Comprehensive Survey of Galvanic Coupling and Alternative Intra-Body Communication Technologies

Fundamental understanding of the processes that affect the state and well being of the human body continues to be a challenging frontier. Recent technological developments point toward the possibility of implanting sensors inside the body, thus enabling in-situ data gathering and real-time actuation with the transmission of the sensed data to other implants as well as external computational clouds. This paper aims to survey and compare the existing methods for achieving intra-body communication (IBC) covering the methods of galvanic coupling (waveguide-based), capacitive coupling (electric field-based), ultrasound (acoustic-based) and magnetic resonant coupling (magnetic field-based). The performance of each method is evaluated in terms of its physical layer characteristics, including operating frequency range, attenuation effects within the body, channel modeling methods, power consumption, achievable data rates, communication distance, and safety limits under prolonged signal exposure. Based on this metric-driven study, we identify specific scenarios where one or more of these different IBC methods are better suited. For the specific case of galvanic coupling, we provide select system designs, experimental results from a custom-designed testbed and target applications that are more appropriate for this method of IBC. To the best of our knowledge, this is the first work that encapsulates the state of the art and current research trends for several different types of IBC solutions, a topic that promises to revolutionize the future of healthcare.