WiFi Could Provide Electricity, Charge Smartphone

John Lister's picture

A new gadget can turn WiFi signals into electricity. It could one day mean an end to charging phone batteries, though the power levels mean medical uses might be more realistic.

The device is a new variant of a "rectenna," which is short for rectifying antenna. Traditionally it turns electromagnetic energy into direct current electricity. Although the rectenna was developed more than 50 years ago, it's not been widely used.

At the moment the most common use is in contactless cards, where a wireless signal from a card reader can not only open communications, but provide just enough power to operate the electrical chip in the card.

Concept Works But Needs Improvement

The new variant of the rectenna is just a few atoms thick.

It turns wireless signals into alternating current, which is then converted to a direct current. In tests where the researchers exposed the rectenna to a typical WiFi signal of around 150 microwatts, the device was able to generate electricity with around 40 microwatts of power. (Source: independent.co.uk)

That's not exactly a huge among of power, but could operate some silicon chips and light up a basic display. To put it in context, you'd need somewhere between 13,000 and 65,000 times as much power to charge the average smartphone battery.

At this stage it's more a case of proving the principle rather than having a genuinely useful device. The researchers say they can develop the rectenna to be more sophisticated and efficient.

Medical Uses Could Be Key

While charging devices such as phones is an obvious use for the technology, it could be more useful for low-power devices where wireless charging is necessary. One example is in medical implants where small batteries may leak; in this case consequences would be very serious. (Source: theiet.org)

It could also be useful for developing "smart pills." These aren't actually medicine but instead are tiny pill-sized devices which pass through the body and collect medical data on the way.

What's Your Opinion?

Is it worth a lot of effort to develop phones that can charge by harnessing wireless signals? Would you be prepared to pay extra for a mobile device that didn't need recharging? Are the medical uses more important to explore?

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gmthomas44_4203's picture

Nikola Tesla where are your research notes??

supernovatj_10151's picture

So...If the Sun decides to send a huge Coronal Mass Ejection our way and knock out our Tel sats putting wifi signals (or any EM signals for that matter) out of commission, people with electronic implants with this tech will know they're gonna die soon. That thought alone will produce anxiety and eventually a stroke before the batteries run out. Just my $.02

lars.raiha_11848's picture

What seems to be easily forgotten is the fact that this one device charging would probably use up all the power of the wifi-transmission, in other words no wifi for the rest of the devices in proximity. Charging without cables of this type would probably need its own frequency band, there aren´t many available anymore...