Smart Dust

The particles of dust that could be watching you

The world's going all sci-fi on us again. Last month it was cloning and biotech, now it's super-surveillance technology. If you thought RSA and PGP had made all of us safe from prying eyes and ears, think again: those motes that just drifted in the window and floated down through the shards of sunlight cutting through your office - in a year or two those might be particles of Smart Dust, and they could be watching you.

Like something out of a Neil Stephenson novel, Smart Dust is the brainchild of Associate Professor Kris Pister and Professor Randy H. Katz, who are currently working out of the University of California, Berkeley. It relies on the convergence of three technologies: digital circuitry, laser-driven wireless communications, and something called MEMS (Micro ElectroMechanical Systems) to pack enough equipment into a space no more than one or two cubic millimeters in size.

Intelligent motes

Already, Pister's team has managed to cram a semiconductor laser diode and MEMS beam-steering mirror for active optical transmission, a MEMS corner-cube retroreflector for passive optical transmission, an optical receiver, signal-processing and control circuitry and a power source based on thick-film batteries and solar cells into a mote that's only five millimeters long, a length they are confident that they can more than halve. With clever power management techniques, each mote should be able to stay active for several days.

The challenge is to ensure that motes distributed in a space can communicate with each other and with a base station called a base-station transceiver (BTS) equipped with a compact imaging sensor. This could be mounted in close proximity to the motes, say in a wall-mounted camera, or perhaps in a remote controlled aircraft or a pair of binoculars. Using a passive light transmitter that reflects back modulated light bouncing off it from an external source - which has the advantage of keeping energy requirements to the minimum - a mote can send data at a rate of 1 kilobit a second over distances of up to 150m. But communication distances of over 20kms have also been successfully tested, although bit rates drop off sharply. It is not inconceivable that motes could be fitted with minaturised microphones or tempest attack technology - a tempest attack being an attempt to detect the distinct electromagnetic signal a computer gives out each time a key is pressed, apparently a regular feature of FBI surveillance nowadays - and used as almost undetectable spying devices.

Motes could be delivered to their destination by a fancy technology like a miniature rocket or a natural one as innocuous as a sycamore leaf.

Numerous civilian and military applications

Pister envisons 'numerous civilian and military applications for Smart Dust. Smart Dust may be deployed over a region to record data for meteorological, geophysical or planetary research. It may be employed to perform measurements in environments where wired sensors are unusable or lead to measurement errors... In biological research, Smart Dust may be used to monitor the movements and internal processes of insects or other small animals. Considering the military arena, Smart Dust may be deployed for stealthy monitoring of a hostile environment, e.g. for for verification of treaty compliance. [With] acoustic vibration or magnetic field sensors [it] could detect the passage of vehicles ... [it] could be used for perimeter survelliance, or to detect the presence of chemical or biological agents on the battlefield.'

Pister also thinks it's got a major role to play in the wireless sensor networks that he predicts will dominate the "post-PC era", soon to be upon us no doubt.

The guy who wired the White House

Good sales pitch, huh? But to achieve any of this Smart Dust needs more than just minaturisation. It also needs networking software powerful enough to enable ensemble behaviour, preferably with emergent or 'swarm' characteristics. That's where Pister's partner, Randy Katz, comes in. With an impressive CV in major industry and military computing innovation already behind him, Katz's most recent research has focused on wireless communications, mobile computing applications and collaboration technology. He designed the network architecture for the Berkeley InfoPad Project and in 1995 he was awarded a DARPA contract to develop a wireless overlay internetworking architecture, making it possible to integrate in-building and wide-area wireless data networks.

He is currently working with several companies, including Daimler Benz, Ericsson (data over cellular), Fuji Xerox, Hughes (direct broadcast satellite), Hybrid Networks (wireless cable), and Metricom (multi-hop packet radio), to deploy this overlay technology in a Bay Area testbed. In 1996, he received additional DARPA funding to develop room-sized collaboration technology. He has won three best paper awards for his work in mobile computing and collaboration technologies. And get this: back 1993 he was the guy who wired the White House and set up the first email accounts for Clinton and Gore at I'd advise investing in Smart Dust right now. And buy a new vaccuum cleaner. It's going to be big. (James Flint)