Researchers in the US have developed a better way to harvest the magnetic energy that is all around us.
The team at Penn State developed a device that provides four times the power output of other technology when working with low-level magnetic fields from electrical equipment in homes and buildings. This energy is then used to power sensor networks.
The paper-thin generator is 35mm long and can be placed on or near appliances, lights, or power cords where the magnetic fields are strongest. These fields quickly dissipate away from the source of flowing electric current.
It uses a composite of a 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 turn a magnetic field into an electric current.
The generator produces milliwatt power in a stray magnetic field below 300 μT. The output power from extremely low magnetic fields under 50 μT is sufficient to power hundreds of light emitting diode (LED) arrays and operate a digital clock without charging a capacitor.
“These results provide significant advancements toward sustainable power for integrated sensors and wireless communication systems,” said Min Gyu Kang, an assistant research professor at Penn State and co-lead author on the study.
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 contributes toward a higher production of electricity.
“We have this ubiquitous energy present in our homes, office spaces, work spaces and cars. It’s everywhere, and we have an opportunity to harvest this background noise and convert it to useable electricity,” said Shashank Priya, professor of materials science and engineering and associate vice president for research at Penn State. “In buildings, it’s known that if you automate a lot of functions, you could actually improve the energy efficiency very significantly,” said Priya. “Buildings are one of the largest consumers of electricity in the United States. So even a few percent drop in energy consumption could represent or translate into megawatts of savings. Sensors are what will make it possible to automate these controls, and this technology is a realistic way to power those sensors.”
“The beauty of this research is it uses known materials, but designs the architecture for basically maximizing the conversion of the magnetic field into electricity,” said Priya. “This allows for achieving high power density under low amplitude magnetic fields.”