When you hear the word "nanotechnology", what comes to mind? If you're like many, the answer is something along the lines of, "well, I know it's really small." Those with a little more familiarity may describe little robots that swim through your bloodstream and clean out your arteries or a swarm of self-replicating nanobots that threaten our existence. These popular ideas come mostly from science-fiction sources such as the Michael Crichton blockbuster Prey. And while they contain a grain of truth, nanotechnology is both much more exotic and much more down-to-earth.
The prefix "nano-" comes from the Greek word for dwarf. In science nano- has a specific meaning. When nano- precedes a word, it means a billionth which is expressed in scientific notation as 10-9. So a nanometer (nm) is a billionth of a meter or 0.000000001 m. That's pretty small! So small that we cannot see a nanometer-scale object without a very powerful microscope.
This graphic from the US Department of Energy helps put the nanoscale into perspective.
Put the nano- together with technology and what we have is technology at the nanometer length scale. Here's a working definition:
Nanotechnology--Science and engineering of matter of sizes between about 1-100 nm to exploit the novel phenomena that emerge or are enhanced at this size scale.
Let's break that down. Science and engineering: generally speaking, scientists study natural phenomena and engineers apply knowledge of natural phenomena. (In fact, there is a lot of crossover between what scientists do and what engineers do.) Sizes between about 1-100 nm: in other words, smaller than particles but larger than atoms and most molecules. Novel phenomena: matter in the nanoscale size range can behave very differently from the same matter at a smaller or larger scale. To sum up, not only does the object need to be small but it has to have some special property because it is small.
An example of nanotechnology
It might surprise you to know that you probably already use products of nanotechnology. Let's analyze a common household product to see the nanotechnology within. The example chosen is sunscreen. Some sunscreens use minerals such as titanium dioxide or zinc oxide to reflect harmful ultraviolet rays and protect your skin while you're in the sun. When the mineral particles are microscopic (a thousand times bigger than nano) they scatter visible light as well, making them appear chalky and white. But when we make the particles at the nanoscale they still block ultraviolet light but no longer scatter visible light. Thus, they are transparent and do not leave a chalky white film. The size of the particle influences how it interacts with light. When it's small, it doesn't scatter visible light; when it's larger, it does. Therefore the novel phenomenon exhibited by nano-sized sunscreen minerals is their transparency to visible light.
Nanotechnology is a broad and diverse area of science, engineering and product development. While it may someday enable exotic technologies now in the realm of science fiction, nanotechnology is already here today.