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Sci Tech
New science of small things
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The demonstration by IBM earlier this week of the highest storage density ever achieved _ one trillion bits per square inch — underlines why nanotechnology may become the most exciting technology breakthrough of the new millennium. Anand Par thasarathy examines what it means for computer storage.
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The millipede concept (top) and the chip (bottom) showing wiring for 1024 tips in a 3 mm x 3 mm square.
Note to Arundhati Roy: Be warned; there is now a new `God of small things'. And the name is nanotechnology.
WITHIN THIS decade we will have computer hard disks of 100 gigabytes. Glass windows can be coated with a film that will repel dust and make it self-cleaning. A sunscreen lotion will automatically cut off the sun's ultra violet rays. That jacket you are wearing, will be cool in summer and in winter it will switch roles to keep you warm. It will also say `no' to stains of all kinds. And if you are a soldier it will change colours to match the terrain, making the wearer a human chameleon. Ready-to-use bandages will automatically cure your wound.
Almost all these ideas are way beyond the drawing board — many of them are ready to be launched as commercial, albeit currently pricey, products.
And all of them without exception exploit the new science of the very small: nanotechnology...the science of building devices at the level of molecules and atoms, when individual elements are one billionth of a metre long (one nanometre is one billionth of a meter or 10{+-}{+9}).
In this miniature `maidan', full atoms of hydrogen and carbon will be the size of a cricket ball. Now think what you can do when your building blocks are so small: a row of titanium elements will form an extremely hard gear wheel; a string of carbon particles will form a very strong wire.
And if you can make some titanium dioxide powder at this level and add it to body lotion, it will protect your skin from the harsh rays of the sun, without being seen... which according to a recent article by David M. Ewalt in Information Week is exactly what one company has done.
Perhaps more than anywhere else, the promise of nanotechnology is causing excitement in the computer chip and memory business — for very good reasons: the perceived end of the road for Moore's Law. This was an industry `mantra' coined by Intel co-founder Dr Gordon Moore, who predicted that technology that went into integrated circuits roughly doubled in power every 12-18 months. That is why the latest Pentium 4 chip clocking 2.4 gigahertz, is about 25,000 times faster and packs 25,000 as many transistors on board as the first ever microchip, the Intel 4004 of 1971.
That is why that state-of-the-art PC you bought with your hard earned savings is obsolete even as you devoutly break that coconut to inaugurate it: they have already prototyped one that works twice that fast. But for how long will this happy (or unhappy, depending on your viewpoint) state continue? Physicists, the spoilsports, say: another 10 years at the most: after that human ingenuity may dream up a bigger, better, microchip on that slab of silicon, but the laws of physics will not permit all those ones and zeroes to run along its micro tracks.
That is why nanotechnology is being perceived as the great Rescue Act of the mid 21st C. The ability to fashion electronic circuits — entire computers — with atom-length nanowires or nanotubes, made from carbon rather than silicon, may allow computer hardware to progress beyond physical barriers of Moore's Law. Like the Kalki Avatar, the Moore's Law may return in another form, to rescue silicon from oblivion.
Super-dense storage
Only two days ago, some of the most exciting news in nanotech research came from the Zurich ( Switzerland) research labs of IBM. The inaugural (June 2002) issue of the ``IEEE Transactions on Nanotechnology'' carries a report from the IBM team that it has succeeded in achieving a storage density of one trillion bits per square inch — that is 25 times as dense as today's hard disks. In lay person's terms, this means putting the content of 300 CDs, each holding 700 MB of data, on a surface as small as a matchbox. How did they do this? Instead of using conventional magnetic or electronic methods of storage, IBM achieved these densities by using thousands of sharp tips, to punch nano-sized indentations representing individual bits on a thin plastic film.
To do this the IBM team created a two-dimensional array of v-shaped silicon `cantilevers' that are half a micron thick and 70 microns long. (One micron is one micrometre or one millionth of a metre). At the end of each cantilever is a downward pointing tip, less than 2 microns long. The chip realized, christened Millipede, consists of an array, 3 mm by 3 mm, equal to 32 x 32 cantilevers — that is 1024 separate elements created by micromachining the silicon surface. Accompanying illustration shows the schematic of the array and the enlarged photograph of the actual electrical wiring for 1024 bits.
A driver circuit `addresses' each tip individually for parallel and multiplexed operation. The beauty of this system is that it is completely reversible. The prototype achieved a potential capacity of half a billion bytes in the 3mm by 3mm array. The team is already working on a four-fold increase in density in a 7mm by 7mm array.
Students of technology history will be struck by the parallels of this nano array with that classic storage medium — the Hollerith punched card. Then as now, holes made by a tiny punch represented the code for data stored. The Reuters correspondent, who reported this news on Tuesday, saw this historic parallel: He titled his story: Back to the Future with nanotech `punched card'. But there the similarity ends — a nano `Millipede' unveiled this week holds 3 billion bits of information in the size of the original Hollerith punched hole.
As the French say, `plus ca change, plus c'est la meme chose!' — the more things change, the more they are the same.
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