Writ Large on the Nano-Scale

Nanotechnology – the science of the incredibly small – may be the future of electronics, biotechnology and healthcare, but there are still many hurdles to overcome before it can deliver on its promises. One of the most important problems facing nanotechnology is how to manipulate things less than one millionth of a metre in size!

Nano-art? These drawings are only 150 millionths of a metre across. Image: Wikimedia Commons

Now, American researchers have developed the “NanoPen” – a device that allows them to draw patterns of nanoparticles in seconds. Although other researchers have worked out how to create nano-scale patterns their methods take a long time and require high temperatures and light intensities to work. The new technique works quickly, and at low light intensities, making it much easier to sketch a nano-masterpiece.

NanoPen works by using a pattern of light projected onto a “photoconductive” surface. Where light hits the surface it makes it more conductive to an electrical current. The change in conductivity alters the properties of the surface, creating tiny forces which pull the nanoparticles into the light and anchor them in place, creating the pattern.

The researchers believe the technique could be used to draw miniature electronic circuits, build nano-structures, or create DNA microarrays – a vital tool for the biological sciences – quickly and cheaply.

Of course, to test the technique the researchers used gold nanoparticles to draw the logos of their funder (the NIH) and the university where they work (CAL, or the University of California), as you can see above.

Picking up good vibrations

How do you weigh the basic building block of matter, the atom? You can make an educated guess by weighing a whole clump of identical atoms, use A-Level chemistry to estimate how many atoms you should have in your clump, and divide one by the other to give you your answer. This imprecise method wasn’t good enough for one group of European researchers, however. Instead they’ve came up with a clever way of weighing one atom at a time.

To do so they use carbon nanotubes – sheets of carbon rolled into tubes thousands of times narrower than a human hair. Carbon nanotubes vibrate, like a guitar string, at a characteristic frequency. The frequency changes if the weight of the nanotube changes – for example if another atom is stuck to it. By running an electrical current along the nanotubes the researchers could measure the vibrations of the nanotube by looking at changes to the electrical current. From there they could compare the vibrations of the nanotube with and without the atom attached, and work out its weight. Simple, yes?

The researchers believe the work will allow molecular biologists and chemists to follow, in incredible detail, how molecules (which are made up of many different atoms) change as they interact in real-time. This will tell us much more about how our cells function at the smallest scale: something we currently know very little about.

Atoms don't really look like this, but it'll do...