One of the key problems with wearable electronics continues to be battery capacity, and while packing a larger battery into a small device may address the issue, it also makes the device less fashionable and therefore, less marketable. At least one company has built a prototype using Wi-Fi signals to charge devices up to 15 feet away, but uBeam, a US startup, uses a different method: sound.

The uBeam device is less than 5mm thick and uses ultrasound to charge other devices from anywhere in a room. Devices such as smartphones, tablets and wearables can be equipped with a thin receiver that takes the sound waves and converts them into usable electricity, charging the battery.

One significant drawback to the technology from which Wi-Fi-based technologies do not suffer is that sound waves cannot effectively penetrate walls. On the other hand, the range of the technology is far greater than that of a Wi-Fi based charging system and could conceivably be used in large, outdoor spaces.

While it remains to be seen if the device is commercially feasible (only a single working prototype has been made), the basic concept has been proven to work.

The company expects to have commercial products within two years, and it has two types of products targeted at different markets: smaller versions for homes and offices, and devices for larger spaces like stadiums, parks, airports and other public venues.

See a comparison table of wireless charging device manufacturers on GlobalSources.com