Our cell phones have become such an essential part of our lives that it can sometimes be hard to leave them alone. Whether you are a casual smartphone user or a technology enthusiast, you would love your phone battery to last a little longer, isn’t it? Most of us plug in our mobile phones for charging before going to bed, but this could one day seem quaint – as wireless charging becomes more and more widespread as a method for powering our handheld devices.
In this context, researchers at the University of Michigan and the University of Tokyo have developed a system to safely deliver electricity over the air, potentially turning an entire room into wireless charging zones. The technology called multimode quasistatic cavity resonance can deliver 50 watts of power using magnetic fields, according to researchers.
The team’s solution used devices called lumped capacitors embedded in wall cavities, which themselves are made with conductive surfaces. They generate a three-dimensional magnetic field that resonates through the room while trapping electric fields inside the capacitors themselves.
The problem with previous wireless power systems was how to generate a magnetic field that reaches every corner of the room, as the magnetic fields tend to travel in circular patterns, creating dead spots in a square room. Also, the receiver needs to align with the field in a specific way to draw power.
The new system generates two separate, 3D magnetic fields – one of which travels in a circle around a copper pole in the center of the room, while the other swirls in the corners, traveling between adjacent walls. This helps eliminate dead spots, enabling devices to draw power from anywhere in the space. The devices harness the magnetic field with wire coils, which can be integrated into electronics like cell phones.
The team tested their wireless charging technology in a purpose-built aluminum test room measuring approximately 3m × 3m × 2m and found that the technology could deliver at least 50 watts of power to any location in the room without exceeding FCC guidelines for electromagnetic energy exposure. They wirelessly powered lamps, fans, and cell phones that could draw current from anywhere in the room regardless of the placement of people and furniture.
According to the researchers, the system is a major improvement over previous attempts at wireless charging systems, which used potentially harmful microwave radiation or required devices to be placed on dedicated charging pads. The researchers say the system could easily be scaled up to larger structures like factories or warehouses. They note that implementation of the system in commercial or residential settings is likely years away.