Nanotechnology Frequently Asked Questions

What is nanotechnology?
Major technology shifts don't happen overnight; and rarely are they the result of a single breakthrough discovery. Nowhere is this more true than for the vast set of capabilities that we have come to simply call nanotechnology.
Nanotechnology is not an industry; nor is it a single technology or a single field of research. What we call nanotechnology consists of sets of enabling technologies applicable to many traditional industries (therefore it is more appropriate to speak of nanotechnologies in the plural).
What exactly is nanotechnology? We answer this question in depth in our Introduction to Nanotechnology section.
How big is a nanometer?
A nanometer is one billionth of a meter. The prefix nano means 'one billionth', or 10-9, in the international system for units of weights and measures. The abbreviation for nanometer is nm. The term nanos comes from the Greek word for dwarf.
Also check our metric prefix table and The Scale of Things to see where nano fits in.
What are zero-, one-, two-, and three-dimensional nanomaterials?
Nanomaterials are primarily categorized based on the dimensional characteristics they display. These dimensions are classified as zero-dimensional (0D), one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) nanomaterials, all of which fall within the nanoscale range.
nanoscale dimensions
Classification of nanoscale dimensions. (© Nanowerk)
Quantum dots and small nanoparticles are often referred to as "zero-dimensional" (0D) structures, despite having three physical dimensions. This might sound confusing at first, but it’s because we’re talking about their quantum mechanical properties rather than their geometric shape. Let's unpack this a bit:
Quantum Confinement in All Three Dimensions: In quantum dots or small nanoparticles, electrons experience quantum confinement in all three dimensions, much like being restricted in an extremely tiny room. This confinement is effective when the size of the particle is comparable to or smaller than what is called the “exciton Bohr radius” of the material, which is typically a few nanometers This confinement limits the electrons to specific energy levels, their “discret energy levels.” Think of it as a game of musical chairs at the quantum scale: the electrons, like players in the game, can only occupy certain 'seats' or energy states.
The number of these available 'seats' is determined by several factors:
  • The size of the particle: Smaller dots mean tighter confinement and more distinct energy levels.
  • Material properties: Different materials have different inherent energy states, influencing how many discrete levels are available.
  • Quantum mechanics: This dictates the fundamental rules for how energy levels are arranged in such confined spaces.
  • As a result of these combined factors, electrons in quantum dots have a limited set of energy levels they can occupy, akin to having a set number of chairs in the room. This is a stark contrast to larger, bulk materials where electrons have a more continuous range of energy levels available.
    Exciton Bohr Radius: The exciton Bohr radius is a key factor in determining the size limit. It is like a measuring stick that tells us how small we need to make our nanoparticle to see its cool quantum effects. It varies between materials but is generally in the range of a few nanometers. When the size of the nanoparticle is smaller than or similar to this radius, quantum confinement effects are significant, and the particle behaves as a 0D system.
    Size and Quantum Effects: The size of quantum dots is typically 2-10 nanometers. At this scale, the quirky rules of quantum mechanics start to dominate, making these particles behave very differently from larger pieces of the same material.
    Comparison with Higher Dimensions: In our room analogy above, think of 1D and 2D materials, like nanowires and thin films, as narrow hallways and wide floors. Electrons can move freely along these hallways or floors but can’t jump out of them. This partial freedom leads to different behaviors compared to the completely confined quantum dots or nanoparticles.
    Transition to 3D Behavior: As the size of the nanoparticle gets bigger, beyond the exciton Bohr radius, it starts behaving more like a regular, bulk material. The electrons begin to move more freely, akin to how water starts to flow when a dam is opened, leading to a more continuous range of energy levels. This marks the transition towards 3D behavior.
    Material-Dependent Threshold: The exact size at which this transition occurs depends on the material of the nanoparticle. Different materials have different exciton Bohr radii and therefore different thresholds for the transition from quantum-confined (0D) behavior to bulk-like (3D) behavior.
    Gradual Transition: It's important to note that the transition from 0D to 3D behavior is not abrupt but gradual. As the nanoparticle grows, its energy levels slowly spread out, moving from distinct steps on a ladder to more of a ramp. Accordingly, a material's physical properties change as the energy levels evolve from discrete to continuous.
    To sum up the dimensionality issue in nanomaterials, each class—zero-dimensional (0D), one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D)—displays unique properties due to the extent of quantum confinement. In 0D materials, electrons are confined in all dimensions, leading to atom-like behaviors. In 1D materials, such as nanowires, confinement occurs in two dimensions, allowing electron movement in one direction. 2D materials, like graphene, confine electrons in a plane, resulting in unique electronic and physical properties. Finally, 3D materials, where quantum effects diminish, resemble bulk materials but with enhanced surface properties due to their nanoscale dimensions. Each dimensionality offers distinct physical, chemical, and electronic characteristics, making them suitable for various applications in science and technology. The transition from 0D to 3D is not abrupt but gradual, with properties evolving as the dimensionality increases, leading to a diverse spectrum of behaviors and potential applications in the realm of nanotechnology.
