A team of researchers from the Massachusetts Institute of Technology (USA) and the Polytechnic University of Madrid has designed the first flexible device capable of converting the energy from Wi-Fi signals into electricity. This innovative and promising invention would allow us to have a new way of powering all kinds of electronic devices , such as mobiles, tablets, laptops, without the need for batteries.
Harvesting energy from Wi-Fi signals
The device harvests and then, using new 2D materials, converts wi-fi signals into electricity in the form of a rectifying antenna (rectifying antenna ), a type of antenna that converts electromagnetic energy into direct current (DC).
The new rectena uses a radio frequency antenna to capture electromagnetic waves (such as those produced by Wi-Fi) in the form of an alternating current (AC) waveform. These are sent to a two-dimensional semiconductor that converts them into direct current (DC), producing approximately 40 microwatts. It’s not much, but it’s actually enough to power an LED or to power silicon chips.
Because the rectena is flexible, it can be deployed in large areas such as wallpaper, or used in small, portable devices such as flexible smartphones, a field that is desperately trying to emerge these days. The technology could even be used in swallowable medical implants and sensors.
“The ideal is not to use batteries to power these systems, because if they lose lithium, the patient could die,” says Jesús Grajal, from the Technical University of Madrid. “It is much better to collect energy from the environment to turn on these little laboratories inside the body and communicate data to external computers.”
It is not the first device that can convert Wi-Fi energy into electricity but the improvement in this case has been to use a different material for the rectifier, the part that converts AC to DC.
Unlike gallium or silicon arsenide, which is not only rigid but would also be expensive, scientists used molybdenum disulfide (MoS2) in flexible rectenine. It is only three atoms thick and, when exposed to certain chemicals, forces a phase transition between the semiconductor and the metallic material.
Additionally, it can capture higher frequencies than other flexible rectifiers, which cannot capture the gigahertz frequencies that the Wi-Fi network operates on.
” Such a design has enabled a fully flexible device that is fast enough to cover most of the radio frequency bands used by our everyday electronic devices, including Wi-Fi, Bluetooth, LTE and many others,” explained MIT engineer Xu Zhang. .
It is cheap?
It is relatively low cost on larger scales, so it could be used for much wider applications.
“What if we could develop electronic systems that we would wrap around a bridge or if we covered an entire highway, or the walls of our office and brought electronic intelligence to everything around us?” Asks MIT’s Tomás Palacios.
“We have devised a new way to power the electronic systems of the future: by harvesting Wi-Fi energy in a way that is easily integrated into large areas, to bring intelligence to every object around us,” concludes Palacios.
The team is now working to build larger systems and to improve the efficiency of their fabulous rectena.
Reference: Xu Zhang, Jesús Grajal, Jose Luis Vazquez-Roy, Ujwal Radhakrishna, Xiaoxue Wang, Winston Chern, Lin Zhou, Yuxuan Lin, Pin-Chun Shen, Xiang Ji, Xi Ling, Ahmad Zubair, Yuhao Zhang, Han Wang, Madan Dubey, Jing Kong, Mildred Dresselhaus & Tomás Palacios. Nature (2019). “Two-dimensional MoS2-enabled Flexible rectena for Wi-Fi Band Wireless Energy Harvesting.” DOI: https: //doi.org/10.1038/s41586-019-0892-1
