New networks take nature’s pulse

The hand-sized yellow objects poking up among the lush canopies at Camalie Vineyards aren’t a new variety of monster grape. They’re electronic devices that can sense soil moisture.

Viticulturist Mark Holler says these wireless sensors sprinkled throughout the leaves help him manage the high cost of irrigation and improve his yield.

“Wireless sensor networks extend the Internet ... out into the environment,” says Mr. Holler, a retired Intel technologist who owns and runs the 4.4-acre vineyard in Napa, Calif.

While the networks won’t necessarily make someone a better vintner, they do have a practical side: During the 2007 drought in California, Holler figures the technology saved him several thousand dollars in water costs.

Electronics weren’t originally outdoor friendly. Rain and dust wreak havoc on computer circuits. Cables and power problems snarled early attempts at open-air networks. But as Wi-Fi and solar panels grew more popular, inventors started looking outside. Now, power-sipping wireless sensor networks are cropping up in more and more outdoor venues.

In Antarctica and California’s Sierra Nevada mountain range, they measure snowpack. On volcanoes in Ecuador, they sense tremors. In Australia, they track invasive cane toads. And in Cambridge, Mass., they sit atop buildings and street lights to monitor weather changes and air pollution.

“The potential is unfathomable,” says Kirsten West, principal analyst at West Technology Research Solutions in Mountain View, Calif. With no wires to hold back innovation, “you don’t have to worry about the physical network.”

Already a $120 million market, networked outdoor sensors will benefit from a boom in low-power microchips. Ms. West estimates that demand for the latest chips will grow 34-fold to $680,000 by 2013.

“The market is still relatively small, but the pieces are all there,” says David Culler, a wireless sensor network pioneer and computer science professor at the University of California at Berkeley.

The networks that originated in university labs like his are now reliable enough that they have moved into mainstream uses in homes, buildings, factories, and the environment. The industry still needs established standards to assure that networks can talk to each other and longer battery life to keep them running.

The improvements to outdoor technology have been readily evident at Camalie Vineyards. Only a few years ago, Holler was wrapping each device’s circuit board in aluminum foil to protect them from rain, dust, and ultraviolet rays. The makeshift electronics looked better at scaring off crows than sending data. Now, he buys the circuitry snugly sealed inside yellow plastic cases, each topped with a small solar panel that can recharge the batteries.

With limits to battery power, it’s also important to conserve energy use in the wireless network.

“The sensors are automatically power-managed by our device,” says Mike Horton, president of Crossbow Technology of San Jose, Calif., which makes the solar-powered eKo sensors that Holler uses.

Soil, temperature, and other conditions can vary across the vineyard, so Holler has set up 32 network stations or nodes. Each has the eKo circuit board mounted atop a six-foot post and wired to three sensors buried in the soil at depths of one, two, and three feet.

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