Researchers Demonstrate a New, Easy Way to Charge Devices Wirelessly

At the University of Tokyo, a research team, headed by doctoral student Takuya Sasatani, the University of Michigan in the United States, and Disney Research, has successfully developed and demonstrated a room-wide device, which utilizes magnetic fields to charge compatible devices within it.

Device nodes can be around one-two-thousandth the size of the room charger itself. (Image credit: 2019 Sasatani et al.)

The internet of things is coming. People will soon find their environments populated by small sensors and other devices which need power and communication. We have a safe and elegant solution for this, and it too could help technology become more invisible.

Takuya Sasatani, Doctoral Student¸ Graduate School of Information Science and Technology, The University of Tokyo

The room-sized wireless power transfer system can concurrently charge numerous nodes—or devices—within the boundaries of a room. Electrical components and metal sheets are integrated into a column in the room’s center and also in the room’s structure itself. Since the system’s functional elements are embedded into a room, this kind of strategy is perfect for including in the latest buildings, albeit the researchers are also looking for means to retrofit prevalent environments.

In order to make the system to work, scientists leverage a phenomenon known as quasistatic cavity resonance. Here, oscillating magnetic fields restricted to a specific volume promote the flow of charge in devices that have uniquely designed coils. The magnetic field revolves around the room, with the electric field being confined to the components integrated into the core pole.

Safety is our prime concern and we will make sure that future deployments of our system meet all governmental regulations for health and safety. We use magnetic fields well within safety limits for human proximity and the electric field is isolated by capacitors in the central column. Conversely, the presence of people should not affect power transfer efficiency. It even plays well with Wi-Fi, though our system provides an alternative communication link with small power consumption. This can drastically extend battery life of the numerous low-power devices installed in our surroundings.

Takuya Sasatani, Doctoral Student¸ Graduate School of Information Science and Technology, The University of Tokyo

An important trait of devices, like sensors, is that they can convey their data from time to time. The scientists have designed a way that allows compatible devices to receive and send data via the same mechanism which drives them. To interact with the central system at several kilobits per second, compatible devices modulate a power signal in a way that is similar to the way an AM radio works. Despite the fact that it is yet to become suitable for streaming videos, the system is sufficient for communicating with numerous kinds of ambient data that are likely to be collected by sensors.

The combined power and data capacity of our system potentially makes it suitable for environments such as hospitals, greenhouses, labs, event spaces or your home. We will continue to innovate and improve power transfer loads and communication bandwidth, while ensuring compatible devices will be cheap and easy to manufacture.

Takuya Sasatani, Doctoral Student¸ Graduate School of Information Science and Technology, The University of Tokyo

In addition to being cost-effective to develop, the system should also prove economical to run, utilizing roughly 10 W of power, corresponding to an efficient LED light bulb.

Room-wide Wireless Power Transfer via Multimode Quasistatic Cavity Resonance

(Video credit: University of Tokyo)

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