Bench Talk

Wireless charging has been less than a spectacular success. Competing (that is, incompatible) standards, a slow reception by smartphone manufacturers, and RF-inhibiting aluminum phone housings and protective cases have resulted in a slow adoption rate by consumers. However, while the prime players have been battling each other, two companies have come up with solutions that eliminate the need for the inductive coils, magnetic resonance, charging pads, and mats that are required by other techniques. Intrigued?

Both solutions transmit RF energy delivered by a base station to a product enabled with one of their receivers, which captures the energy, converts it to DC, and sends it to the device’s power management system. The first product is called WattUp™ from Energous Corp. that delivers a total of 10W to a single device or simultaneously to a dozen battery-operated devices. Specifically, it will deliver power to four devices at 4W each up to 5ft away, 2W up to 10ft away, and 1W at 10 to 15ft away.

Figure 1: WattUp delivers "meaningful power" that is completely untethered, with no pads or power cords. Image from Energeous.

WattUp operates in the 5.8-GHz unlicensed ISM band. Its software scans to find WattUp-enabled devices and using localization and beamforming, directs the energy to a small pocket of space around them. And yes, there’s also an Android or iOS app for WattUp that performs a variety of functions, one of which is locating WattUp charging stations when you’re away from your home or office.

There’s also Ossia, which although founded in 2008 kept its concept, technology called Cota, and first product called the Cota Wireless Charger under wraps until 2013. The receiver can handle up to 6W of energy and has demonstrated the ability to deliver 1W to an iPhone through two walls from 40 ft away. Although the company says it has successfully charged up to 32 devices at a time, its first offerings will probably charge only one, intelligently determining which device needs “topping up” the most.

The company’s goal was to use as much existing hardware in the end-user device as possible to minimize the impact of adding yet another feature, so it uses the existing silicon and antennas for Wi-Fi at 2.4 and 5 GHz, Bluetooth, or ZigBee. Ossia has even developed a Cota-enabled AA battery that will remain charged as long as it’s within range of the base station. The base station is a round enclosure that looks like a glowing Wi-Fi router and has thousands of tiny antennas forming an electronically-steered phased antenna array to direct the energy. Ossia hopes to have products available sometime later this year with a range up to 10ft and later introduce models that can blanket an entire home.