Polar solvent-enhanced PEDOT:PSS-based elastomer as a self-healing film for strain sensing and human motion monitoring

The rising demand for wearable electronics has accelerated the development of flexible and biocompatible strain sensors that can conform closely to the human skin. While poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is a promising material due to its processability, conductivity, and biocompatibility, the inherent brittleness and limited stretchability significantly restrict its application in flexible electronics. Although previous approaches and additives have been explored to enhance its mechanical properties, many raise concerns regarding skin discomfort and toxicity. In this study, we report a flexible strain sensor based on PEDOT:PSS modified with a polar solvent system, which simultaneously improves conductivity, mechanical properties, and self-healing capability at room temperature. The resulting sensor demonstrates excellent biocompatibility, skin-like mechanical flexibility, and strong strain sensitivity. It is capable of detecting both small and large human motions, including facial expressions and joint movements, making it highly suitable for applications in advanced wearable electronics and long-term health monitoring.