Making a wire-free future

WiTricity’s wireless charging technology is coming soon to mobile devices, electric cars, and more.

More than a century ago, engineer and inventor Nikola Tesla proposed a global system of wireless transmission of electricity — or wireless power. But one key obstacle to realizing this ambitious vision has always been the inefficiency of transferring power over long distances.

Near the end of the last decade, however, a team of MIT researchers led by Professor of Physics Marin Soljacic took definitive steps toward more practical wireless charging. First, in 2007, the team wirelessly lit a 60-watt light bulb from eight feet away using two large copper coils, with similarly tuned resonant frequencies, that transferred energy from one to the other over the magnetic field. Then, in 2010, they shrunk the coils down and significantly increased the efficiency of the system, noting future applications in consumer products.

Now, this “wireless electricity” (or “WiTricity”) technology — licensed through the researchers’ startup, WiTricity Corp. — is coming to mobile devices, electric vehicles, and potentially a host of other applications.

     The purpose

The aim is to forge toward a “wire-free world,” says Soljacic. Primarily, this means consumers need not carry wires and power bricks. But it could also lead to benefits such as smaller batteries and less hardware — which would lower costs for manufacturers and consumers.    

    The Witricity today

At present, WiTricity technology charges devices at around 6 to 12 inches with roughly 95 percent efficiency — 12 watts for mobile devices and up to 6.6 kilowatts for cars. But, with growing research and development, the company is increasing distance, scale, and efficiency. It’s also developed repeaters: passive devices that extend the distance of the power transfer. These can be developed into a wide variety of shapes and can be embedded in a carpet to “hop” the power across a room.