From microwave ovens to Wi-Fi connections, the radio waves that permeate the environment are not only signals of energy being consumed, but are also sources of energy themselves. An international team of researchers, led by Huanyu “Larry” Cheng, Dorothy Quiggle Career Development Professor at the Penn State Department of Engineering Science and Mechanics, has developed a way to harvest energy from radio waves to power portable devices.
The researchers recently published their method in The physics of materials today.
According to Cheng, current power sources for portable health monitoring devices have their place in powering sensor devices, but each has its downsides. Solar energy, for example, can only recover energy when it is exposed to the sun. A self-powered triboelectric device can only recover energy when the body is in motion.
“We don’t want to replace any of these current energy sources,” Cheng said. “We are trying to provide additional and consistent energy.”
Researchers have developed an expandable broadband dipole antenna system capable of wirelessly transmitting data collected from health monitoring sensors. The system consists of two extendable metal antennas integrated on a conductive graphene material with a metal coating. The wideband design of the system allows it to retain its frequency functions even when stretched, bent and twisted. This system is then connected to an expandable rectifier circuit, creating a rectified antenna, or “rectenna”, capable of converting the energy of electromagnetic waves into electricity. This electricity can be used to power wireless devices or to charge energy storage devices, such as batteries and supercapacitors.
This rectenna can convert radio or electromagnetic waves from the surrounding environment into energy to power the device’s detection modules, which track temperature, hydration and pulsed oxygen level. Compared to other sources, less power is produced, but the system can generate electricity continuously – a significant advantage, according to Cheng.
“We are using the energy around us already – radio waves are everywhere, all the time,” Cheng said. “If we do not use this energy found in the surrounding environment, it is simply wasted. We can harvest this energy and rectify it into energy.”
Cheng said this technology is a building block for him and his team. Combining it with their new wireless transmissible data device will provide an essential component that will work with the team’s existing sensor modules.
“Our next steps will be to explore miniaturized versions of these circuits and work on the development of rectifier extensibility,” Cheng said. “It’s a platform where we can easily combine and apply this technology with other modules that we have created in the past. It is easily extended or adapted for other applications, and we plan to explore these opportunities. “
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Material provided by State of pennsylvania. Original written by Tessa M. Pick. Note: Content can be changed for style and length.