Breakthrough - Carbon Nanotubes and Electromechanical Memory
Harry Dutton
June 16th, 2009
The current (online) edition of IEEE Spectrum magazine reports a very interesting “breakthrough” in memory technology. It is reported that a team of physicists the University of California, Berkeley, has developed an electromechanical memory device based on “carbon nanotubes”. Its developers, led by Alex Zettl, claim the reliable storage of data for up to a BILLION years!
Memory states are represented by the physical position of an iron “nanocrystal” inside a hollow carbon “nanotube”. If the iron crystal is at one end of the tube then a “1″ is represented. If it is at the other then we have a “0″ state. It is said that an expected data density of 1 terabyte per square inch can be expected in practical devices!
To me this seems a major breakthrough. Long-term storage of digital data is a serious problem for the whole of society. Most records today are created in digital form. In addition, all around the world people are digitising old (paper) records and making them available on the Internet. The problem is that we really don’t have a good technology for storing digital information reliably for any reasonably long period of time.
- Data stored on any magnetic medium (tape or disk) does decay over time. Personal experience shows that “Floppy Disks” recorded in the 1990’s have already decayed to the point where they cannot be read. Some people claim that magnetic tapes might last for 100 years - past experience suggests that this is more like 20 years. Albeit if someone came up with an archival magnetic tape storage technology using a serious amount of “Forward Error Correction” then perhaps we might think about 100 years.
- CDs can be very good. But plastic decays and deforms over time and the reflective backing (critical to the operation of the CD) is usually made of aluminium. If air can get to the aluminium it decays and you get the phenomenon called “CD Rot”. This has been a problem for CDs already. However, the CD architecture contains a very high level of “Forward Error Correction” (FEC). Originally intended to overcome the problem of dust and scratches on “music CDs”, the FEC technology used is brilliant! Kodak claims a 300 year life for its archival CD’s with a “gold” reflective layer (which will not “rot”). Of course then there is the potential longevity (or lack thereof) of the dyes used in “recordable” CDs. Of course to get any kind of longevity from a CD you have to store it in a dark place with stable temperature.
- One of the ways that DVDs got their higher capacity (versus CD) was to remove some of the “Forward Error Correction”. Thus Kodak only claims 100 years for its recordable DVDs.
- Flash memories will also decay over time.
Many people make the (legitimate point) that in years to come it is very unlikely that hardware will be available that can read today’s media or that there will be software that understands it. A good point! They say that all digital media should be refreshed (by copying and perhaps re-formatting) at 10 or 20 year intervals. Most of us do this with our business information simply because we change computers every 5 years and have to migrate the data. But how many businesses just store old tapes and disks expecting that the data will be recoverable if/when the time arrives?
Nevertheless - problems of reading the media and understanding the data formats are problems for the people of the future. Today’s problem is to save the information.
With “Carbon Nanotube Storage” it seems that we finally have a way.