No Limit to Connections
If you think we already live in a hyperconnected world with our smartphones and Apple watches, just wait. A Stanford professor, working with researchers at UC-Berkeley, has designed an ant-sized radio that harvests its power from incoming signals. The result is a battery-free wireless controller so small, cheap and efficient it offers a way to connect with virtually anything—from bank notes to lightbulbs.
Amin Arbabian, assistant professor of electrical engineering, began the project as a doctoral student at Berkeley focused on a fundamental quest: How small could he make a transceiver? By doing away with the normally essential guts of a radio, particularly the battery, the researchers were able to make a wireless device that's twice the size of President Lincoln's nose on a penny. The controller can be built on a single chip for a few cents per unit.
Such thrift doesn't matter for high-end items we generally think of as using wireless connection, like smartphones, Arbabian says. But it's vital if you want to reach an endless list of more mundane items.
The radio-on-a-chip, he says, could be the missing link in the "Internet of Things," the era predicted by tech watchers when everyday objects can tie to the Internet.
"We're ultimately talking about connecting trillions of devices," says Arbabian, including disposable items like adhesive bandages, which he suggests hospitals might fit with temperature sensors.
The project has drawn wide interest from industry, Arbabian notes, though for now, the radio remains more of an academic project. But in discussions about a dawning world of unlimited wireless objects, the device shows a way forward at a cost we can afford, he says.
Good Vibes Enable an Imaging First
MAKING WAVES: Data from Long Beach sensors was key. (Photo: D. Ramey Logan)
We'd give you three guesses as to what ambient-noise body-wave tomography is, but twice as many wouldn't be enough. Alternatively, we have an explanation from the geophysics researcher who's making the most of the technique.
Nori Nakata, a postdoctoral fellow at the School of Earth, Energy & Environmental Sciences, has employed the first successful use of such tomography—which involves three-dimensional imaging of the Earth's interior—in creating detailed subsurface maps to a depth of more than half a mile. "We think we can use it to image the subsurface of the entire continental United States," says Nakata.
Nakata had an idea for analyzing body waves—a type of seismic wave—that can be generated by many activities, including the routine motions of vehicles and pedestrians. The passage of body waves through the Earth has been difficult to translate into spatial representations because of their low amplitude. But Nakata figured out how to crack the problem with signal-processing software that separated high-resolution body waves from other interfering noise.
The team he led worked with data from a network of thousands of sensors installed across Long Beach, Calif., to monitor oil reservoirs. "When I saw the Long Beach data, I realized I had all the pieces in my hand to isolate body-wave energy from ambient noise," says Nakata.
The results of his team's mapping amount to "something of a holy grail in Earth imaging," says Greg Beroza, a department of geophysics professor who wasn't involved in the study. Until this work, notes Beroza, scientists were able to demonstrate only the possibility of extracting enough body waves for interior imaging of the Earth. Accomplishing it is "an immensely valuable contribution."
Co-authors of Nakata's study include Jesse Lawrence, assistant professor of geophysics, postdoctoral researcher Pierre Boue and graduate student Jason Chang.
