Future wireless networked sensors may, literally, be everywhere, as retail managers put tiny tags on merchandise to track inventory and soldiers sprinkle "smart dust" on battlefields to monitor conditions and threats. Now Dust, a spinoff of the University of California, Berkeley, is close to marketing the world's smallest networked sensors.

Just four square millimeters, one of the company's "nodes" combines little sensors-which can detect things like temperature, light, or chemicals-with a microprocessor, lithium battery, solar cell, radio transceiver, and memory, all on a silicon chip. It's a "technical tour de force," says Kevin Delin, an expert on sensor systems at NASA's Jet Propulsion Laboratory.

This feat of shrinkage, led by Berkeley electrical engineers Kris Pister and Jason Hill, cofounders of Dust, has as much to do with software as hardware. The software on each node cooperatively manages data storage and transmission with other nodes to minimize overall power consumption. This allows each node to use smaller batteries. The designs of the processor and radio were also optimized to keep power usage to a minimum. Dust plans to commercialize its sensor nodes within a year for customers to test. Other companies, including Intel and Crossbow Technology in San Jose, CA, are also creating tiny sensor nodes. The question now is what applications will take hold.