Unexpected: A Sonar-Based Wireless Network that Lives in Your Body

Imagine your body colonized by devices that communicate using sonar.

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University of Buffalo

You’ve probably read about the future where we reengineer our bodies or seen it hyperbolized in film: people awash in bionic contrivances and bleeding-edge actuators, a melange of subcutaneous processors relaying wireless signals to each other and beyond, turning us into something like cyborg bio-routers swimming in a sea of continuous, real-time information.

Only there’s a problem with that: radio waves don’t propagate so well through skin and muscle, requiring significant energy to get the job done and generating a fair bit of heat in the process.

Researchers at the University of Buffalo are talking about an intriguing potential workaround that’s premised on an elementary school biology principle: the human body, with all its parts, amounts to roughly 60% water. What travels well through water? Sonic vibrations, of course, which is where sonar — sound propagation through water — comes in.

By designing sonar-based technology small enough to work within the confines of the human body (or worn without), the researchers hope to create sonar-based “body area networks” composed of interrelating ultrasonic sensors capable of generating or detecting wireless information and acting to treat diseases like diabetes or heart failure in real time.

We already use sound waves in medicine, of course. The most obvious example would be obstetric sonography (or as it’s more commonly known, an “ultrasound”), which allows obstetricians and expecting parents to visualize a child in the womb (using nondestructive sound waves). By contrast, my father once underwent a preemptive kidney stone procedure called a lithotripsy whereby destructive, high-energy shock waves were beamed through a target spot on his body to essentially pulverize the offending stones; the University of Buffalo researchers are obviously using the nondestructive type.

“This is a biomedical advancement that could revolutionize the way we care for people suffering from the major diseases of our time,” said Tommaso Melodia, an associate professor of electrical engineering with the university. Melodia is working off a five-year, $449,000 National Science Foundation CAREER grant and his research — begun in February 2013 and estimated to wrap in January 2018 — is titled “Towards Ultrasonic Networking for Implantable Biomedical Devices.”

According to Melodia:

[M]ost research to date has focused on communications along the body surface among devices interconnected through traditional electromagnetic radio-frequency (RF) waves; while the key challenge of enabling networked intra-body miniaturized sensors and actuators that communicate through body tissues is substantially unaddressed. The main obstacle to enabling this vision is posed by the physical nature of propagation in the human body, which is composed primarily of water, a medium through which RF electromagnetic waves do not easily propagate.

Melodia hopes to explore the fundamentals of ultrasonic networking as they relate to human tissue by using “a closed-loop combination of mathematical modeling, simulation, and experimental evaluation.” The goal: to create a “novel, safe and energy-efficient methods of communication between implanted medical devices and the outside world.”

Imagine medical tools like pacemakers, Holter monitors (as well as other biotelemetric instruments, say devices that track a body’s oxygenation levels) or blood glucose sensors with implantable insulin pumps (to monitor the blood and automatically regulate insulin dosing) communicating using ultrasounds instead of radio waves. Melodia suggests this sort of communication would be more efficient than electromagnetic radio waves.

“Think of how the Navy uses sonar to communicate between submarines and detect enemy ships,” he said. “It’s the same principle, only applied to ultrasonic sensors that are small enough to work together inside the human body and more effectively help treat diseases.”

Not mentioned in the research, but arguably of equal interest: How non-medical devices in a body area network (as well as our bodies, in terms of health safety) might benefit from sonar-based communication. Sonar-based subcutaneous smartphones, anyone?