Here, the word “data stream” takes on a whole new meaning: researchers from the Massachusetts Institute of Technology (MIT), the Technical University of Madrid and other institutions have developed a method to capture and transform Wi-Fi signals into useful power for electronic devices. The idea is obvious, because the ubiquitous electromagnetic waves transport not only information but also energy.
The power supply via WLAN could be perfect for small stations, which frequently deliver messages about their position and status. As soon as energy is available, they wake up and spark their data. In logistics this could provide more transparency along the supply chain, also in remote areas without a source of power supply.
“This technology is very interesting, for example for the power supply of IoT devices in buildings,” says Erik Wirsing, Head of Global Innovation at DB Schenker. “This would make it easier to use sensors to localize or measure temperature and humidity, for example.”
Efficiencies of up to 40 percent
However, it is not easy to make use of Wi-Fi signals. Special rectifiers are necessary, which can generate DC power from high-frequency oscillations. In addition, these rectifiers need to be flexible and inexpensive. For this job, the MIT researchers use the material molybdenum disulfide to build a rectifier diode. It is only a few atomic layers thick and – in contrast to conventional semiconductor materials such as silicon or gallium arsenide – very flexible.
This “Rectenna” can generate energy from electromagnetic waves with frequencies of up to ten gigahertz, with an efficiency of up to 40 percent. Other researchers had already tried that, but had failed at high WiFi frequencies. In addition to WiFi, the MIT Rectenna could also harvest the energy of Bluetooth or LTE signals.
“#Energy from the air: Researchers are building a #Rectenna to capture #energy from # radio waves.“Tweet WhatsApp
Dreaming of electronic systems in walls and on streets
The name of the device is composed of the English words for “rectifier” and “antenna”. One of the developers, Tomás Palacios from MIT, is already dreaming of electronic systems that cover walls or roads and that could be supplied by his rectenna. Until then, it will bring wearable electronics (wearables), medical devices and sensors to life in the Internet of Things. Because for larger devices, the 40 microwatts of power that the MIT researchers were able to extract from a 150 microwatt WiFi signal are not enough. The technology is still far from powering objects such as AGVs or forklifts.