What is Nanotechnology?
The prefix nano- means "a billionth of a..." or one part in 1,000,000,000. In the context of nanotechnology, nano- refers to a billionth of a meter - a "nanometer." A DNA molecule, the double helix, has a diameter of about 2.5 nanometers. The spacing between atoms in a crystal is about 0.2 nanometers. The diameter of a human hair is about 80,000 nanometers. The best conventional optical microscope can only resolve objects larger than about 500 nm, on the order of the wavelength of visible light.
Nanotechnology is the vast frontier between what we know very well - for example, the electronic structure of atoms and small molecules - and what we know well enough, as in the average behavior of microscale materials and submicron devices such as a transistor in a silicon integrated circuit. In this seemingly narrow, but incredibly rich intermediate zone, complex and surprising behavior is commonplace. Nanomaterials with characteristic dimensions in the range of 1-100 nanometers - a size range encompassing the spatial extent of a conduction electron in a crystal and the wavelength of a lattice vibration that carries sound and heat (a "phonon"), and somewhat smaller than the wavelength of a visible particle of light (a "photon") - show properties that are strongly size dependent. Two nanoscale particles with identical chemical compositions, but different in size or shape, will have different electronic, optical, chemical, and thermal properties - they will be essentially distinct materials. Even two nanoparticles of identical size and shape can have much different properties if the atoms in one are arranged with perfect order, while the other contains a single atom that is out of position. Nanomaterials often interact with each other to "self-organize" in a manner akin to crystal growth and the development of simple biological structures. Learning to direct these self-organizing tendencies is the key to the emerging field of nanomanufacturing. Designing nanosystems that can accommodate the occasional defects introduced during nanomaterials synthesis and assembly represents a formidable but important intellectual challenge.
Nanotechnology impacts almost everyone, every day. From the nanoscale memory devices in your MP3 player to the quantum dot emitters of green light in the light emitting diodes (LEDs) in a green traffic light, nanotechnology is already taken for granted as part of everyday 21st century life. "Nano-" as a prefix is used to sell everything from sports equipment to stain resistant and odor suppressing clothing; in some of these applications, the nano- prefix is warranted; in others, the nano content is dubious. Nevertheless, the impact of nanotechnologies will continue to grow, benefiting health, security, environmental protection, food safety, and energy conservation.