High
density AFM data storage is achieved at IBM in Zurich using a 32x32 array
of tiny cantilevers, each of which can write to and read from a polymer
storage medium. A single cantilever, part of an atomic force microscope
(AFM) setup, can write data with a density of 400 to 500 Gbit/in2,
some 10 times greater than is possible with current magnetic hard drive
technology. It does this when the heated cantilever bores a small (30-40
nm) conical depression or dent in the polymer sample directly beneath.
The trouble
with this approach is that it is very slow. With the new IBM "millipede"
things are speeded up by using an array of more than 1000 AFM probes (see
figure at Physics News
Graphics). Data density is as high as 200 Gbit/in2, and
potentially significantly higher, while the data rate with the current
experimental setup in the lab is about 32 kbit/sec. This is still slow
by today's fast computer speeds, but the IBM researchers (Peter Vettiger,
pv@zurich.ibm.com)
expect data rates up to Gbit/sec to result when bottlenecks with computer
interfaces are cleared up in the foreseeable future.
The likely first
applications for this new data storage system would be in cell phones,
where space, but not so much speed, is the prime consideration. (Lutwyche
et al., Applied Physics Letters, 13 November 2000; Select Article.)
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