In today’s wireless world, Wi-Fi signals are everywhere; from coffee shops to your own bathroom, the need for mobile devices to stay connected to the internet has made the presence of these Wi-Fi signals ubiquitous. Of course, in an effort to cast a wide net of wireless networks and with data privacy concerns on the rise, individual networks and connections by single persons or families often result in several Wi-Fi connections coinciding in one spot, despite devices only ever really using one at a time. This leads to a lot of unused wireless signals. In response to this, engineers have developed technology that can harness these unused wireless signals to power small tech, according to a study published under Nature Communications.
The study, spearheaded by Yang Hyunsoo, a professor from the Department of Electrical and Computer Engineering, National University of Singapore (NUS), engineered these devices called spin-torque oscillators (STOs) to harvest wireless signals, powering an LED bulb wirelessly without the use of a battery or an alternative power source. The project is a collaboration between NUS and Japan’s Tohoku University (TU), shared among teams led by Yang, Guo Yong Xin, also from NUS, and Shunsuke Fukami from TU.
STOs are emerging technologies that generate microwaves, and have applications in wireless communications systems. However, their applications are limited due to various reasons, one of which being its low power output. Synchronizing multiple STOs can alleviate this problem; however, it adds spatial restrictions to the list of issues one must be mindful of. To address these several issues, the collaboration arranged eight STOs in series. In doing so, the array of STOs gathered 2.4-GHz (gigahertz) electromagnetic radio waves broadcasted from a Wi-Fi source, being converted into a voltage signal that gets transmitted to a capacitor. After 5 seconds of charging, the capacitor was able to light up a 1.6-V (volt) LED bulb for one minute, even after the wireless power source was switched off.
Dr. Raghav Sharma, first author of the study, shares his insights on the significance of the results, saying that “these results are important for prospective applications of synchronized STOs, such as fast-speed neuromorphic computing.” Further improvements to the study are being conceptualized, including potentially increasing the number of STOs in the array, as well as testing their newly-engineered harvesters on other functional electronic devices and sensors. The collaboration also hopes to work in tandem with industry partners, especially in exploring the possibility of on-chip STOs for self-sustained smart systems, which may help pave the way for new wireless charging and wireless signal detection applications.
Bibliography
- National University of Singapore. (2021, May 18). Engineers harvest WiFi signals to power small electronics. ScienceDaily. Retrieved August 25, 2021, from https://www.sciencedaily.com/releases/2021/05/210518114153.html
- Sharma, R., Mishra, R., Ngo, T. et al. Electrically connected spin-torque oscillators array for 2.4 GHz WiFi band transmission and energy harvesting. Nat Commun 12, 2924 (2021). https://doi.org/10.1038/s41467-021-23181-1
