Introduction to Nanoscale Technology
Things are different at different size scales. A flea can jump many times its height; an elephant cannot jump at all. In general, smaller things move faster, weigh less, and are often more powerful; this is called “scaling laws.” Tiny droplets of oil may “pop” with enough force to kill bacteria. Sometimes, very small things behave differently because of physics quirks. Tiny particles of gold may change color to red or even blue. Harnessing these physics quirks, sometimes called “quantum effects,” is the basis for some of the interest in nanoscale technologies.
A small chunk of material-less than 100 nanometers on a side-is called a nanoparticle. A nanoparticle is less precise than a molecule: it is defined by size rather than by chemical composition. Almost any material can be made into nanoparticles, including carbon, metals, oil, and silicon. Nanoparticles often behave differently than the larger versions of the material, sometimes from quantum effects and sometimes from scaling laws.
The wires and switches inside computer chips have been getting steadily smaller for decades. They have recently crossed the 100-nanometer threshold, sufficient to be considered nanotechnology by the NNI definition. As they continue to shrink, quantum effects will become increasingly important, and current designs will stop working. There are several nanoscale technologies that could take over. One is molecular electronics: the use of single molecules (or sometimes, small clusters of molecules) to build wires and switches. Another is quantum dots: instead of letting electrons flow through wires, the electrons are tethered in place and only shift back and forth. This shift causes nearby electrons to shift also, which is useful for signaling and computation.
High-speed signaling between computers is done with light. Handling this light, and perhaps even using it inside computers, is the domain of photonics. Photonics overlaps with nanoscale technology because some new photonics materials use nanoscale structures. With light, quantum effects can happen even at relatively large sizes.
Many fields of medicine are starting to benefit from nanoscale technology. The ability to make complicated molecules, and to join non-molecular nanoparticles with molecules, allows the creation of new kinds of medicines. Better sensors allow faster, cheaper, and more accurate diagnosis. Better materials lead to improved surgical implants.
Sensors are devices that report on some aspect of their environment, such as chemicals, sound, light, and mechanical forces. They are useful in medicine, environmental monitoring, and automation. Nanoscale technology can improve many different kinds of sensors, making them cheaper to manufacture and operate, smaller, and more sensitive.