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University of Michigan researchers unveil wireless ‘charging room’ system that powers phones, laptops

U-M partnered with University of Tokyo for study

The finished charging room, located at The University of Tokyo.
The finished charging room, located at The University of Tokyo. (The University of Tokyo)

ANN ARBOR – Imagine a world with no charging cables that keep our devices tethered to power outlets.

Researchers at the University of Michigan and University of Tokyo have invented a system that they say safely delivers electricity through the air. Their vision? To potentially bring wireless charging zones to entire buildings.

Using magnetic fields, the new technology can transfer up to 50 watts of power, according to the study published in Nature Electronics.

Beyond our everyday electronics, the technology could also untether implanted medical devices and unlock the potential for mobile robotics in both manufacturing facilities and homes.

“This really ups the power of the ubiquitous computing world—you could put a computer in anything without ever having to worry about charging or plugging in,” said the study’s author and U-M professor of computer science and engineering, Alanson Sample, in a release.

“There are a lot of clinical applications as well; today’s heart implants, for example, require a wire that runs from the pump through the body to an external power supply. This could eliminate that, reducing the risk of infection and improving patients’ quality of life.”

The finished charging room, located at The University of Tokyo. (The University of Tokyo)

Guided by researchers at the University of Tokyo, the team utilized the technology in a 10 by 10-foot aluminum test room. There, they successfully charged fans, cell phones and lamps wirelessly regardless of where furniture was placed or where people stood.

The team says the system is a vast improvement over past attempts at wireless charging technology, which either used dedicated charging pads for devices or possibly toxic microwave radiation. The new technology creates magnetic fields by using a conductive pole and a conductive surface on walls in the room.

The magnetic field is then harnessed by devices with wire coils and is easy to scale up, researchers said.

“Something like this would be easiest to implement in new construction, but I think retrofits will be possible as well,” said researcher at the University of Tokyo and the corresponding author on the study, Takuya Sasatani, in a release.

“Some commercial buildings, for example, already have metal support poles, and it should be possible to spray a conductive surface onto walls, perhaps similar to how textured ceilings are done.”

Lumped capacitors set into wall cavities in the wireless charging room. (The University of Tokyo)

To avoid the release of harmful electric fields, the team used lumped capacitor devices placed inside wall cavities that trap electric fields while creating a magnetic field that flows around the room.

Another challenge was to work around the circular patterns in which magnetic fields travel to make sure the entire square room was covered.

“Drawing power over the air with a coil is a lot like catching butterflies with a net,” Sample said in a release. “The trick is to have as many butterflies as possible swirling around the room in as many directions as possible. That way, you’ll catch butterflies no matter where your net is or which way it’s pointed.”

To achieve this, the system creates two individual 3D magnetic fields -- each of which cover different areas of the room to eliminate dead spots.

The team used anatomical dummies to test whether they could deliver at least 50 watts of power without surpassing guidelines for electromagnetic energy exposure set by the Federal Communications Commission.

Although initial observations look promising, implementation of the technology in residential or commercial buildings would likely take years.

Currently, work is underway to test the system in a University of Michigan building.


About the Author:

Meredith has worked for WDIV since August 2017 and was voted one of Washtenaw County's best journalists in 2019 by eCurrent's readers. She covers the community of Ann Arbor and has a Master's degree in International Broadcast Journalism from City University London, UK.