Tissue Safety Analysis and Duty Cycle Planning for Galvanic Coupled Intra-Body Communication

Abstract

Galvanic coupling is the enabler of closed-loop communication between implanted sensors and embedded actuating devices (such as drug injectors) by providing energy-efficient and reliable non-RF transmission through links formed within tissue. For safe deployment, it is critical to verify that the amount of heat generated within tissues during signal propagation stays within permissible bound. In this paper, we analyze the thermal distribution within tissues, for galvanic coupling-based communication for varying transmission power levels, number of collocated transmitters, and blood perfusion conditions using finite element based numerical simulation and skin-phantom based experiments. Our results confirm that tissue heating remains well below safe limit of 1 °C. Using the temperature dissipation profile, we derive the suitable transmission duty cycles, separation distances and number of concurrent sources that may co-exist without raising the tissue temperature. The proposed strategies provide up to four fold increase in bandwidth efficiency through concurrent transmissions, ensuring sufficient bandwidth for implant communications.