Harvesting Unused Energy to Power Sensor Networks

April 07, 2020 by Luke James

Researchers at Penn State University have developed a device which turns wasted magnetic energy from household devices into electricity that can power sensor networks.

This device, the researchers claim, can provide up to four times the power output of other technology by using the energy produced by standard electronics and electrical equipment found in homes and buildings. It does this by working with the small, low-level magnetic fields that are produced by electronics.

These fields can be found all around us, and the mechanism developed by the Penn State research team is capable of harvesting this would-be wasted magnetic field energy and converting it into electricity. This can then be used to power the next generation of sensor networks for smart buildings and factories. 


400 Percent Higher Power Output

The device, which is paper-thin and measures in at roughly 1.5 inches in length, can provide 400 percent higher power output in contrast to other state-of-the-art technology that works with the low-level magnetic fields that flood the world around us, the researchers claim.

It can be placed on or near to appliances, lights, and power cords where these low-level magnetic fields will be strongest and thus harvest as much waste energy as possible. 

"Just like sunlight is a free source of energy we try to harvest, so are magnetic fields," said Shashank Priya, professor of materials science and engineering at Penn State. She went on to say that the existence of this ubiquitous energy that is constantly around us presents a unique opportunity for harvesting and conversion. 


Harvesting Power from Nearby Electronics

According to the team’s research, which was published in the journal Energy and Environmental Science, when the device was placed 4 inches away from a space heater, it was able to harvest enough energy and produce enough electricity to power 180 LED arrays. At 8 inches, it could power a digital alarm clock. 


An illustration depicting the team’s device working to harvest low-level magnetic energy which it then turns into electricity to charge a phone.
An illustration depicting the team’s device working to harvest low-level magnetic energy which it then turns into electricity to charge a phone. Image used courtesy of: Kal Wang, Penn State College of Earth and Mineral Sciences, Penn State University. 


Turning a Magnetic Current into Electricity

The Penn State team used a composite structure to make the device, layering a magnetostrictive material together with a piezoelectric one. The magnetostrictive material converts a magnetic field into stress or vibrations which the piezoelectric then uses to create an electric field. This combination enables the team’s device to turn a low-level magnetic field into an electric field which can then be used to power electronics. 

The device features a beam-like structure with one end clamped and the other free to vibrate in response to a magnetic field. A magnetic is mounted at the free end of the beam and this amplifies the movement and helps achieve bigger electrical current, the team says. Its unique architecture allows for achieving high power density under low amplitude magnetic fields. 


A Significant Advancement Towards Sustainable Power? 

Buildings are already one of the largest consumers of energy, especially commercial and industrial ones like offices and manufacturing plants. With the growth of emerging tech such as artificial intelligence and the Internet of Things, they are also becoming ‘smarter’, with many already utilizing sensors for a range of control and monitoring purposes. 

The research team says that the energy harvesting device represents a significant step towards sustainable power for electronics, particularly wireless communications systems and integrated sensors. It is thought by the team that the device’s mechanism for converting magnetic field energy into electricity could be robust enough to power entire sensor networks for next-generation smart buildings and factories.