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

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.

Characterization and measurements

Keywords:

PEDOT:PSS, electrophysiology, printable electronics, stretchable bioelectronics, polyurethane.