carbon fullerenes – nanotubes and ‘buckyballs’ – are a further particularly exciting class of materials. Many times stronger and lighter than steel, and able to act as electrical conductors or semiconductors, they will open the door to a huge range of applications once methods have been developed to manufacture them inexpensively in industrial quantities

The text is based on an excerpt from "Nanotechnologies: past, present and future", and can be found in "Setting the nanotechnology research agenda", European Industrial Research magazine, December 2003, p. 7 - p. 10 (online available here as pdf)