A highly stretchable, stable and sensitive PEDOT:PSS-P(HEMA-co-AA) hydrogel for strain sensors

As a crucial component of flexible electronic devices, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-based hydrogels for strain sensors have garnered extensive attention for their potential in the field of wearable sensors due to their inherent conductivity and flexibility. However, challenges such as poor mechanical strength, limited sensitivity, and poor durability have hindered the widespread application of PEDOT:PSS hydrogels in high-performance strain sensors. In this study, we develop a novel PEDOT:PSS-P(HEMA-co-AA) hydrogel that addresses common limitations in hydrogel applications, demonstrating remarkable stretchability, low hysteresis, and reliable conductivity. The hydrogel is synthesized using a semi-interpenetrating polymer network (SIPN) strategy, combining the linear conducting polymer PEDOT:PSS with a chemically cross-linked network based on 2-hydroxyethyl methacrylate (HEMA) and acrylic acid (AA). This hybrid structure notably contributes to the hydrogel's mechanical properties, achieving a stretchability of 195 %, while maintaining a rapid response time of 0.20 seconds and exceptional cyclic stability over 1000 cycles under 100 % strain. Moreover, the hydrogel demonstrates promising strain-sensing capabilities, positioning it as a strong candidate for future applications in wearable electronics and flexible sensors. The adoption of the SIPN strategy, along with the synergistic combination of PEDOT:PSS and P(HEMA-co-AA), paves a new pathway for enhancing the mechanical performance and sensing properties of hydrogels in strain-sensing technologies.