Scientists convert Wi-Fi signals into electricity to charge devices

Wireless charging, which we often refer to, generally refers to wireless power transmission technology. For example, wireless charging of mobile phones, watches and other devices is mainly achieved through the principle of electromagnetic induction. However, a scientific team from the National University of Singapore and Tohoku University in Japan published a new paper in the journal Nature showing that they have been able to convert Wi-Fi signals into energy and charge electronic devices.

Scientists have developed a "self-torque oscillator" (STO). Through this device, it is possible to capture wireless radio frequencies and convert them into energy to power some small electronic devices. Spin torque oscillators are nanoscale devices that use changes in the direction of a magnetic field to generate microwaves, but the microwaves generated by any single device are too weak for practical applications. Therefore, physicists have tried to generate reliable microwave fields by coupling large integrated circuits. To utilize this underutilized energy source, the researchers overcame the limitations of space and low frequency and used a new array in which eight spin torque oscillators were connected in series.

Through this array, the 2.4GHz radio electromagnetic waves used by Wi-Fi were converted into DC voltage signals and then transmitted to the capacitor, successfully lighting up a 1.6V LED light. When the capacitor was charged for 5 seconds, it was able to light up the same LED light for one minute after the wireless power was turned off.

The researchers are currently testing different numbers of spin-torque oscillators in the array to further enhance the technology’s energy-harvesting capabilities, and plan to test energy harvesters to wirelessly charge other electronic devices and sensors.