Magnetic signals can be used to communicate within the human body, a team of scientists recently said.
The newly developed technique sends magnetic fields through biological tissue and could be used for a human-hosted wireless sensor network. Full-body health monitoring might be an application.
The proof-of-concept idea, demonstrated recently by electrical engineers from the University of California, San Diego, could one day replace power-hungry Bluetooth for wearable networking, the researchers say.
It would also be more secure than existing communications between wearables, they reckon.
Signals move easier
Magnetic field-generating coils, wrapped around three parts of the body—head, arm, and leg—allowed signals to move easily from one side of the body to the other in the scientists' experiments.
This is unlike propagation with existing wireless communications systems, such as Bluetooth, which don't work well in-body. The problem with Bluetooth technology is that it uses inefficient electromagnetic radiation to transmit data.
Radio doesn't work
That electromagnetic radiation is what we now know as radio. And "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,'" the team said on the school's website.
The team presented their findings at this year's Annual International Conference of the IEEE Engineering in Medicine and Biology Society in Italy.
Power savings crucial
The kind of power boost you need to send any kind of radio signal is not a problem in itself, but anytime you need extra power for IoT devices, it adds bulk, along with maintenance issues—more recharging, battery replacement, and cost.
That maintenance adds up when you're working with large numbers of sensors. It's one reason why there's been a race for low-power chips. And hence the excitement over any low-power IoT tech.
"We're trying to find new ways to communicate information around the human body that use much less power," Patrick Mercier said on the website. Mercier is a professor in the Department of Electrical and Computer Engineering at UC San Diego.
Another benefit of what they call Magnetic Field Human Body Communication is that it might be more secure than Bluetooth networks.
"Because Bluetooth radio communicates data over the air, anyone standing within 30 feet can potentially eavesdrop on that communication link," the researchers say.
But, if the body is the "communications medium," it's less "vulnerable to eavesdropping. With this technique, the researchers demonstrated that magnetic communication is strong on the body but dramatically decreases off the body," they say.
"Increased privacy is desirable when you're using your wearable devices to transmit information about your health," Jiwoong Park, one of the students on the team and an author of the study, says.
No health risks
And what about the potential harm of magnetism racing through the human body? The researchers say that their system poses no health risks.
"The transmitting power of the magnetic signals sent through the body is expected to be many times lower than that of MRI scanners and wireless implant devices," they say on the website.
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