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Radiation from electronic appliances can be used to power IoT devices

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The small magnetic fields that resonate from the lights and appliances in our homes can now be harvested to power IoT devices thanks to a newly developed device.

A team of scientists at Penn State University, USA, said their device is capable of providing 400 per cent higher power output compared to other similar mechanisms.

“Just like sunlight is a free source of energy we try to harvest, so are magnetic fields,” said Professor Shashank Priya.

“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.”

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 patterns and remotely control systems, the scientists said.

“In buildings, it’s known that if you automate a lot of functions, you could actually improve the energy efficiency very significantly,” Priya said.

“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 new paper-thin devices are roughly 4 centimetres long and can be placed on or near appliances, lights, or power cords where the magnetic fields are strongest; these fields quickly dissipate once a short distance from the source.

When placed 10cm from a space heater, the device produced enough electricity to power 180 LED arrays, and at 20cm, enough to power a digital alarm clock.

“These results provide significant advancements toward sustainable power for integrated sensors and wireless communication systems,” said assistant research professor Min Gyu Kang.

The scientists used a composite structure, layering two different materials together. 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 turn a magnetic field into an 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 contributes toward a higher production of electricity, the scientists said.

“The beauty of this research is it uses known materials, but designs the architecture for basically maximising the conversion of the magnetic field into electricity,” Priya said. “This allows for achieving high power density under low amplitude magnetic fields.”

Another team of researchers recently demonstrated indoor solar cells that can harvest energy from lamps and electric lights that could also be used for IoT devices.

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