A team of scientists from the University of Singapore has announced the creation of a prototype energy-harvesting device that draws usable electricity seemingly out of thin air.
Designed to leverage nanoscale spin rectifier technology to capture what the device’s inventors term “waste RF” signals that exist in the air due to Wi-Fi, Bluetooth, 5G, and traditional radio signals, the novel energy harvesting system can convert those signals into enough usable direct current (DC) electrical energy.
Similar RF energy harvesting technologies have been developed in recent years, including one invented by researchers from the University of South Florida. However, the team behind this latest iteration says their device is able to capture energy from weaker overall signals (typically less than -20 dBm) than even the most sensitive RF energy harvesting technology.
“Harvesting ambient RF electromagnetic signals is crucial for advancing energy-efficient electronic devices and sensors,” explained project leader Professor Yang Hyunsoo from the Department of Electrical and Computer Engineering at the NUS College of Design and Engineering. “However, existing Energy Harvesting Modules face challenges operating at low ambient power due to limitations in existing rectifier technology.”
To overcome the limitations of similar devices, including the inefficiencies of converting such weak signals into useful electricity, the team developed their own ultra-compact, nanoscale spin rectifier technology to capture and convert the waste RF. Unlike previous attempts, this minuscule rectifier showed impressive results at converting RF signals below -20 dBm.
According to Professor Yang, his team’s efforts to improve energy harvesting at these low levels were drastically different from previous efforts. That’s mainly because of the implementation of nanoscale spin rectifiers.
“Recent efforts focused only on improving antenna efficiency and impedance-matching networks at the expense of bigger on-chip footprints,” the professor explained. “Nanoscale spin-rectifiers, on the other hand, offer a compact technology for sensitive and efficient RF-to-DC conversion.”
After trying several configurations designed to convert energy from different low yet usable EM wavelengths, the team settled on something that operated at a level of efficiency previously unseen. This result, the team explains, was due to their approach as much as the technology itself. The result was a device that successfully captured low levels of RF and converted them to enough electricity to power an electrical sensor and an LED.
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