A Cordless Future, Thanks to Wireless Electricity

The Haier prototype was powered by electricity converted from an oscillating magnetic field. The wireless transmission of electricity demonstrated so boldly in January at an international trade show may fulfill a quest that began more than a century ago by the inventor of alternating current himself, Nicola Tesla.

Wirelessly transmitted electricity was successfully created in 2005 by a team of physicists at MIT led by Professor Marin Soljacic. The company they founded, WiTricity Corporation, is now seeking original equipment manufacturers interested in licensing their method of transmitting power.

The WiTricity technology could loosely be described as "magnetic coupling." It involves two copper coils that are matched for magnetic resonance. One is connected to a power source (110-volt AC house current, for example) and is the "sender." The sender coil converts the electrical current to a non-radiating magnetic field that oscillates at a specific frequency and permeates the room. In order for the converted energy to be utilized, this oscillation frequency of the magnetic field must excite the matched coil housed within an electrical device, such as the TV on display at January's CES.

The idea of matched resonance of the coils would be akin to 100 wine glasses on a table, each with a slightly different amount of water so that each would vibrate at a unique frequency. An opera star who would sustain one note for a sufficient interval of time could eventually cause the one particular glass matching the frequency or pitch to resonate enough to shatter. In other words, the oscillation of the magnetic field would affect only the appliance equipped with the matching coil.

Other than establishing the oscillating magnetic field to resonate with and excite the specific receiver coil -- creating electrical energy for the appliance -- the magnetic energy field produced by the powered sender coil remains very close to its point of origin. Moreover, the WiTricity technology has a very weak effect on biological systems -- better known as people and pets.

The MIT scientists first demonstrated their successful strategy by illuminating a 60-watt bulb from 7 feet away, an accomplishment first reported in Science in July 2007. The MIT News noted then that Professor Soljacic was inspired to investigate wireless electrical power by being awakened by warning beeps emitted by his cell phone, which he had (once again) forgotten to plug in to recharge. As he looked at his wireless phone, he realized how much more convenient it would be if it could recharge on its own, wirelessly.

The wireless transmission of electrical energy is not a new idea. It was first explored by Nikola Tesla, the brilliant scientist who developed alternating current and the induction motor well over a century ago. Tesla proved the victor over Edison, who was a proponent of direct current for the generation of electrical power, in the so-called "current war." Finding a way to make the wireless transmission of electricity work over a distance greater than the diameter of the coils was at the heart of the problem, as was avoiding directed, intense and potentially harmful electromagnetic radiation. The scientists at MIT prevailed over these age-old problems.

The exhibition of the Haier television with WiTricity at the Las Vegas CES simply demonstrated the feasibility (or "proof of concept") for the wireless transmission of electricity. Nevertheless, Haier was honored with the Popular Science "Product of the Future" award for their efforts so far. The company remains committed to planning for the commercial production of efficient, wirelessly-powered appliances and devices as soon as possible.