The smaller the better?
- What is Nanotechnology?

The Victorians compared the human brain to their technology - it was a machine with cogs and pulleys which processed facts and came up with thoughts. It was a reasonable analogy and it no doubt served them well - but we tend to look back and laugh at it now. We say the brain is more like a computer, electronically processing information and coming up with new ideas and opinions. We even know that electrical impulses run along the neuron pathways in the brain so we must be right.

But aren't we doing the same as the Victorians? We're just thinking of the brain in terms of current technology. It may seem wonderfully modern but so did theirs at the time and who's to say our analogy is any better than theirs? Perhaps both are wrong? Perhaps there's another technology bubbling under which might lead to a new analogy that our grandchildren will use - as they laugh at our old fashioned ideas!

What that technology might be is difficult to predict but nanotechnology seems to be the front-runner. It's based on the concept of very small - and in nanotechnology 'very small' means at the molecular level!

A nanometre is one millionth of a millimetre. It's quite impossible to imagine so don't try. But it is real. The computer industry has already entered the 'nanoworld' and the smallest components within a chip are about 100 nanometres in size - and getting smaller. But this isn't the reason why nanotechnology is causing such interest.

Top down or bottom up
All previous miniaturisations have resulted from starting with something large and gradually working downwards in size. Do you remember valves? They used metal heaters in glass tubes to handle electrons. Then came the transistor. Then the microchip.

These developments have followed Moore's Law which states that computer performance will double every eighteen months. They've been going on for the past three or four decades and they result from improvements in technology rather than new thinking.

Nanotechnology, on the other hand, is a radical re-think of the way things are done. With nanotechnology you start at the bottom and work up - you start with molecules and build them up to useable devices. This is actually how nature works. The molecules of basic chemical substances click together to form proteins, enzymes, DNA and ultimately, cells, plants and animals - including us!

Meeting in an invisible world
Chemists and biochemists are working towards the creation of molecular assemblies of about the same size the chip makers are reaching using their 'top down' methods. They are literally going to meet in the middle of a strange nanoworld that's too small to see.

It's not science fiction. It's really happening. Nanotechnology is just moving from exploration to application and the first products are beginning to appear. One is probably in your possession already. It's a new kind of impact sensor for airbags in cars and it actually came out in 1995. It's not only smaller and more efficient than the sensors previously available but 100 times cheaper! However, this is a 'top down' product - it was built using conventional technology, but very very small.

Now there is at least one product available which has been engineered from the bottom up. That is to say, it's been built by manipulating molecules, using such equipment as "laser tweezers" and the "atomic force microscope". These devices allow researchers to individually position molecules in order to research how they respond to changed conditions. The first product is a self-cleaning window!

It doesn't sound that exciting but it's been created at a molecular level and this is how it works. A new molecule in the glass oxidises common kinds of dirt so they wash away without sticking. Just as plants use the power of light to convert minerals into sugars so this glass converts dirt particles into soluble molecules that just wash away. There's a second part of the process. The glass is coated with a molecule which makes water spread rather than form beads. The result is no dirty dots where the beads of water were, in fact no dirt at all because it just washed away! It sounds simple but it wasn't possible before molecular design on the nanometre scale.

Self cleaning glass is two-dimensional engineering - the surface of the glass is a flat area and it's easier to manipulate molecules in 2D. Working in three dimensions is harder but it will come and when it does we can probably expect equipment to shrink considerably. Imagine a mobile phone built into a shirt button - or a tooth! Computers have spent the past 25 years becoming ubiquitous in our lives, perhaps they are now about to become invisible!

Targeted medicines
Perhaps the most exciting opportunities are in medicine. Even though most drugs combat a particular cell type, the fact is that using them is like immersing a computer in a bath to clean one chip. Using a scalpel to fix a medical problem is the equivalent of using an axe to fix a computer.

There are two immediately obvious roles for nanotechnology devices. One is in pain relief and the other for diabetes. Imagine a pain-relief chip inserted with a replacement hip which would cover a patient's needs for months. Or imagine a chip that can sense insulin levels in the blood and dispense the correct amount automatically. These are just the first ideas - the potential for localised, targeted treatment is probably unlimited.

'Grey Goo'
There is, of course, a potential downside. A few years ago nanotechnologist called Dexler suggested that miniature robots called "assemblers" could be made that would be able to rearrange atoms. Bill Joy of Sun Microsystems then wrote an article in Wired magazine in which he speculated that if someone made one that fed on organic matter and was indigestible to animals it would instantly be at the top of the food chain. If the miniature robot was also a "replicator" - i.e. it could make copies of itself - the result would be to gradually turn the entire world into a grey goo.

Fortunately, this seems an unlikely scenario - but then, you never know.