In the modern world, radio waves are exceedingly common and surround us at all time. Think of WiFi access points, cell phone towers, to microwave ovens; they all produce radio waves. Scientists at Penn State University have established a method to collect energy from these radio waves to charge wearable gadgets. They published their findings in the science journal: Materials Today Physics.

Radio waves are a more reliable power source for wearable gadgets than, for example, solar power - Credit: iStock/Getty Images - HDR tune by Universal-Sci

Currently, there are several ways of changing wearable devices without falling back on a wall charger. Each of these methods has its own drawback or weak spot. Solar power, for instance, can only collect energy when there is sunlight, and a self-powering triboelectric device can only harvest energy when the body is in motion. The idea behind radio wave charging is not to replace these charging methods but to supplement them.

The Penn State scientists created a stretchable wideband dipole antenna system consisting of 2 stretchy metal antennas integrated onto conductive graphene material that has a metal coating. The wideband design of the system enables it to preserve its frequency functions even when it gets twisted or stretched. This system is then connected to a stretchable rectifying circuit establishing a so-called rectenna. A rectenna is a rectifying antenna — a particular variety of receiving antennas that is capable of converting electromagnetic energy into direct current, which can then be utilized to charge small batteries or wireless devices.

Like the previously mentioned contemporary ways to charge wearable devices, this radio wave method also has its own weakness; it generates less power. However, it also has a notable advantage, namely its ability to produce power consistently as radiowaves are around us all the time.

Huanyu Cheng, lead author of the paper, stated in a press release that this new technology harvests power that is readily available around us. If the ambient radio wave energy is not used, it is just wasted. It is possible to harvest this energy and reform it into power.

The research team is already looking into building upon their newly developed technology. They aim to create miniaturized versions of these circuits while improving the stretch-ability of the rectifier. It is very well possible that new additional use cases will be found as, according to Cheng, the technology is easily adaptable for other applications.

If you are interested in a more detailed description of the work that Cheng and his colleagues did, be sure to check out the paper listed below!

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