Electrical engineers at the University of California San Diego have demonstrated a new wireless communication technique that works by sending magnetic signals through the human body. The new technology “could offer a lower power and more secure way to communicate information between wearable electronic devices,” the researchers say, “providing an improved alternative to existing wireless communication systems.”

The researchers have built a prototype to demonstrate the magnetic field human body communication technique that consists of copper wires insulated with PVC tubes. On one end the copper wires are hooked up to an external analyser and on the other end the wires are wrapped in coils around three areas of the body: the head, arms and legs.

“These coils serve as sources for magnetic fields and are able to send magnetic signals from one part of the body to another using the body as a guide,” the engineers say. “With this prototype, researchers were able to demonstrate and measure low path loss communication from arm to arm, from arm to head and from arm to leg.

“In order to reduce power consumption when transmitting and receiving information, wireless systems need to send signals that can easily travel from one side of the human body to another. Bluetooth technology uses electromagnetic radiation to transmit data. However, these radio signals do not easily pass through the human body and therefore require a power boost to help overcome this signal obstruction or ‘path loss.’

Bluetooth alternative

“An advantage of this system is that magnetic fields are able to pass freely through biological tissues, so signals are communicated with much lower path losses and, potentially, much lower power consumption. Researchers showed that the path losses associated with magnetic field human body communication are upwards of 10m times lower than those associated with Bluetooth radios.”

“Another potential advantage of magnetic field human body communication is that it could offer more security than Bluetooth networks,” the researchers add. “Because Bluetooth radio communicates data over the air, anyone standing within 30 feet can potentially eavesdrop on that communication link. Magnetic field human body communication employs the human body as a communication medium, making the communication link less vulnerable to eavesdropping.

“With this technique, researchers demonstrated that magnetic communication is strong on the body but dramatically decreases off the body. To put this in the context of a personal full-body wireless communication network, information would neither be radiated off the body nor be transmitted from one person to another.”

Reduced power consumption

“This technique, to our knowledge, achieves the lowest path losses out of any wireless human body communication system that’s been demonstrated so far,” says Patrick Mercier, professor in the department of electrical and computer engineering at the university who led the study. “This technique will allow us to build much lower power wearable devices.

“In the future, people are going to be wearing more electronics, such as smartwatches, fitness trackers and health monitors. Currently, these devices transmit information using Bluetooth radios, which use a lot of power to communicate. We’re trying to find new ways to communicate information around the human body that use much less power.”

“A problem with wearable devices like smartwatches is that they have short operating times because they are limited to using small batteries,” adds PhD student Jiwoong Park. “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.”

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