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Bluetooth Alternative Communicates through Your Body

Researchers say magnetic signals sent through your body may be helpful to communicate data between wearable gadgets.
September 2, 2015

You communicate with your body all the time, but it may take on a very different meaning soon. Researchers at the University of California, San Diego, are in the early stages of developing technology that uses your body as a communication medium, which they say could eventually work as a lower power, more secure alternative to Bluetooth for wearable gadgets like smart watches and fitness and health trackers.

Patrick Mercier, an assistant professor at UCSD and co-director of its Center for Wearable Sensors, says that while the Bluetooth radios embedded in many gadgets are useful for transmitting data over short distances, they’re not that great at it when there’s a body in the way. That’s because we tend to absorb the radio signals Bluetooth depends on to move data from one device to another—which means more power has to be expended to communicate via Bluetooth to make up for it.

Magnetic fields can easily pass through the body, though. So in hopes of coming up with a way for the growing number of wearable gadgets to communicate without using as much of their already-limited batteries, Mercier and graduate student Jiwoong Park have been working on technology that they think can make it possible to communicate more efficiently by sending magnetic signals right through you.

Mercier and Park tried this out by wrapping insulated coils of copper wire around a person’s head, legs, and arms. A current was used to generate magnetic fields with the coils, and they measured how the magnetic waves were picked up by the other coils via the body.

The coils are “trying to use the arm as a guide, of sorts, to guide the magnetic wave across to the other side of the body,” Mercier says.

The researchers measured how much of the signal was lost from one body part to the next—arm to arm, or arm to head, for instance—and determined that it was as much as 10 million times less than what’s found with the use of Bluetooth. This leads them to think it could be used to make wearable gadgets that use way less power for communication.

Mercier thinks the technology is more secure than Bluetooth, since it’s using the body to transfer information rather than sending it over the air, making it harder to intercept any communications between devices. And he says the strength of the magnetic field they’re generating is “orders of magnitude” lower than, say, an MRI.

The technology is still just in the early prototype phase; Mercier says that while they have some “preliminary” prototypes that they’ve used to transfer brain activity data from a coil around the head to a coil around the wrist, and from there to a connected computer, it isn’t integrated into a wearable gadget yet. He adds that they’re also planning to do some experiments through which they’ll transfer something like the data from a heart-rate monitor across this sort of link to a smartwatch.

However, Mercier suspects the technology won’t be as useful for gadgets that don’t wrap around the body—like smartphones or a sensor-containing patch you might stick on your body—because they won’t propagate the magnetic waves through the body in the same way.

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