With the rise of the digital age, the number of WiFi sources transmitting information wirelessly between devices is increasing exponentially. This makes the 2.4GHz RF used by WiFi widely used. But when people do not use WiFi to access the Internet, they are inactive, resulting in a huge waste of signal resources. In order to make full use of this idle energy, the research team of Professor Guo Yongxin of the Department of electrical and computer engineering of the National University of Singapore and the research team of Professor Shenjian Junfu of Tohoku University in Japan have developed a new technology, which uses a micro intelligent device called "spin torque oscillator" (STOs) to collect and convert radio frequency and convert it into energy, Power small electronic equipment. Relevant research results were published in the journal Nature communications in May 2021.

         STOs is a new type of microwave generating equipment, but its application is limited due to its low output power and large linewidth. In order to overcome the shortage of space and low-frequency response, the research team designed eight STOs arrays connected in series, converted the 2.4GHz wireless electromagnetic wave used by WiFi into DC voltage signal, and then transmitted it to the capacitor, which successfully lit the 1.6V LED lamp. After charging the capacitor for 5 seconds, the LED light can remain on for 1 minute even if the external power supply is cut off.