Nanomechanical Memory Outstrips Chip Technology

By Roland Piquepaille

This sounds almost too good to be true -- at least for some time. Physicists from Boston University have fabricated nanomechanical switches which promise fantastic advances in data storage. Their nanodevices will have densities exceeding by orders of magnitude existing storage devices. They will deliver data at speeds in the megahertz (and possibly gigahertz) range, also exceeding by far the few hundred kilohertz of our current hard drives. And finally, they will only use some femtowatts of power each, leading to hard drives consuming maybe a million times less electricity than existing devices. So, where's the catch? Will we ever see hard drives built with these nanomechanical switches? Honestly, I don't know, but read more...

Here are some selected and edited excerpts of this news release.

Pritiraj Mohanty and his group have updated an "old" technology in a bid to build better, faster data storage systems for today's computers. They have "carved tiny switches out of silicon, fabricating mechanical switches that are thousands of times smaller than a human hair."

How did they build thes nanoswitches?

The researchers used electron-beam lithography to produce the beam-and-pad design of the tiny devices, carving the switches from wafers made of single-crystal layers of silicon and silicon oxide. E-beam lithography, developed for use by the integrated circuit industry, has become a staple fabrication technique for microelectromechanical (MEMS) devices, the ultra-small sensors, switches, and gears integral to the microtechnology and nanotechnology industries.

To test the device's capabilities, the researchers clamped the nanostructure on each end, effectively suspending the beam, then drove a megahertz-frequency current through an attached electrode. When driven strongly enough, the beam switched between two different and distinct states, the needed "0" and "1" conditions commonly used to describe the process for accessing stored data.

And what about their claims for fast data delivery and ultra-small power consumption? The researchers answer.

The tiny dimensions of the device allowed it to vibrate quickly, achieving a millions-of-cycles-per-second frequency of 23.57 megahertz. This speed reflects the rate at which the device could "read" stored information. As a comparison, the hard drives in current laptops can read at a speed of a few hundred kilohertz (thousands of cycles per second) in actual operation. The researchers speculate that even smaller beams could be produced and that such devices could achieve true read speeds in the gigahertz range -- billions of cycles per second.

Other advantages of this tiny mechanical memory system include its angstrom-sized "range of motion," allowing it vibrate between states using only femtowatts of power, compared with the milliwatts or microwatts of power needed for read-write functions in current machines. The device also overcomes the superparamagnetic effect that limits contemporary systems, allowing the beams to be packed at densities that exceed the 100 gigabits per square inch that is the current ceiling.

The team doesn't say if or when these nanoswitches will leave their la to come to our hard drives. But my feeling is that these kind of 'nanomechanical memory' will not reach mass production before many years. If you have more clues about this technology, please leave a comment.

Sources: Boston University news release, September 30, 2004; and various other websites