What is Nanotechnology?
Nanotechnology is often defined as an engineered structure which has at least one dimension which is less than 100 nanometres (100nm) in length. This sort of length is very short (less than 100 billionths of a metre) which is 1000 times smaller than the typical house dust mite and 100000 times smaller than a typical red ant. There are two different approaches to the fabrication of nanoscale structures. The first is a top-down approach where a large piece of material is reduced down to a smaller piece of material using chemicals or heat to attack the surface of the material. The second approach is a bottom up approach where the nanostructure is built up from its constituent atoms which is known as self assembly.
It is important to understand fully how a nanomaterial or structure behaves to make sure that it doesn’t produce any undesired effects such as unexpected failure in serviceand to make sure it does the job we want it to do. This is often done by comparing images of the nanomaterial before and after exposure to a certain set of conditions (e.g. changes in pH, mechanical loading and changes in temperature). But how do you look at something that is smaller than the resolution of a typical optical microscope? There are a number of techniques available to the scientist including atomic force microscopy (AFM), scanning tunnelling microscopy (STM) and Scanning Electron microscopy (SEM). Although it is beyond the scope of this article to describe these techniques in detail, briefly AFM and STM have sufficiently high resolution to image atoms allowing a measure of surface roughness and SEM allows imaging and measurement of particle sizes and aggregation (clumping of particles).
Examples of Nanotechnology
Nanotechnology is finding many uses in a wide variety of fields including medicine and electronics. Examples of nanotechnology in these areas include microprocessor chips (45nm in length) and gold nanoparticles for targeted cancer treatment. The gold nanoparticles are modified with a molecule that responds only to molecules on the cell membranes of cancer cells. When the gold nanoparticles are injected near to the site of the cancer they join up with the molecules on the cell membrane allowing the particles to enter the cell. It is then possible to cook’ the cancer cells by selectively heating the area using microwave. The microwaves cause the gold nanoparticles to become hot which heats the water in the cancer cells and causes the cancer cell to burst.