Magnetic Fields Forever

Signals sent through the body could be the future of wireless.


Just when Bluetooth looked like the ticket to a wireless lifestyle, the power of magnets could make it a thing of the past.

Electrical engineers at UC San Diego recently demonstrated a technique that sends low-power magnetic fields through the human body, proving a concept that could one day enable better communication between wearable gadgets, such as a smart watch or fitness wristband.

Web - Patrick Mercier UCSD
Patrick Mercier, co-director of the Center for Wearable Sensors and affiliate of the Center for Wireless Communications

The technology came from the lab of Professor Patrick Mercier, co-director of the Center for Wearable Sensors and affiliate of the Center for Wireless Communications. Mercier says the method could yield a lower power and more secure alternative to current Bluetooth wireless technology.

Most mobile and wearable devices transmit information wirelessly using Bluetooth radios, which work well when communicating over short distances—until a body stands in the way. Since Bluetooth radio signals don’t travel easily through biological tissues, they require a battery-draining power boost to overcome the obstruction. On the other hand, magnetic fields travel freely through biological tissues, allowing signals to be communicated with little interference.

To demonstrate magnetic field human body communication, Mercier and his team wrapped insulated coils of copper wire around the head, arms and legs of one of their lab members. They then ran an electric current through the coils to produce magnetic fields and measured how well magnetic signals transmitted from one part of the body to another: arm to arm, arm to head and arm to leg. They found that the signal losses were as much as 10 million times lower than those using Bluetooth.

“This technique will allow us to build much lower power wearable devices,” says Mercier, who also believes that magnetic communication through the body could provide more security than Bluetooth networks, which are vulnerable to hacking because they transmit data over the air.

For those worried about potential health risks associated with passing magnetic signals through their bodies, Mercier also points out that the technique transmits signals much weaker than those produced by the Earth’s natural magnetic field. The work is still a proof-of-concept demonstration, yet researchers envision developing the technology for applications such as wireless sensor networks that could one day allow for full-body health monitoring.