Data gathering on a speck of dust

Researchers from the University of California are working on ‘smart dust’; tiny electronic devices designed to gather information while literally floating on air.

Kris Pister, an associate professor of electrical engineering and computer science at UC Berkeley, is leading a team of researchers at the University of California at Berkeley that is developing ‘smart dust’; tiny electronic devices designed to capture large amounts of information about their surroundings while literally floating on air.

The idea behind smart dust is to pack advanced sensors, tiny computers and wireless communicators onto minuscule ‘motes’ of silicon that will be capable of drifting on the wind.

The motes will, Pister believes, perform functions such as monitor the environment for light, sound, temperature, chemical composition and a wide range of other information, and beam that data back to a remote base station.

MEMS are made using the same photolithography techniques used to make computer chips. But unlike computer chips, MEMS contain moving parts. Patterns are etched with light into a silicon wafer to create structures such as optical mirrors or tiny engines.

Each mote contains a solar cell to generate power, sensors that can be programmed to look for specific information, a tiny computer that can store the information and sort out which data is worth reporting, and a communicator that enables the mote to be ‘interrogated’ by the base unit. Later versions may also contain a lilliputian lithium battery so the motes can operate at night.

The smallest device researchers have developed is 62 cubic millimetres but Pister expects to shrink the devices to a cubic millimetre by July 2001.

One of the biggest hurdles the UC researchers face is building a mechanism that can perform on very low power but is still capable of sensing, sorting and sending large amounts of information. For that reason, they have designed a computer operating system called Tiny OS that can function on 512 bytes of RAM.

Smart dust devices are now capable of communicating only with a single base station, but it is envisioned that they will eventually be able to share information with each other. Such a system of ‘massively distributed intelligence’ will vastly increase their ability to organise and communicate information.

Researchers are currently exploring a number of methods for deploying smart dust.

One involves the use of tiny, unmanned aircraft that would spray motes over an area like a miniature crop duster and relay the resulting information back to a base station.

MLB, an American firm that develops experimental aircraft, has already built such a plane – an 8-inch radio-controlled aircraft equipped with a video camera that can stay aloft for 18 minutes at a speed of 60 mph.

MLB’s ‘micro air vehicle’ could be useful in battlefields where low clouds impede satellite surveillance. The tiny, unmanned plane could, it is thought, fly undetected above the battlefield, disperse a swarm of smart dust and begin relaying a stream of data about the movement of enemy troops and equipment.

The UC researchers are also exploring ways to prolong the time smart dust remains airborne by adding ‘wings’ like those on maple seeds. A cubic- millimetre-sized mote dropped at 30,000 feet would take around five hours to reach the ground, but by attaching wings, the researchers hope to extend that period two- or three-fold.

Other researchers are attaching tiny legs to the motes to create microbots or smart insects. Instead of wafting randomly through the air like dust, microbots could be programmed to perform specific tasks, such as crawling through a collapsed building to search for trapped bodies.

More on the web at: http:/robotics.eecs.berkeley.edu.