The concept is called “smart dust,” although the instruments are still far bigger than dust motes. More formally, it’s known as a wireless sensor network.



It works this way:



Make sensors that are very cheap and very small. They can measure anything you like, from vibration to light levels; or they can perform more complicated tasks, such as taking pictures or analyzing chemicals.

Attach them to the smallest and least powerful computer that will do the job. Cut the power requirements to a bare minimum by allowing the computers to relay messages to one another, and then onto a central receiver, via radio.



Then scatter them by the dozens, hundreds or thousands to keep watch on just about anything.



Because the network examines a problem from so many vantage points, it can produce a much denser and richer picture of what is going on, researchers say.



Redwoods study made easier



In the case of the redwoods, for instance, researchers used to have to lug $3,000 worth of equipment up into a tree in a plastic box the size of an ice chest, and then connect it to a computer with hundreds of feet of wire, to get readings from one location.



But the wireless sensors cost about $200 each. For less than the cost of one old-style monitoring station, researchers climbing with the aid of ropes and other equipment can put a dozen sensors in one tree. Each takes only a few minutes to install. The sensors run for months on one set of batteries; later, researchers hope to install them in more remote redwood groves in Santa Cruz and Sonoma counties.



There’s more: The tiny computers can process some of the data along the way, handing researchers only the most important and useful bits. This simplifies analysis.



Smart dust is the brainchild of Kris Pister, a UC-Berkeley engineer who in 1997 proposed that tiny sensors and all their communications gear might be squeezed into a package about the size of a grain of sand, one millimeter on a side.



The work is being carried out by the University of California’s Center for Information Technology Research in the Interest of Society, with funding from the U.S. Department of Defense. The military potential is obvious: Thousands of tiny sensors, sprinkled in a sensitive area, could keep track of enemy movements, mark the locations of mines or monitor the conditions of soldiers.



As the idea evolves — nudged along by start-up companies in Silicon Valley, Southern California and Massachusetts — people are finding a lot of potential applications:



• A San Jose company, Digital Sun, is developing irrigation systems that know when your lawn needs water. Wireless probes are stuck into the ground to measure moisture; they send the information to a controller that turns on the sprinklers.



• UC-Berkeley engineers put 55 sensors on a three-story wood-frame building last year and tested it on a shake table in Richmond to see how it would stand up to an earthquake. They simulated the shaking of the 1994 Northridge quake in Southern California and the 1999 Izmit quake in Turkey.



The result? “It’s a good thing we live in wood-frame houses,” said Steven Glaser, a civil engineer at the university. “I wanted to buy that thing. There was very little damage.”



• In a project still in the planning stages, engineers will use a wireless network to monitor temperature, moisture and other aspects of the environment within 1,600-year-old caves along the Silk Road in western China. It’s part of an effort by the Los Angeles-based J. Paul Getty Museum to preserve the caves’ sculptures and friezes, Glaser said.
More here.