Can Wi-Fi power wearables and the IoT?

Powering the proliferating number of devices in the home or on the body is an ongoing challenge for many companies and electronics manufacturers. Sensor packages that could monitor temperature in a home are useful but are typically tethered by a cord to the wall or require periodic battery replacement. Devices such as surveillance and home security systems can be placed virtually anywhere, so long as a wire connects them to an outlet. Wearables such as smart watches with bright color screens are wonderful until the small battery drains.

This has led to a great deal of research into wireless charging at a distance. While many wireless charging solutions have been proposed, none has been able to reliably charge devices over long distances, at least not in an economically feasible way. One team from the University of Washington, however, has had a breakthrough with a ubiquitous system found in most places with an internet connection: Wi-Fi.

In their experiment, the researchers were able to power a battery-free temperature sensor up to 20 feet away from a Wi-Fi router, as well as a camera 17 feet away. In addition, the team was able to recharge a Jawbone UP fitness tracker to about 42 percent battery life after about 2.5 hours, using only Wi-Fi signals to charge. In fact, one of the key points around the concept is the use of Wi-Fi routers in a shop or facility to charge wearables without the user having to do a thing. The technology also could conceivably be used to position sensors in range of a Wi-Fi router without requiring a plug or battery, making positioning of sensors much easier and efficient.

However, it's only a first step towards being able to power devices remotely. Po-WiFi, as the scientists call it, wasn't able to get enough energy to more power-hungry devices. Even the simple sensors and camera used in the study were not sufficiently powered to ditch cords or batteries completely if they are to run at an optimum level. The camera in particular was only able to take a still image every 35 seconds or so at a distance of 17 feet from the router. Powering devices further becomes even more difficult since the potential power transmission declines at an exponential, not linear, rate.

Nevertheless, the researchers were able to demonstrate the ability to power or recharge devices at a distance, and with more sophisticated methods - or more energy-efficient devices - Wi-Fi may yet become a viable way to power remote devices and sensors.

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