ENSOR IS A "SPEC" 3.8 WIRELESS SENSOR IS A "SPEC" Ultimately, a mesh network is only as good as the sensors it incorporates. Small, lower-power sensors are the keys to making a mesh network more useful and productive. Adhering to this principle, University of California (UC) at Berkeley researchers have developed a wireless sensor that can fit on a fingertip. The device, dubbed "Spec," is a "mote"-a wireless sensor platform that measures a mere 5 mm². Massive numbers of these tiny devices could be used in self-organizing wireless sensor networks for such innovative applications as monitoring seabird nests in remote habitats, pinpointing structural weaknesses in a building after an earthquake, or alerting emergency workers to the pres- ence of biochemical toxins. "Spec is our first mote to integrate radio frequency communication and custom circuits onto a chip that runs the TinyOS operating system," says Kris Pister, a UC Berkeley professor of electrical engineering and computer sci- ences and the researcher heading the project. "It's a major step towards sensors that cost less than a dollar apiece and that are integrated into the prod- ucts that we own, the buildings that we live and work in, and the freeways we drive on. The potential for such sensor networks is enormous." What's remarkable about Spec is the range of components the researchers were able to fit onto a single chip and its system-driven architecture. Spec combines a micro-radio, an analog-to-digital converter, a temperature sensor, and the TinyOS operating system onto a piece of silicon 2 by 2.5 mm². "This is the first fully integrated and fully operational mote on an individual chip," says David Culler, a UC Berkeley computer science professor. "Single chip integra- tion makes the mote very cheap because it reduces post-assembly requirements. This opens the path to very low cost deployments of a large number of motes." Researchers tested the new chip at the Intel Research Laboratory in Berkeley. Spec was able to transmit radio signals at 902MHz ov