"Smart Dust" Sensors to Be Used for Eco Detection

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At the James Reserve, nestled in the mountains of southern California, Hamilton oversees a pioneering project in which arrays of larger but smarter sensors watch the minutiae of life, revolutionizing ecological studies.

"The James Reserve is this wonderful technology playground now," Hamilton said.

The reserve is collaborating with the Center for Embedded Network Sensing at the University of California, Los Angeles, where center researchers build all sorts of experimental equipment.

"We get to try out everything from very small wireless devices for measuring microclimate, [to] development of miniature camera systems … that can detect patterns in animal behavior or … color changes that might relate to flowering," Hamilton said.

They also have inconspicuous cameras watching birds' nests to monitor how many eggs hatch.

Birds' reproductive success is closely tied to climate, since the temperature has to be in the right range for eggs to develop properly and for the birds to find enough food to feed their hatchlings.

(Related news: "Early Birds: Is Warming Changing U.K. Breeding Season?" [June 3, 2003].)

The system has revealed that "there's a lot more nest failure than we expected," Hamilton said. Before, the team simply couldn't keep track of how many eggs failed to hatch, and "we didn't know why they failed."

Now the researchers can answer such questions, and hope to someday use their fine details to put together answers to big issues in ecology.

"The holy grail of all this is: Can we forecast change?" Hamilton said.

Smart Sand

Meanwhile, Sailor, the UCSD chemist, is striving to create cheaper, smaller, cleverer motes that would also address environmental problems.

One of his group's main projects could be called smart sand.

His team's sensors are engineered at the nanoscale—the size of molecules—and are cheap because they're etched out of flakes of silicon, the stuff of computer chips and beaches.

"They're basically made of sand," Sailor said.

Sailor's smart sand reflects a specific color of light because it's made in extremely thin layers. The same effect gives beetles and butterflies their iridescent colors.

But unlike insects' bodies, Sailor's sand-size sensors change colors when they come in contact with certain chemicals.

"We've made sarin-gas detectors," Sailor said, referring to the nerve gas that the Aum Shinrikyo cult used in a set of subway attacks in Japan in 1995, and Sailor's group is working on many more.

Sailor envisions using such particles to test water for bacterial contamination.

The devices could also be injected into people to find tiny cancerous tumors before they're large enough to show up on other tests.

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