Highly Sensitive Conductive Hydrogel Enabled by Nanoscale Synergy of Carboxylated MXene and Polypyrrole for Multifunctional Applications.

Conductive hydrogels are pivotal for flexible electronics. However, their sensitivity is often limited by the agglomeration and inefficient conductive network formation induced by the single-component nanofillers. To address these issues, we developed a nanoscale synergy strategy employing a hybrid filler system composed of two-dimensional carboxylated MXene (C-MXene) nanosheets and one-dimensional polypyrrole (PPy) chains within a polyacrylamide hydrogel. The C-MXene nanosheets formed a robust conductive scaffold that mitigates agglomeration, while the interwoven PPy chains bridge adjacent nanosheets, promoting efficient electron transport under strain and enhancing mechanical integrity. This synergistic interaction results in a hydrogel with an exceptional electrical conductivity of 5.5 mS/cm and a high strain sensitivity with a gauge factor of 7.52, enabling accurate monitoring of physiological movements. Leveraging the abundant binding sites provided by the carboxylated MXene and its inherent gas adsorption capability, we further extended this multifunctional platform to ammonia detection. These findings underscore that our nanoscale synergy strategy offers a powerful route to integrating multiple functionalities into a single, easily processable hydrogel platform.