An international team of researchers have designed a device that converts energy from Wi-Fi signals into electricity. Their ‘rectenna’ could one day power wearable electronics, medical devices and sensors for the Internet of Things (IoT).
The device uses a flexible radio-frequency (RF) antenna that captures electromagnetic waves – including those carry Wi-Fi – as AC waveforms. According to a press release, the antenna – known as a rectenna – is then connected to a novel device made out of a two-dimensional semi-conductor only a few atoms thick. The AC signal travels into the semi-conductor, which converts it into a DC voltage that could be used to power electronic circuits or recharge batteries.
Their device makes it possible for a battery-free device to passively capture and transform Wi-Fi signals – available nearly everywhere – into useful DC power. It is flexible and can even be fabricated in a roll-to-roll process to cover very large areas. The researchers recently published a study on their new kind of rectenna in the journal Nature.
“We have come up with a new way to power the electronics systems of the future – by harvesting Wi-Fi energy in a way that’s easily integrated in large areas – to bring intelligence to every object around us,” said co-author Tomás Palacios, a professor in the Department of Electrical Engineering and Computer Science and director of the MIT/MTL Center for Graphene Devices and 2D Systems in the Microsystems Technology Laboratories.
Early applications for the proposed rectenna include flexible and wearable electronics, medical devices and IoT sensors. In experiments, their device produced about 40 microwatts of power when exposed to typical power levels of Wi-Fi signals, which is more than enough power to light up an LED.
It could even be used to power the data communications of implantable medical devices when swallowed as a pill that streams health data back to a computer for diagnostics.
“Ideally you don’t want to use batteries to power these systems, because if they leak lithium, the patient could die,” said co-author Jesús Grajal, a researcher at the Technical University of Madrid. “It is much better to harvest energy from the environment to power up these small labs inside the body and communicate data to external computers.”
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