Cut the cord: ‘Charging room’ wirelessly powers electronics

Wireless technology allows users to tap into the internet and receive service without using cords. Imagine using wireless technologies to harness electricity that powers electronics without plugging them in. That’s the idea behind a collaborative project from University of Michigan and University of Tokyo researchers that uses magnetic fields to wirelessly charge devices.

The innovation

The researchers built a 10×10-foot aluminum “charging room” that has a conductive surface on room walls and a conductive pole to create magnetic fields. Electronic devices are equipped with wire coils to harness the magnetic fields in the room.

The system produces two separate 3D magnetic fields. One field circulates around the central pole, and the other spreads to the corners of the room to prevent charging dead zones.

The team put devices called lumped capacitors in the walls to generate a magnetic field that reaches throughout the room and traps dangerous electric fields within the capacitor.

The system wirelessly powered lamps, fans, and cell phones, and it shows promise for charging a multitude of other electronics. 

“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,” Alanson Sample, UM professor of computer science and engineering, said in a news release

The challenges

Other researchers have worked on wireless power systems, but they faced limitations. For example, the technology could either deliver a lot of power only over a short distance — even just a few millimeters — or provide very small amounts of power that travel longer distances. The UM researchers’ innovation reportedly is capable of producing significant amounts of power, 50 watts, that travel far enough to reach throughout an entire room.

Magnetic fields also tend to travel in circular patterns, so using them in a square room could create dead spots. Plus, receivers in an electronic device must align with the magnetic field in a specific way to grab and use the power to create a charge. 

“Drawing power over the air with a coil is a lot like catching butterflies with a net,” Sample said. “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.” 

Delivering a large, room-sized magnetic field while eliminating the technology’s inherent dangers is critical to making this concept work. The innovation must confine harmful electric fields that can heat up and harm living beings’ tissues. Previous projects used potentially harmful microwave radiation, or they required devices to be in contact with dedicated charging pads.

Advancing the concept

Testing on anatomical dummies indicates this technology could safely deliver at least 50 watts of electricity without exceeding FCC guidelines for electromagnetic energy exposure. The researchers believe they can achieve higher power levels that are still safe by making additional system improvements.

They’re currently setting up a system test in a University of Michigan building. A series of rooms in that building will be retrofitted with the equipment or have a new construction installation. They expect to complete the setup sometime this fall.

This innovation has the potential to scale to larger environments. The researchers say it will likely be several years before the technology is installed in commercial or residential buildings.

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