What Is Nanotechnology?
Nanotechnology deals with the understanding and control of matter at dimensions between approximately 1 and 100 nanometers, where unique phenomena enable novel applications.
More specifically, nanotechnology is the imaging, modeling, measuring, design, characterization, production, and application of structures, devices, and systems by controlled manipulation of size and shape at the nanometer scale (atomic, molecular, and macromolecular scale) that produces structures, devices, and systems with at least one novel/superior characteristic or property.
The Nanoscale – How Small Is a Nano?
Dimensions between approximately 1 and 100 nanometers are known as the nanoscale. To see where 'nano' fits on the scale of things, check out our metric prefix table with examples and an interactive tutorial: View the Milky Way at 10 million light years from the Earth. Then move through space towards the Earth in successive orders of magnitude until you reach a tall oak tree. After that, begin to move from the actual size of a leaf into a microscopic world that reveals leaf cell walls, the cell nucleus, chromatin, DNA and finally, into the subatomic universe of electrons and protons.
Defining Nanotechnology (nan'o•tech•nol'o•gy) – It's Not That Simple...
One of the problems facing this technology is the confusion about how to define nanotechnology. Most revolve around the study and control of phenomena and materials at length scales below 100 nm and quite often they make a comparison with a human hair, which is about 50 000 to 100 000 nm wide.
For instance, in zero-dimensional (0D) nanomaterials all the dimensions are measured within the nanoscale (no dimensions are larger than 100 nm); in two-dimensional nanomaterials (2D), two dimensions are outside the nanoscale; and in three-dimensional nanomaterials (3D) are materials that are not confined to the nanoscale in any dimension. This class can contain bulk powders, dispersion of nanoparticles, bundles of nanowires, and nanotubes as well as multinanolayers.
Some definitions include a reference to molecular nanotechnology, and 'purists' argue that any definition needs to include a reference to "functional systems". The inaugural issue of Nature Nanotechnology asked 13 researchers from different areas what nanotechnology means to them and the responses, from enthusiastic to skeptical, reflect a variety of perspectives.
Another important criteria for the definition are the requirement that the nanostructure is man-made, i.e. a synthetically produced nanoparticle or nanomaterial. Otherwise, you would have to include every naturally formed biomolecule and material particle, in effect redefining much of chemistry and molecular biology as nanotech.
Who Coined the Term Nanotechnology?
The term was coined in 1974 by Norio Taniguichi of Tokyo Science University to describe semiconductor processes such as thin-film deposition that deal with control on the order of nanometers. His definition still stands as the basic statement today: "Nanotechnology mainly consists of the processing of separation, consolidation, and deformation of materials by one atom or one molecule."
Many argue that the history of nanotechnology starts with Richard Feynman's classic talk in December 1959: There's Plenty of Room at the Bottom - An Invitation to Enter a New Field of Physics:
The Significance of the Nanoscale – Why Does Nanotechnology Matter
Unusual physical, chemical, and biological properties can emerge in materials at the nanoscale. These properties may differ in important ways from the properties of bulk materials and single atoms or molecules.
The bulk properties of materials often change dramatically with nano ingredients. Composites made from particles of nano-size ceramics or metals smaller than 100 nanometers can suddenly become much stronger than predicted by existing materials-science models.
For example, metals with a so-called grain size of around 10 nanometers are as much as seven times harder and tougher than their ordinary counterparts with grain sizes in the hundreds of nanometers. The causes of these drastic changes stem from the weird world of quantum physics. The bulk properties of any material are merely the average of all the quantum forces affecting all the atoms. As you make things smaller and smaller, you eventually reach a point where the averaging no longer works.
The properties of materials can be different at the nanoscale for two main reasons:
Surface Area
First, nanomaterials have a relatively larger surface area when compared to the same mass of material produced in a larger form. This can make materials more chemically reactive (in some cases materials that are inert in their larger form are reactive when produced in their nanoscale form), and affect their strength or electrical properties.
Quantum Size Effects
Second, quantum effects can begin to dominate the behavior of matter at the nanoscale – particularly at the lower end – affecting the optical, electrical and magnetic behavior of materials. This effect describes the physics of electron properties in solids with great reductions in particle size. This effect does not come into play by going from macro to micro dimensions. However, it becomes dominant when the nanometer size range is reached.
We explain surface area and quantum size effects in detail in our explainer on why nanotechnology is so special.
The fascination with nanotechnology stems from these unique quantum and surface phenomena that matter exhibits at the nanoscale. They improve existing industrial processes, materials and applications in many fields – and allows entirely new ones.
Novel Nanotechnology Materials and Applications
There are different ways of manipulating matter at the nanoscale. The two notions you hear most are top-down and bottom-up methods. Briefly, that means that you make a nanomaterial either by taking a block of material and remove the bits and pieces you don't want until you get the shape and size you do want (that's top-down); or you use nature's self-organizing processes (that's called self-assembly) to build something from the bottom-up. The key to using self-assembly as a controlled and directed fabrication process lies in designing the components that are required to self-assemble into desired patterns and functions.
With regard to nanoscale materials, there are plenty of examples we could talk about here – nanoparticles, quantum dots, nanowires, nanofibers, ultrathin-films, MXenes, etc.
One example, though, that is exemplary of how an 'old' material gets an exciting new life through nanoscale technologies is the element carbon.
Natural carbon can exist in two very different types and is known to everyone: graphite and diamond. Three additional forms that were discovered between 1985 and 2004 have caused the current excitement among researchers about carbon nanomaterials – fullerenes, carbon nanotubes, and in particular graphene, often hyped as a 'wonder material'.
Current applications of nanomaterials include very thin coatings used, for example, in electronics and active surfaces (such as self-cleaning windows). In most applications the nanomaterial will be fixed or embedded but in some, such as those used in cosmetics and in some environmental remediation applications, free nanoparticles are used. The ability to engineer materials to very high precision and accuracy (smaller than 100 nm) is leading to considerable benefits in a wide range of industrial sectors, for instance in the production of components for the information and communication technology, automotive and aerospace industries.
Some 20-30 years ago, micro electro mechanical systems (MEMS) emerged in industrial manufacturing in a major way. MEMS consist of any combination of mechanical (levers, springs, membranes, etc.) and electrical (resistors, capacitors, inductors, etc.) components to work as sensors or actuators. The size of today's smartphones would be impossible without the use of numerous MEMS devices. Apart from accelerometers and gyroscopes, smartphones contain micro-mirrors, image sensors, autofocus actuators, pressure sensors, magnetometers, microphones, proximity sensors and many more. Another example from everyday life is the use of MEMS as accelerometers in modern automobile airbags where they sense rapid deceleration and, if the force is beyond a programmed threshold, initiate the inflation of the airbag.
Then, researchers took a further step down the size scale and have begun exploring another level of miniaturization – nanoelectromechanical systems (NEMS). NEMS are showing great promise as highly sensitive detectors of mass, displacement, charge, and energy.
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