More bytes!

A new technique that promises to increase storage capacity in computers greatly

Published: Monday 15 January 2001

while just a few years ago, 540 Megabytes was considered a huge storage for computer hard disks. Now 30-gigabyte drives are standard in most computers. However, this expansion in storage capacity is now reaching a saturation point. Data is stored in a magnetic disk as 1's and 0's. The number of bits -- an individual 1 or 0 -- that can be stored in a square area of the space on the disk is a measure of its storage capacity.

Researchers are thinking of using another method to store information that could deliver data densities that are several times higher than magnetic systems. The basic tool used is an atomic force microscope ( afm ). This instrument, invented in the early 1980s is basically a sharp needle (only a few atoms across) that is fixed to a thin cantilever, which can be moved with great precision. When such a tip is moved over a surface, the motion of the needle can detect the bumps in the surface. But soon they realised that the atomic force microscope could also be used to etch marks on a surface that are only a few molecules wide.

In principle one could make very thin marks on a surface using an afm that could then be read by the afm, but the process of scanning a surface takes a long time and these systems take about hundred times more time than conventional magnetic memories.

Now Mark Lutwyche and colleagues at ibm 's Zurich laboratory have devised a new method to speed up things. They use an array of 1,024 tips, each capable of writing and reading. The tips make indentations in a plastic film. Though they were able to store about 20 times more information in the film than conventional magnetic drives, the reading rate of the new device is still small. The bottleneck is the software that interfaces the atomic tip with the computer. Once the software limitations are taken care of, they will have memories that can store many times more data than magnetic drives ( Applied Physics Letters , Vol 77, p3299).

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