A team of researchers has developed an innovative method to capture energy from ambient radio waves, making it possible to power wearable health-monitoring devices without relying solely on conventional energy sources.
Wearable devices currently depend on technologies like solar power and triboelectric systems, but both have limitations. Solar energy can only be harvested under sunlight, while triboelectric devices generate power only when the wearer is in motion.
“Radio waves surround us constantly — they’re everywhere, all the time,” explained Huanyu “Larry” Cheng of Penn State University, US, who led the study. “If we don’t tap into this ambient energy, it goes to waste. Our system allows us to harvest and convert it into usable power.”
The research, published in Materials Today Physics, describes a stretchable wideband dipole antenna system designed to wirelessly transmit data from wearable sensors. This system integrates two flexible metal antennas with conductive graphene coated in metal, enabling the device to maintain performance even when stretched, bent, or twisted.
By linking the antennas to a flexible rectifying circuit, the team created a “rectenna” — a rectifying antenna that can convert electromagnetic energy into electricity. This power can either run wearable health sensors directly or be stored in batteries and supercapacitors for later use.
The rectenna enables continuous power generation from surrounding radio waves, providing energy for sensors that monitor vital signs such as body temperature, hydration levels, and blood oxygen saturation. Although the amount of energy harvested is lower than solar or motion-based methods, the advantage lies in its ability to deliver a steady, uninterrupted supply of power.
According to the researchers, this breakthrough could pave the way for more reliable and long-lasting wearable health-monitoring systems, reducing dependence on batteries and external charging sources.
