Chris Powitzky and Mark Buchanan

What is Nanotechnology?

Nanotechnology is currently all the rage. Accordingly, both the term and the concept are much over-used. Nevertheless few people, and even fewer designers, really know what nanotechnology actually is and what it is good for. It is, however, most definitely more than just a passing fashion. In fact, at present nanotechnology is still a fledging science but one that has been forecast an extremely promising future with the potential to change the world around us. 

"Nano" derives from the Greek word nanos (Latin nanus) meaning "dwarf - so begin many articles on nanotechnology and this book is no exception. A nanometre (nm) is a millionth of a millimetre (1/1,000,000mm = lO'^mm) or a billionth of a metre (1/1,000,000,000m = IQ-^m). It is an 80,000th of the diameter of a hair (the figure varies between 50,000th and 100,000th) and is the same size as about five to ten atoms. Given that a billion nanometers equal a metre, it should be clear that we are concerned here with the most minute of dimensions. The wavelength range of visible light is approximately 400 to 800 nm and as the light scattered by smaller particles reduces significantly, particles of such a small size become effectively invisible. "Nano" cannot, therefore, be seen with the naked eye. 

Comparisons help us to better comprehend the scale of the dimensions involved - a common comparison is that the proportion of a nanometre to a football is about the same as that of a football to the earth. If one were to spread a single drop of water over an area of 1 m^ it would be 1 nm thick. Human fingernails grow at a rate of I nm per second.

In the famous film "Powers of Ten" by the designer-duo Charles and Ray Eames, a classic film in the field that has now attained cult status, the viewer is taken on a journey through the powers of ten of the cosmos, illustrating the differences in dimension. The film, made in 1977, is most worthwhile and can still be ordered from the Eames Office in the USA via the internet.

 A clear and generally applicable description on an international level has not as yet been defined for the term "nanotechnology", but in most cases it serves as a general heading for all manner of analyses and material investigations at nanoscale. Generally speaking, nanotechnology therefore describes any activities at a magnitude of less than 100 nm. This threshold reflects the fact that at this point there is a "kink in nature". It is at this size that the properties of solid materials change, for example gold changes its colour to red. At 100 nm and below things start to become particularly interesting. 

The definition given by the German Federal Ministry of Education and Research (BMBF) summarises nanotechnology as follows: "Nanotechnology refers to the creation, investigation and application of structures, molecular materials, internal interfaces or surfaces with at least one critical dimension or with manufacturing tolerances of (typically) less than 100 nanometres. The decisive factor is that the very nanoscale of the system components results in new functionalities and properties for improving products or developing new products and applications."

"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 100nm. 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. In some particular cases, the critical length scale for novel properties and phenomena may be under Inm (e.g., manipulation of atoms at ~ 0.1 nm) or be larger than 100nm (e.g., nanoparticle reinforced polymers have the unique feature at ~ 200-300 nm as a function of the local bridges or bonds between the nanoparticles and the polymer)."

Nanoparticles measure only a few nanometres and can consist of just a few or several thousand atoms. The material out of which nanoparticles are made is nothing out of the ordinary. The basic material of nanoparticles can be organic or inorganic, for example silver or ceramic. They can be elements such as carbon, or compounds such as oxides, or they can be a combination of different compounds and elements. The key characteristic is not the material itself but the size of the particles. In comparison to their size nanoparticles have a vast surface area. At this size, a relatively inert material can become highly reactive and therefore potentially interesting for many different uses, for example as a catalyst. In addition nanoparticles have a tendency to form agglomerations. Nanoparticles with less than 1000 atoms, i.e. very small nanoparticles, are called clusters.

Nanoparticles are invisible due to the fact that they are smaller than the wavelength of visible light and therefore unable to scatter light. For this reason, a solution that contains a 60% proportion of solids in the form of nanoparticles can still be transparent.

Aside from synthetic production, nanoparticles are also present in natural materials, for example in clay, a constituent of loam, which contains a high proportion of natural nanoparticles. These are responsible for properties such as frost-resistance, durability and strength. Another example from nature is mother of pearl, whose high durability is also attributable to its nanostructure.

The ultra-thin and invisible nanocoatings, whose applications are of particular interest to designers, generally have a thickness of 5 lOnm. The optimum thickness of each coating, for instance when spray-applied, comes about automatically, a phenomenon that is termed "self-organisation". Each square centimetre then contains billions of nanoparticles.

The manufacture of such ultra-thin coatings with the help of chemical techniques uses a so-called "bottomup" approach, i.e. one develops from the smallest size to larger sizes, beginning with the atom and finishing with the desired product. By comparison, the conventional manufacture of raw materials generally uses a "top-down" approach, in which a material is reduced, for instance by grinding down, to the desired size. Nanotechnology in general, i.e. when used not solely for coatings, employs both such approaches. 

Nanoparticles can be used in solutions, which despite a high proportion of solids appear transparent. Another application is the use of nanopowders. Nanocoatings can be applied using traditional means such as spraying and dipping.

The shimmering blue colour of butterfly wings is caused by light reflections rather than colored pigments. The wings are covered with nanostructured scales that reflect light and through a process of interference cancel out all colors except blue. Such colourings are a product of the laws of physics and cannot fade. For this reason, researchers attempt to replicate this effect artificially with paints or colored films.

Gold nanoparticles are regarded as the ideal constituent material for nanostructures. Their unique optical, electronic and catalytic properties are especially interesting.

Examples of the Nanometer scale

Single-walled carbon nanotubes can be extruded to form macroscopic fibers. This image shows a single carbon nanotube isolated and enclosed In a molecule. Under particular conditions carbon nanotubes have been found to exhibit fluorescent properties. In the near infrared range, light is absorbed and emitted.