Ultrasonic Networking for e-Health Applications

Wirelessly networked systems of intra-bodysensors and actuators could enable revolutionaryapplications at the intersection between biomedicalscience, networking, and control with astrong potential to advance medical treatment ofmajor diseases of our times. Yet, most researchto date has focused on communications along thebody surface among devices interconnectedthrough traditional electromagnetic radio-frequency(RF) carrier waves; while the underlyingroot challenge of enabling networked intra-bodyminiaturized sensors and actuators that communicatethrough body tissues is substantially unaddressed.The main obstacle to enabling thisvision of networked implantable devices is posedby the physical nature of propagation in thehuman body. The human body is composed primarily(65 percent) of water, a medium throughwhich RF electromagnetic waves do not easilypropagate, even at relatively low frequencies.Therefore, in this article we take a different perspectiveand propose to investigate and study theuse of ultrasonic waves to wirelessly internetworkintra-body devices. We discuss the fundamentalsof ultrasonic propagation in tissues, andexplore important tradeoffs, including the choiceof a transmission frequency, transmission power,and transducer size. Then, we discuss futureresearch challenges for ultrasonic networking ofintra-body devices at the physical, medium accessand network layers of the protocol stack.