    In zero-dimensional (0D) nanomaterials, all dimensions are confined to the nanoscale, typically not exceeding 100 nm. This category primarily includes quantum dots and nanoparticles, where electrons are quantum confined in all three spatial dimensions, leading to unique optical and electronic properties.
    One-dimensional (1D) nanomaterials, such as nanotubes, nanorods, and nanowires, have one dimension that extends beyond the nanoscale, allowing electron movement along their length. This unique structure endows them with distinct mechanical, electrical, and thermal properties.
    Two-dimensional (2D) nanomaterials are characterized by having two dimensions beyond the nanoscale. These materials, including graphene, nanofilms, and nanocoatings, are essentially ultra-thin layers where electrons are free to move along the plane but are confined in the perpendicular direction. This results in exceptional surface area, electrical conductivity, and strength.
    Three-dimensional (3D) nanomaterials are those in which none of the dimensions are confined to the nanoscale. This diverse class includes bulk powders, dispersions of nanoparticles, aggregates of nanowires and nanotubes, and layered structures. In these materials, the unique properties of nanoparticles are combined with bulk material behaviors, leading to a wide range of applications and functionalities.
    How does nanotechnology work?
    Nanotechnology is the understanding and control of matter at the nanometer scale, where unique phenomena enable novel applications. Encompassing nanoscale science, engineering, and technology, nanotechnology involves imaging, measuring, modeling, and manipulating matter at this length scale.
    Nanotechnologies involve the design, characterization, production, and application of nanoscale structures, devices, and systems that produces structures, devices, and systems with at least one novel/superior characteristic or property.
    What is so special about nanotechnology?
    In a nutshell: the mechanical rules that govern the nanoworld are quite different from our everyday, macroworld experience. This allows the fabrication of novel materials and applications that otherwise would not be possible. For more details, read our section on what is so special about nanotech and why it is an issue now.
    What are nanomaterials?
    Much of nanoscience and many nanotechnologies is concerned with producing new or enhanced materials. Nanomaterials can be constructed by top down techniques, producing very small structures from larger pieces of material, for example by etching to create circuits on the surface of a silicon microchip. They may also be constructed by bottom up techniques, atom by atom or molecule by molecule. One way of doing this is self-assembly, in which the atoms or molecules arrange themselves into a structure due to their natural properties. Crystals grown for the semiconductor industry provide an example of self assembly, as does chemical synthesis of large molecules.
    If 50% or more of the constituent particles of a material in the number size distribution have one or more external dimensions in the size range 1 nm to 100 nm, then the material is a nanomaterial. It should be noted that a fraction of 50% with one or more external dimensions between 1 nm and 100 nm in a number size distribution is always less than 50% in any other commonly-used size distribution metric, such as surface area, volume, mass or scattered light intensity. In fact it can be a tiny fraction of the total mass of the material.
    Even if a product contains nanomaterials, or when it releases nanomaterials during use or ageing, the product itself is not a nanomaterial, unless it is a particulate material itself that meets the criteria of particle size and fraction.
    The volume specific surface area (VSSA) can be used under specific conditions to indicate that a material is a nanomaterial. VSSA is equal to the sum of the surface areas of all particles divided by the sum of the volumes of all particles. VSSA > 60 m2/cm3 is likely to be a reliable indicator that a material is a nanomaterial unless the particles are porous or have rough surfaces, but many nanomaterials (according to the principal size-based criterion) will have a VSSA of less than 60 m2/cm3. The VSSA > 60 m2/cm3 criterion can therefore only be used to show that a material is a nanomaterial, not vice versa. The VSSA of a sample can be calculated if the particle size distribution and the particle shape(s) are known in detail. The reverse (calculating the size distribution from the VSSA value) is unfeasible.
    Read our extensive section on nanomaterials for a list of nanomaterials being developed today: films and surfaces; single- and few-layer materials like graphene; nanotubes; nanowires; fullerenes; quantum dots and all kinds of nanoparticles.
    What is graphene?
    We have a detailed article for you on what graphene is, complete with an introductory video.
    What are synthetic nanoparticles?
    We have a detailed article for you on synthetic nanoparticles.
    What are nanoclusters?
    In addition to nanoparticles, you will also come across the term nanocluster quite often. These are small agglomerates of atoms and molecules, consisting of a few to some thousands of units and have diameters mostly in the single nanometer scale. The name nanoparticle is often used when speaking of bigger clusters with diameters from several nanometers to several hundreds of nanometers, but the distinction between a cluster and a nanoparticle is not well-defined.
    How are nanoparticles made?
    We have a detailed article for you on how nanoparticles are made.
    Where is nanotechnology used today – Can I buy nanotechnology products?
