Scientists harness unused energy source to power smart sensor networks


UNIVERSITY PARK, PA – The electricity that lights our homes and powers our appliances also creates small magnetic fields that are present all around us. Scientists have developed a new mechanism capable of capturing this wasted magnetic field energy and converting it into enough electricity to power next-generation sensor networks for smart buildings and factories.

“Just as sunlight is a free source of energy that we try to harvest, so too are magnetic fields,” said Shashank Priya, professor of materials science and engineering and associate vice president for research. at Penn State. “We have this ubiquitous energy present in our homes, offices, workspaces and cars. It’s everywhere, and we have the ability to harvest that background noise and convert it into usable electricity.

A team led by scientists at Penn State has developed a device that provides 400 percent more power output than other advanced technologies when working with low-level magnetic fields, such as those found in the field. found in our homes and buildings.

The technology has implications for the design of smart buildings, which will require self-powered wireless sensor networks to do things like monitor energy and operational models and remotely control systems, the scientists said.

“In buildings, we know that if you automate a lot of functions, you could actually improve energy efficiency very significantly,” Priya said. “Buildings are one of the biggest consumers of electricity in the United States. So even a drop of a few percent in energy consumption could represent or translate into megawatts of savings. The sensors are what will automate these controls, and this technology is a realistic way to power these sensors. “

Researchers have designed paper-thin devices, about 1.5 inches long, that can be placed on or near devices, lights, or power cords where magnetic fields are strongest. . These fields dissipate quickly from the source of electric current, the scientists said.

When placed 4 inches from a heater, the device produces enough electricity to power 180 LED arrays, and at 8 inches, enough to power a digital alarm clock. The scientists reported the results in the journal Energy and Environmental Science.

“These findings provide significant advances towards sustainable energy for integrated sensors and wireless communication systems,” said Min Gyu Kang, assistant research professor at Penn State and co-lead author of the study.

The scientists used a composite structure, superimposing two different materials. One of these materials is magnetostrictive, which converts a magnetic field into stress, and the other is piezoelectric, which converts stress, or vibrations, into an electric field. The combination allows the device to transform a magnetic field into electric current.

The device has a beam-like structure with one end clamped and the other free to vibrate in response to an applied magnetic field. A magnet mounted at the free end of the beam amplifies the movement and helps in higher electricity production, the scientists said.

“The beauty of this research is that it uses known materials, but designs the architecture to essentially maximize the conversion of the magnetic field to electricity,” Priya said. “This allows high power density to be achieved under low amplitude magnetic fields.”

Rammohan Sri Ramdas, assistant research professor at Penn State, participated in the research.

Hyeon Lee and Prashant Kumar, research assistants at Virginia Tech, and Mohan Sanghadasa, senior researcher at the Aviation and Missile Center, US Army Combat Capabilities Development Command, also contributed.

Some of the team members for this study were funded by the Office of Naval Research and the rest by the National Science Foundation.


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