Printable, adhesive, and self-healing dry epidermal electrodes based on PEDOT:PSS and polyurethane diol

Abstract

Abstract Printable, self-healing, stretchable, and conductive materials have tremendous potential for the fabrication of advanced electronic devices. Poly(3,4-ethylenedioxithiopene) doped with polystyrene sulfonate (PEDOT:PSS) has been the focus of extensive research due to its tunable electrical and mechanical properties. Owing to its solution-processability and self-healing ability, PEDOT:PSS is an excellent candidate for developing printable inks. In this study, we developed printable, stretchable, dry, lightly adhesive, and self-healing materials for biomedical applications. Polyurethane diol (PUD), polyethylene glycol (PEG), and sorbitol were investigated as additives for PEDOT:PSS. In this study, we identified an optimal printable mixture obtained by incorporating PUD into PEDOT:PSS, which improved both the mechanical and electrical properties. Based on our optimization, for the 5% PUD/PEDOT:PSS free-standing films, a conductivity of approximately 30 S/cm, stretchability of 40%, and Young’s modulus of 15 MPa were observed with a light adhesion of 0.03 N/cm. A low resistance change (< 20%) was achieved when the strain was increased to 30%. Excellent electrical stability under cyclic mechanical strain, biocompatibility, and 100% electrical self-healing were also observed. The potential biomedical applications of this mixture were demonstrated by using a printed epidermal electrode on a stretchable silicone substrate. The PUD/PEDOT:PSS electrodes displayed a skin-electrode impedance similar to commercially available electrodes, and successfully captured physiological signals. This study contributes to the development of improved customization and enhanced mechanical durability of soft electronic materials.