Other Storage Technologies

This stuff is getting close to rocket science, but if the problems are resolved, they could change the face of storage.

The Millipede project - Punched cards are coming back!

The storage trend is to pack more and more data into a smaller space, or improve the aerial density as it is known. It will be necessary to get down to nanometer dimensions to improve on aerial densities provided by magnetic disks. One way to do this is to use a very sharp tip to poke a hole in some sort of storage medium. This sounds a bit primitive, not to say optimistic, but IBM has produced nanometer scale punched storage cards called millipede.

Millipede is based on the nanometer sharp tips used in an atomic force microscope (AFM). The prototype millipede used 25 cantilever tips is a 5x5 array. This was scaled up to a 32x32 array which will read and write a 1kb (1024) block in a 3mm square.
Millipede uses a polymer storage substrate and basically writes data by heating the substrate. If the AFM tip is 'hot' then it makes an indent in the substrate, if the tip is 'cold' the substrate remains smooth so producing the traditional data pattern of a series of '1's and '0's. Millipede reads the data back by scanning the substrate with the same matrix, and measuring the resistance between the AFM tips and the substrates. Tips that are over a hole will have a higher resistance than tips over the unchanged substrate. Millipede can also change the data on the substrate, by erasing the indents.
In one test, IBM managed to write the word 'IBM' using 50nm dots with an effective aerial density of almost 1Tb/sq in. The main issue with millipede is that it is about 1000 times slower than magnetic disk. This needs to improve for millipede to compete in the mainstream storage arena.

IBM foresees two main applications for millipede; applications that need very small storage devices, like watches or mobile phones, and applications that require terabytes of storage. Millipede could scale up either by producing chips with say 1,000,000 cantilevers, but it would be easier to use lots of smaller millipede chips in parallel. Another approach would be to create the polymer coat on a modified hard disk, which could result in a 2.5 inch disk with several terabytes capacity.

Near Field Storage

Uses a combination of optics and electromagnetics. An optical read/write head moves over the surface of the disk, but the laser beam is very tightly focused by a solid immersion lens inside the head. This 'melts' the surface of the disk, and data is then written magnetically, by a magnetic coil inside the head.

Far Field Storage

This one uses a combination of fibre optical pipes to transfer the data, lasers to write data, and magnetic fields to store it. Data is written by heating a spot on the disk, which is then magnetised. Data density could be up to 200 Gbits / square inch.

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