What if your smartphone or laptop started charging as soon as you walked in the door? Researchers have developed a specially built room that can transmit energy to a variety of electronic devices within it, charging phones and powering home appliances without plugs or batteries.

This system “enables safe and high-power wireless power transfer in large volumes,” says Takuya Sasatani, a project assistant professor at the University of Tokyo’s Graduate School of Engineering and lead author of the new study, which was published this week in Nature Electronics. The room relies on the same phenomenon as short-range wireless phone chargers: a metal coil, placed in a magnetic field, will produce an electric current.

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