Computational Comparison of AC and DC Excitation for Long-Term Electrodermal Activity (EDA) Recording Across Electrode Materials.

Reliable long-term electrodermal activity (EDA) acquisition is limited by time-dependent electrochemical effects at the electrode-skin interface, particularly under direct current (DC) excitation. Although alternating current (AC) excitation is commonly proposed to reduce electrode polarization and baseline drift, its long-duration benefits have not been systematically validated. This work presents a simulation-based framework for directly comparing AC and DC exosomatic EDA acquisition circuits while accounting for electrode material-dependent polarization and dynamic interface behavior. An extended Randles cell model is combined with real physiological EDA recordings to dynamically modulate tissue resistance over a 26.6-hour simulation. Both excitation modes use identical constant-current Howland pump architectures, ensuring excitation modality is the sole experimental variable. Simulation results show that DC excitation leads to progressive baseline drift, amplitude compression, and material-dependent degradation of signal fidelity driven by cumulative electrode polarization. These effects intensify with increasing electrode polarization strength and substantially reduce long-term physiological interpretability. In contrast, AC excitation consistently preserves tonic and phasic EDA components, maintains baseline stability, and exhibits robust signal fidelity across all modeled electrode materials despite ongoing interface degradation. Quantitative comparisons against known physiological ground truth confirm lower error and reduced sensitivity to electrode properties for AC-based simulations. These findings provide controlled, long-duration evidence that AC excitation offers practical advantages over DC excitation for stable EDA acquisition in wearable and ambulatory monitoring systems.