Ilaria Rosella Pagliaro A new technology based on spintronics uses Wi-Fi and Bluetooth signals to power IoT devices without batteries: this rectenna represents a step forward in sustainability, reducing waste and energy dependence
Now imagine tiny devices powered by the energy lost in the Wi-Fi and Bluetooth signals that surround us all day. This isn’t science fiction; it’s reality, thanks to a new invention called a rectenna—a rectifying antenna that converts electromagnetic waves into electricity.
This innovative rectenna uses a technology based on quantum phenomena to capture even the weakest signals and turn them into enough energy to power small devices, such as temperature sensors or Internet of Things devices.
How the Rectenna works
A rectenna is basically a device for receiving electromagnetic waves, including signals from WiFi, Bluetooth, and cellular systems, which are then converted into electrical currents. It uses an antenna that captures the oscillations of those waves as alternating current, subsequently converted into direct current through a rectifier circuit.
The novelty of this new rectenna really lies in the ability to take advantage of very weak ambient signals: from an idea born back in the 1960s-where energy would directly be wired to a device using microwaves-researchers are now focused on capturing all electromagnetic waves that are already present around us, such as those coming from our Wi-Fi routers or smartphones.
For this purpose, researchers have developed an approach based on the principles of spintronics-a branch of research about the behavior that electron spin assumes in correlation with magnetic fields. They designed a set of SR nanometric devices constituted by MTJs. The proposed components were optimized for catching common frequencies, such as those from Wi-Fi at 2.4 GHz and 5G at 3.5 GHz.
Practical applications and environmental benefits
The tests had already demonstrated that a small array of spin rectifiers could indeed supply enough energy to drive a commercial temperature sensor at a power level as low as -27 dBm-a very low value compared to the power of a normal smartphone, which sends out about 500 mW at 27 dBm.
This technology could go a long way in the IoT sector, where the need for powering a wide number of sensors and devices is always on the rise. Powering these devices with ambient signals reduces dependence on batteries, lowers maintenance costs, and improves the sustainability of wireless networks.
The developers of this rectenna emphasize that wide-scale adoption could help reduce the carbon footprint associated with IoT technologies, offering a more eco-friendly and accessible energy solution.
Source: Nature Electronics
