Systematic Benchmarking of a Noise-Tolerant Conductive Hydrogel Electrode for Epidermal Bioelectronics

This study systematically benchmarks a crosslinker-free PEDOT:PSS-based conductive hydrogel electrode designed to overcome signal instability, motion artifacts, and impedance variability common in epidermal bioelectronic interfaces. Two formulations—PPSCF and PPHG—were fabricated using a gelatin–chitosan–glycerol matrix to promote mixed ionic–electronic conduction and enhance skin conformity. Through physicochemical characterization, dielectric spectroscopy, and long-term stability testing, the optimized PPHG hydrogel demonstrated superior electrochemical capacitance, high mechanical compliance, and stable performance under diverse environmental and physiological conditions. Human-subject testing across 39 participants revealed that PPHG consistently improved surface electrophysiology recordings (ECG, EEG, EMG, EOG), yielding enhanced signal-to-noise ratio, reduced motion artifacts, and improved extraction of clinically relevant features compared to Ag/AgCl electrodes. The work establishes a sustainable, reusable hydrogel electrode with robust electromechanical coupling suited for next-generation wearable biosensing.