Soft and Conductive Polyethylene Glycol Hydrogel Electrodes for Electrocardiogram Monitoring

The measurement of biosignals in the clinical and healthcare fields is fundamental; however, conventional electrodes pose challenges such as incomplete skin contact and skin-related issues, hindering accurate biosignal measurement. To address these challenges, conductive hydrogels, which are valuable owing to their biocompatibility and flexibility, have been widely developed and explored for electrode applications. In this study, we fabricated a conductive hydrogel by mixing polyethylene glycol diacrylate (PEGDA) with poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) polymers dissolved in deionized water, followed by light-triggered crosslinking. Notably, this study pioneered the use of a PEGDA-PEDOT:PSS hydrogel for electrocardiogram (ECG) monitoring- a type of biosignal. The resulting PEGDA-PEDOT:PSS hydrogel demonstrated remarkable conductivity while closely approximating the modulus of skin elasticity. Additionally, it demonstrated biocompatibility and a high signal-to-noise ratio in the waveforms. This study confirmed the exceptional suitability of the PEGDA-PEDOT:PSS hydrogel for accurate biosignal measurements with potential applications in various wearable devices designed for biosignal monitoring.