    Yes! Nanotechnology is becoming ubiquitous in our daily lives and has found its way into many commercial products, just to name a few: strong, lightweight materials for cars and planes; filters and membranes; targeted drug delivery for safer and more effective cancer treatments; computer processors and data storage; self-cleaning surfaces; more efficient solar cells; materials for skin, bone, and nerve cells regeneration.
    Consumers come into contact with a variety of products in which nanomaterials have been processed. Nanomaterials are used in food packaging, textiles, kitchen devices, varnishes and paints. They are also used in products for surface sealing and cleaning as well as in polishing agents. Nanomaterials are also used in cosmetics. Titanium dioxide and zinc oxide are used as UV filters in sun creams, for example; nanosilver is used as an antimicrobial agent in textiles and nanoclay has various applications in the food packaging sector.
    For instance, the average home is already filled with products enhanced or reliant upon nanotechnology. For further reading, we have compiled numerous articles on nanotechnology applications that are on the market or in development today.
    Who is developing nanotechnology?
    Researchers in thousands of university, industry and government research laboratories around the world. Our Nanotechnology Company & Research Laboratories Directory currently lists almost 4000 entries.
    Where is nanotechnology being developed?
    In thousands of university, industry and government research laboratories around the world. Our Nanotechnology Company & Research Laboratories Directory currently lists almost 4000 entries.
    Rather than standing on the shoulders of a few intellectual giants, nanotechnologies get created by tens of thousands of researchers and scientists working on minute and sometimes arcane aspects of their fields of expertise in a multitude of areas; they come from different science backgrounds; live in different parts of the world; work for different organizations (government labs, industry labs, universities, private research facilities) and follow their own set of rules – get papers reviewed and published; achieve scientific recognition from their peers; struggle to get funding for new ideas; look to make that breakthrough discovery that leads to the ultimate resumé item, a nobel prize; get pushed by their funders to secure patent rights and commercialize new discoveries.
    These three books provide a collection of essays about hundreds of researchers involved in all facets of nanotechnologies: Nano-Society: Pushing the Boundaries of Technology,
    Nanotechnology: The Future is Tiny, and
    Nanoengineering: The Skills and Tools Making Technology Invisible.
    Where will nanotechnology take us?
    When we asked the question 'where nanotechnology will take us', we need to differentiate between two types of nanotechnologies: One is happening right now and the other is the stuff of science fiction and way-out technology scenarios.
    What we are dealing with today is evolutionary nanotechnology. The goal of evolutionary nanotechnology is to improve existing processes, materials and applications by scaling down into the nano realm and ultimately fully exploit the unique quantum and surface phenomena that matter exhibits at the nanoscale. This trend is driven by companies' ongoing quest to improve existing products by creating smaller components and better performance materials, all at a lower cost.
    By contrast, truly revolutionary nanotechnology envisages a bottom-up approach where functional devices and entire fabrication systems are built atom by atom (just to be clear, here we are not just talking self-assembly and chemical synthesis of nanomaterials but functional machinery). Unless you resort to science fiction scenarios it will be impossible to make even educated guesses as to what that future might bring.
    We have posted a series of scenarios about "Nano Tomorrows" that in detail a range of plausible, challenging events – from pandemics to climate crises to international conflicts – to see how they might affect the development of advanced nanotechnology over the next 15 years.
    Are there any specific health or other risks from nanoproducts?
    Unfortunately, there is no simple 'yes' or 'no' answer to this question. There are lots of different aspects to consider and we have tried to cover them all in our Nanotechnology – the Risk Factors article.
    Also take a look at our article on nanoparticles, free radicals and oxidative stress with an overview about what free radicals are, how they originate, why organisms need them, how they are neutralized, and what we know about the connection between nanoparticles and free radical production.
    How to study nanotechnology? Where can I find a college or university that offers nanotechnology programs and degrees?
    Which universities offer nanotechnology courses? Where can you get a degree in nanotechnology and related fields? Easy. We have compiled a database with about 300 bachelor, master, Ph.D. and other certification nanotechnology and nanoscience degree programs from around the world.
    Where can I find companies that make nanomaterials or are involved in nanotechnologies?
    Our extensive nanotechnology company database list raw material producers, companies involved in biomedicine and life sciences, all kinds of nano-related products, applications and instruments; as well as services and intermediaries.
    What countries are active in nanotechnology?
    Our Global Nanotechnology Markets section lists companies, research laboratories and degree programs by country as well as individual U.S. states.
    Where can I find a list of nanotechnology-related events, seminars and conferences?
    What professional journals and magazines cover nanotechnology-related issues?
    We have compiled a global nanotech publications directory that lists publications dedicated wholly or primarily to nanoscience and nanotechnology – academic journals, magazines, newsletter, free e-books and book series.
    Show me some cool nanotechnology images
    Happy to. Some of the many nanotechnology images we have compiled for you will blow your mind!