A Physics-Based Channel-Level Human Twin for Galvanic-Coupling Wearable Communication Links

This paper presents a physics-based characterization of wearable galvanic-coupling (GC) channels under narrow-band and wideband operation. A calibrated channel-level human twin maps anatomical properties, propagation geometry, and electrode–skin interface conditions into complex transfer functions for communication-system analysis. Attenuation, phase delay, and group delay are characterized for longitudinal and radial configurations, while bandwidth-dependent dispersion is quantified through attenuation ripple and delay-variability metrics. The framework is validated by in-vivo measurements below approximately 100 kHz, whereas the extension to 1 MHz is presented as a physics-based prediction of the calibrated electro–quasistatic finite-element model. Results indicate weakly dispersive electro–quasistatic behavior across the considered band. Propagation geometry primarily determines attenuation and baseline delay, whereas increasing bandwidth amplifies attenuation ripple and delay variability, tightening synchronization and equalization requirements. Ag/AgCl electrodes with conductive gel and foam backing significantly improve amplitude and phase stability. Overall, the proposed framework provides an experimentally aligned channel representation that links tissue electromagnetics to waveform-level communication metrics, enabling informed bandwidth selection, interface optimization, and receiver design for wearable GC systems.