Innovation

Bluetooth Alternative Uses Your Body's Magnetic Field To Transmit Signals

Magnetic fields
Your body's magnetic fields may one day replace Bluetooth. Jacobs School of Engineering, UC San Diego

Look at your wrist. If you’re like one of the millions of Americans with wearable technology attached to it — maybe a watch or a fitness tracker — then you’re well aware that it connects to your phone via Bluetooth. It’s the king of short-range wireless communication, but it has some drawbacks too. It works well when there’s a clear path from object to object, but it needs a significant power boost to push the signal through objects — this is known as "path loss." So how do we rid ourselves of path loss, all the while creating a more efficient and secure alternative to Bluetooth? A proof of concept from a team of researchers at the University of California, San Diego may be the answer.  

The new system works by sending data signals through your body’s natural magnetic field instead of over air waves. It doesn’t suffer from path loss because the human body is used as a transmission medium to send the signals between devices. For their prototype, researchers used PVC-wrapped wires tied to a user’s arm to generate magnetic fields that could transmit signals between different parts of the body.

“This technique, to our knowledge, achieves the lowest path losses out of any wireless human body communication system that’s been demonstrated so far. This technique will allow us to build much lower power wearable devices,” said lead author Patrick Mercier, a professor in the Department of Electrical and Computer Engineering at UC San Diego, in a press release.

Low power equals longer battery life, and extending battery life has been a challenge wearable makers have long faced. Products like the Fitbit fitness trackers need to be charged every 10 days or so, while the Apple Watch’s battery lasts the better part of a day before it needs recharging. “With this magnetic field human body communication system, we hope to significantly reduce power consumption as well as how frequently users need to recharge their devices,” said Jiwoong Park, a Ph.D. student and first author of the study.

If you’re thinking that using your body’s magnetic fields to send signals between devices is a good way to get cancer or another disease, fear not. The technique is intended for use in ultra-low-power communication systems, with a transmitting power that’s lower than an MRI machine or wireless implant device.

Security is another of the risks that Bluetooth faces, but with this new system, you won’t have to worry about anyone hacking your signal. Whereas Bluetooth allows anyone within a 30-foot radius to hack your signal, the researchers’ system gets drastically weaker as it gets further from the body’s magnetic field. This, in turn, makes it far less vulnerable to hacking.

Source: Mercier P, Park J, et al. 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, Milan, Italy. 2015.

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