Engineers devise a method of powering small electronics using Wi-Fi signals

Over the last handful of years, the number of electronic signals floating through the air has vastly increased worldwide. One of the extremely common signals emitted by electronic devices today is Wi-Fi, typically used to send data without wires between computers and other devices. With an abundance of Wi-Fi signals using a 2.4 gigahertz radio frequency, researchers have been looking into ways to tap into those signals for other purposes.

A team of researchers from the National University of Singapore and Tohoku University in Japan has developed technology featuring tiny smart devices known as spin-torque oscillators to harvest and convert wireless radio frequencies into energy capable of powering small electronics. The researchers were able to successfully harvest energy using Wi-Fi band signals to power an LED wirelessly without a battery.

Researchers on the project say Wi-Fi signals surround us, but when not used to access the Internet, they are inactive and pose a significant waste. The results of the study show hardware can be manufactured that is able to turn 2.4 gigahertz radio waves into a green source of electricity. Converting those radio waves into electricity could reduce the need for batteries to power small gadgets and sensors.

This technology can be a huge boost to the Internet of Things and help push the advancement of smart homes and cities. Spin-torque oscillators are a class of emerging devices able to generate microwaves with applications in wireless communication systems. Typically the devices are hindered due to a low output power and broad linewidth. Researchers note that spin-torque oscillators have spatial restrictions. To overcome the spatial and low-frequency limitations of the devices, the team came up with an array of eight spin-torque oscillators connected in a series.

With the array, the 2.4 gigahertz electromagnetic waves emitted by Wi-Fi devices can be converted into a direct voltage signal transmitted to a capacitor to light up a 1.6-volt LED. When the capacitor was charged for at least five seconds, it could light the LED for one minute after the wireless power was disconnected. The next step for the technology is to enhance the energy harvesting ability, and the team is looking for ways to increase the number of spin-torque oscillators in the array.