Scientists convert Wi-Fi signals into electricity using a flexible device: Here's how

MIT scientists have developed first fully flexible device that can convert energy from Wi-Fi signals into electricity, paving way for wirelessly powering everyday electronics without batteries.

Devices that convert AC electromagnetic waves into DC electricity are kwn as "rectennas." 

researchers demonstrate a new kind of rectenna, described in a study appearing in journal Nature, that uses a flexible rio-frequency (RF) antenna that captures electromagnetic waves -- including those carrying Wi-Fi -- as AC waveforms.

antenna is n connected to a vel device me out of a two-dimensional semiconductor just a few atoms thick. AC signal travels into semiconductor, which converts it into a DC volt that could be used to power electronic circuits or recharge batteries.

In this way, battery-free device passively captures and transforms ubiquitous Wi-Fi signals into useful DC power. Moreover, device is flexible and can be fabricated in a roll-to-roll process to cover very large areas.

"What if we could develop electronic systems that we wrap around a bridge or cover an entire highway, or walls of our office and bring electronic intelligence to everything around us? How do you provide energy for those electronics?" said Tomas Palacios, a professor at Massachusetts Institute of Techlogy (MIT) in US.

"We have come up with a new way to power electronics systems of 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 Palacios.

Promising early applications for proposed rectenna include powering flexible and wearable electronics, medical devices, and sensors for "internet of things." 

Flexible smartphones, for instance, are a hot new market for major tech firms. In experiments, researchers' device can produce about 40 microwatts of power when exposed to typical power levels of Wi-Fi signals (around 150 microwatts).

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That is more than eugh power to light up a simple mobile display or silicon chips.

Ar possible application is powering data communications of implantable medical devices, said Jesus Grajal, a researcher at Technical University of Mrid. 

For example, researchers are beginning to develop pills that can be swallowed by patients and stream health data back to a computer for diagstics.

"Ideally you don't want to use batteries to power se systems, because if y leak lithium, patient could die," Grajal said.

"It is much better to harvest energy from environment to power up se small labs inside body and communicate data to external computers," he said.

research provides blueprints for flexible Wi-Fi-to-electricity devices with substantial output and efficiency. maximum output efficiency for current device stands at 40 per cent, depending on input power of Wi-Fi input. 

At typical Wi-Fi power level, power efficiency of rectifier is about 30 per cent. For reference, today's best silicon and gallium arsenide rectennas me from rigid, more expensive silicon or gallium arsenide achieve around 50 to 60 per cent.

team is w planning to build more complex systems and improve efficiency.