If mirkin can be described as a nano scribe, IBM electrical engineer Peter Vettiger is a nano boxer, using AFM tips to punch at a soft polymer surface. Working in the same IBM Research lab in Zurich that helped invent the AFM in 1986, Vettiger and co-workers have built a data storage device that uses an array of 1,024 tiny AFM probes to make indentations in the polymer, each divot “writing” a bit of information no more than 50 nanometers in diameter. The scientists then use the same array of tips to rapidly read the indentations and erase them as needed.
For those pondering the future of information technology, the IBM work is exciting because storing a bit of data at that scale translates into the ability to pack immense amounts of data into a very small area. Today’s best storage products (based on magnetic memory) hold about two gigabits per square centimeter, and physicists believe the limit of magnetic memory is around 12 gigabits per square centimeter.
Results from Vettiger’s prototype, nicknamed “Millipede,” suggest the AFM-based memory could smash those limits. In tests done last year, the IBM scientists achieved a density of 35 gigabits per square centimeter (up to 80 gigabits per square centimeter using a single AFM tip), reading and writing the information at a speed that rivals existing magnetic devices. Such a density of information could make it possible, by integrating millions of tips together, to produce a hard drive with terabytes of memory-about 40 times greater than what is now commercially available. So far, says Vettiger, there aren’t any “show-stoppers” to achieving that vision.
Even more intriguing for those interested in pervasive computing, the technology could mean packing a few gigabytes (enough memory to hold a thousand high-resolution photographs or a thousand 200-page books) onto a device the size of a wristwatch. The advent of ubiquitous computing will create new markets for ultrasmall hard drives, particularly for mobile products such as cell phones and watches. Last summer, for example, IBM introduced a product called Microdrive that packs a gigabyte onto a miniaturized magnetic hard drive roughly the size of a matchbox. But, says Vettiger, the Millipede technology could go far beyond that, making gigabyte hard drives as small as a square centimeter. Equally important, he says, this AFM-based “nanodrive” will require less energy to operate than a magnetic hard drive-a critical factor in portable products.
The prospect of watching videos on his wristwatch, however, is not what drives Vettiger. Building the Millipede prototype proved the IBM technologists could integrate a large number of AFM tips with the electronics required to control them-and do it all on a small chip. Millipede is, in effect, a chip in which microelectronics are combined with micromechanics. And, says Vettiger, it could be possible to build a “smart” version of Millipede that intelligently searches its ultradense heap of data for patterns. “You now have millions of transistors on a chip. You can build the same number of mechanical devices on a simple chip, providing functions that electronics can’t do,” he says. “I’m very confident that in Millipede you’re just seeing the tip of the iceberg.”