We've seen how stray wireless signals can be illuminated for art, but for aesthetes who want more function and less form out of the invisible networks streaming all around us, lend an ear.

A team of researchers at Georgia Tech, led by Manos Tentzeris, a professor in the university's School of Electrical and Computer Engineering, have built a simple antenna that can harvest stray energy transmitted from radio, television and cell phone signals.  

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"There is a large amount of electromagnetic energy all around us, but nobody has been able to tap into it," said Tentzeris in a university press release. "We are using an ultra-wideband antenna that lets us exploit a variety of signals in different frequency ranges, giving us greatly increased power-gathering capability."


An antenna may not sound like a very interesting device, but the cool part is that Tentzeris and his team made the antenna using an inkjet printer.

The antenna's electrical components and circuits were printed using nanoparticle "ink" on paper and a flexible polymer.

"We can now print circuits that are capable of functioning at up to 15 GHz — 60 GHz if we print on a polymer," said Rushi Vyas, a graduate student working on the project.

At present, the antenna can capture the stray energy of radio signals ranging from FM to radar. Once it harvests the energy, it converts it from AC to DC and then stores it on a battery.

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The scavenging device could also piggy-back with other energy-generating technologies like solar cells. During the day, the solar cells could be gathering energy from the sun, while the antenna is harvesting ambient electromagnetic energy. At night, when the sun goes down, the antenna can continue to work, thereby increasing the overall power output of the solar cells.

The researchers anticipate the autonomous, paper-based wireless sensors will not only be available soon, but will also be affordable.  

Credit: Georgia Tech, Gary Meek