Fabrication of a Moldable, Long-Term Stable, High-Performance Conductive Hydrogel Composed of Biocompatible Materials

The entire process of producing a conductive hydrogel for use as electrodes, such as in biomedical applications like electrocardiogram (ECG) and electromyogram (EMG), was conducted through a one-pot synthesis method where all reactions took place within a single reactor. In this study, the poly-(Hydroxyethyl methacrylate) (pHEMA)/Chitosan (CS) hydrogel was fabricated with improved functionality by incorporating phytic acid (PA). For a pHEMA hydrogel without PA, the functionality was 47.8%, while the pHEMA/CS/PA-200 hydrogel with 0.2 mL of PA exhibited a functionality of 67.8%, indicating an increase of approximately 20%. As the PA content increased to 0.025, 0.05, and 0.2 mL, the ionic conductivity also increased to 0.057, 0.14, and 1.5 S/m, respectively. Notably, the HCP-200 hydrogel showed a conductivity 104 4 times greater than the pHEMA hydrogel. Therefore, the HCP-200 hydrogel, among the three concentrations, was synthesized for further testing, including shaping and direct attachment to three electrodes for subsequent ECG and EMG signal analysis. In the case of ECG, the signal peak heights were similar for the existing electrodes, Ag/AgCl and HCP gel. The average value of the EMG signal peak height was approximately 4 times higher for HCP gel.