Nanotechnology
Nanotechnology is the technique of working with structures that are only a few millionths of a millimeter in size. At this scale, materials often behave differently than they do at familiar sizes, and it is precisely this that is exploited technically.
Nanotechnology deals with very small structures. A nanometer is a millionth of a millimeter. A human hair is about 60,000 to 80,000 nanometers thick. One usually speaks of nanotechnology when components or particles are smaller than 100 nanometers. What is special about this is not just the smallness: at this scale, materials change their properties. Gold appears golden-colored as a lump, but as a tiny particle it appears red. Color, melting point, and conductivity suddenly depend on size.
Why smallness changes the rules
The most important reason is the surface. If you keep dividing a cube, the amount of material stays the same. But the total surface area grows enormously. One gram of material can have a surface area of several hundred square meters as a nanopowder. Chemical reactions take place at surfaces, so nanomaterial reacts much more readily.
That is why nanotechnology is economically interesting. Catalysts in cars need less precious metal if it is finely distributed. Batteries charge faster if ions have short distances to travel. The computer industry also depends on it: modern chips are manufactured with structure widths of just a few nanometers. Without this precision, there would be no processors for AI data centers.
However, the large surface area has a downside. What reacts more easily can also cause harm more easily. Nanoparticles can enter the body through the lungs. Their effects have not been well studied for all materials. That is why the EU has labeling requirements for nanomaterials in cosmetics and food.
Shrinking from above or building up from below
There are two basic approaches. The first is called top-down: you start with a large piece of material and selectively remove parts of it. This is how chip manufacturing works. Light with a very short wavelength exposes a layer on a silicon wafer, after which the exposed pattern is etched away. What remains are conductive paths just a few nanometers wide.
The second approach is called bottom-up: structures are allowed to form from individual molecules. Under suitable conditions, particles arrange themselves into patterns on their own. This is called self-assembly. Nature does this constantly, for example when building cell walls. Chemists use the same principle to grow nanotubes or thin layers.
Such structures cannot be seen with ordinary microscopes, because light is too coarse for that. Electron microscopes or scanning probe microscopes are used instead. The latter scan a surface with an extremely fine tip, similar to how a finger reads braille. With such tips, it is even possible to move individual atoms.
Nano in everyday products and headlines
Many applications are inconspicuous. Sunscreen often contains titanium dioxide or zinc oxide particles that block UV radiation while remaining transparent. Eyeglass lenses have nanolayers to prevent scratches and reflections. Some textiles become water-repellent because their surface is structured on a small scale like a lotus leaf.
In medicine, nanoparticles serve as delivery vehicles. The mRNA vaccines against Covid-19 package their sensitive active ingredient in tiny fat envelopes, so-called lipid nanoparticles. Without this envelope, the active ingredient would immediately break down in the body. Similar approaches are being tested in cancer therapy to deliver drugs directly to the tumor.
In business news, the term usually appears in connection with semiconductors. When talk turns to a “3-nanometer process,” it refers to the manufacturing technology of modern chips. Today, however, this number is more of a marketing name than an exact measurement. A common misconception is also the notion of floating miniature robots. Real nanotechnology almost always consists of layers, particles, and surfaces, not tiny machines.