Like quantum, artificial intelligence and energy, nanotechnology is an oft-used science buzz word that makes headlines.
But what is nanotechnology, really?
The “technology” bit will make sense later. Understand where “nano” comes from by looking at a ruler.
Size matters
A typical ruler is about 30 centimetres long. Usually, the centimetres on a ruler are subdivided into millimetres. One millimetre – about the thickness of a ball-point pen line – is one-thousandth of a metre with the prefix “milli-”. So, one millimetre is 0.001 metres.
Now divide that millimetre up into a thousand units. That makes a millionth of a metre. In scientific convention, the prefix which means a millionth of something is “micro-”, so a millionth of a metre is a micrometre, which is sometimes called a “micron.” Things on the micrometre scale often aren’t visible to the human eye and require a microscope to be analysed properly.
A human hair, for example, is between 50 and 100 micrometres thick. Human red blood cells are only about 7 to 8 microns wide.
Divide a micrometre up into a thousand units yet again, and we get to the nanoscale.
A nanometre, therefore, is one-billionth of a metre, or 0.000000001 metres.
Things on the nanoscale are so small that normal optical microscopes (microscopes that use visible light) can’t be used to study them. Instead, electron microscopes are used because electrons have wavelengths around a tenth of a nanometre.
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The nanometre scale is the scale of molecules.
DNA molecules are about two nanometres wide. Most proteins are about 10 nanometres wide, and a typical virus is around 100 nanometres long. It’s not too much further that we get to the size of individual atoms which are typically between 0.1 and 0.5 nanometres in diameter.
What’s so special about nanomaterials?
Nanoscale objects, also called nanostructures, are so small that materials have completely different chemical and physical properties.
University of Newcastle professor Thomas Nann, Head of School of Information and Physical Sciences, gives an example.
The one thing that stands out about the element gold is its colour. But Nann explains: “If you make gold into very small nanoparticles, it changes colour. Rather than reflecting light and having its golden, shiny colour, gold becomes red. This is used in pregnancy tests. The red dye you’re looking at is actually made of gold nanoparticles.”
But that’s not all. Nanostructures don’t just change the colour of materials.
Other characteristics which change at the nano level include magnetism and electronic properties.
Dr Renee Goreham, also from the University of Newcastle, notes that a team of researchers she works with make quantum dots – a type of nanomaterial – based on indium phosphate.
“I don’t even know what that would look like at a bulk scale, but it wouldn’t be very interesting,” Goreham says. “We get the material down to about five nanometres, and we create a fluorescent nanoparticle which wouldn’t usually fluoresce.”
Nanoparticles behave “completely differently to what we would see with the naked eye,” Goreham says.
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Nanoparticles sit between the macroscopic, classical world we experience every day, and the outright strangeness of quantum mechanics at the size of atoms and particles.
“Nanotechnology is the application of these properties,” Nann adds.
Nano this is done in vain
Ten to twenty years ago, nanotechnology was all the rage. There was talk of how nanorobots were going to be swimming in our bloodstreams, nanomaterials were going to give us holograms, and all sorts of flashy science fiction opportunities.
Not all of this has eventuated (yet). But nanotechnology certainly has made a huge difference on our lives already. Nann explains that nanotechnology is “actually all around us, without us even noticing.”
For example, titania nanoparticles are used in sunscreen to absorb UV light.
There are also nano patches which use nanometre-sized needles, usually made of silicon, to administer specific doses of medicine. Nanoparticles are also used in other medical applications like in contrast agents to aid in MRIs.
Research into nanotechnology is ongoing, and exciting applications continue to come out of the science of this liminal space between the quantum world and our everyday macroscopic experience.
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