Propagation analysis of implantable human body communication system for neurostimulators and structural evaluation of abdominal models

This paper presents a propagation analysis of an implantable human body communication (IHBC) system for neurostimulators and a structural evaluation of simplified abdominal models. Modern medicine relies on implantable medical devices to provide advanced diagnostics and treatments for patients. Communication between such devices and external devices is crucial for tailored medical services but suffers from high power consumption due to signal attenuation within biological tissues. In addition, electromagnetic interference with surrounding devices and security risks caused by unauthorized wireless access are also concerns. To address these issues, we previously proposed an IHBC system that utilizes biological tissues as a transmission medium, employing low-frequency bands to minimize signal attenuation and external radiation. This study focuses on communication between a neurostimulator implanted in the lower abdomen and an external controller. Electromagnetic field analysis using an anatomically accurate human body model was performed to elucidate the signal propagation mechanisms, and the transmission characteristics were evaluated for various implant depths and positions. Moreover, we propose simplified abdominal models to reduce computational resource demands while maintaining analytical accuracy. Our findings suggest that a three-layer abdominal model, consisting of skin, fat, and muscle, achieves a balance between computational efficiency and accuracy, demonstrating close agreement with anatomical models. These results provide critical insights for the design of IHBC systems and their practical applications.