"Millipede" is a new (AFM)-based data storage concept that has a potentially ultrahigh density, terabit capacity, small form factor, and high data rate. Its potential for ultrahigh storage density has been demonstrated by a new thermomechanical local-probe technique to store and read back data in very thin polymer films. With this new technique, 3040-nm-sized bit indentations of similar pitch size have been made by a single cantilever/tip in a thin (50-nm) polymethylmethacrylate (PMMA) layer, resulting in a data storage density of 400500 Gb/in.2

High data rates are achieved by parallel operation of large two-dimensional (2D) AFM arrays that have been batch-fabricated by silicon surface-nMcromachining techniques. The very large scale integration (VLSI) of micro/nanomechanical devices (cantilevers/tips) on a single chip leads to the largest and densest 2D array of 32 x 32 (1024) AFM cantilevers with integrated write/read storage functionality ever built. Initial areal densities of 100200 Gb/in.2 have been achieved with the 32 x 32 array chip, which has potential for further improvements.

In addition to data storage in polymers or other media, and not excluding magnetics, we envision areas in nanoscale science and technology such as lithography, high-speed/large-scale imaging, molecular and atomic manipulation, and many others inwhich Millipede may open up new perspectives and opportunities. 


The current 32 x 32 array chip is just one example of the many possible designs of a data-storage system; the design and concept depend strongly on the intended It is important to note that the same data capacity can be achieved, for example, using large arrays with small cantilever pitch/scan range or, conversely, using small arrays with a larger scan range. In addition, terabit data capacity can be achieved by one large array, by many identical small ones operating in parallel, or by displacing a small array on a large medium.

Out of this wide range of design and application scenarios, we would like to explain two cases of particular interest. ah Small-form-factor storage system (Nanodrive)

IBM's recent product announcement of the Microdrive represents a first successful step into miniaturized storage systems.

As we enter the age of pervasive computing we can assume that computer power is available virtually everywhere. Miniaturized and low-power storage systems will become crucial, particularly for mobile applications. The availability of storage devices with gigabyte capacity having a very small form factor (in the range of centimeters or even millimeters) will open up new possibilities to integrate such "Nanodrives" into watches, cellular telephones, laptops, etc., provided such devices have low power consumption.

The array chip with integrated or hybrid electronics and the micromagnetic scanner are key elements demonstrated for a Millipede-based device called Nanodrive, which is of course also very interesting for audio and video consumer applications. AU- silicon, batch fabrication, low-cost polymer media, and low power consumption make Millipede very attractive as a centimeter- or even millimeter-sized gigabyte storage system.

b). Terabit drive

The potential for very high areal density renders the Millipede also very attractive for high-end terabit storage systems. As mentioned above, terabit capacity can be achieved with three Millipede-based approaches:

1) Very large arrays

2) Many smaller arrays operating in parallel

3) Displacement of small/medium-sized arrays over large media.