Charging your laptop or mobile phone through a tangle of cables and plugs could soon be a thing of the past, thanks to physicists at the Massachusetts Institute of Technology, who have come up with a new way to power electronic gadgets without an electrical cable.
Marin Soljacic and colleagues have devised a wireless technique that uses an electromagnetic field to transfer energy from a power source to a device several metres away.
Today's wireless transfer of energy, such as the transfer of light energy from the Sun for solar power or the transfer of microwaves from transmitters for communication, involve relatively low levels of energy.
But recharging devices like laptops requires a much higher level of energy, and if this much amount of energy was transferred through the air it could burn any living organisms that get in the way.
However the team claims to have found a way of transmitting energy so that only the devices that it is recharging will pick it up, so it will not affect the surroundings.
Instead of irradiating the environment with electromagnetic waves, a power transmitter would fill the space around it with a "non-radiative" electromagnetic field. Energy would only be picked up by gadgets specially designed to "resonate" with the field. Most of the energy not picked up by a receiver would be reabsorbed by the emitter.
With the proposed designs, non-radiative wireless power would have limited range, and the range would be shorter for smaller-size receivers. But the team calculates that an object the size of a laptop could be recharged within a few meters of the power source. Placing one source in each room could provide coverage throughout your home.
Soljacic is looking forward to a future when laptops and cell phones might never need any wires at all.
He says that the system, could also power other household gadgets that are now becoming more common.
"At home, I have one of those robotic vacuum cleaners that clean your floors automatically," he said, "it does a fantastic job but, after it cleans one or two rooms, the battery dies."
