Fujitsu has developed a technique it claims will allow the company to produce hard drives with an areal data density of 1Tb per square inch - almost seven times the density of today's latest perpendicular-recording hard drives.

Fujitsu's approach is based on what the company calls 'patterned media'. Essentially, the technique uses anodised aluminium to create a pattern of holes, each holding a portion of magnetic material used to store a single bit of data. The aluminium-oxide surrounding these so-called 'nanoholes' helps magnetically insulate each bit from all the others, preventing one from affecting another, which might lead to data corruption.

Fujitsu announced the development of patterned media in June 2005. Since then, it's been working on reducing the size of each nanohole to boost the data capacity of the medium. Its latest announcement gets the pitch of each hole down to 25nm, down from 45nm in the first incarnation of the process. Fujitsu's goal is to get the size down to 13nm.

At that point, you've got a data density of 4Tb per square inch.

That's some way off. So too is the 1Tb per square inch drive, but Fujitsu has in the past said it believes it will be possible to make a hard drive with such a data density by 2010.