Robust Polymeric Ionic Liquid/Ionic Liquid Solid-State Electrolyte Membrane for Miniaturized and High-Performance Electrochemical Gas Sensing

Room-temperature ionic liquids (RTILs), owing to their nonvolatility and excellent electrochemical properties, have emerged as promising alternatives to conventional aqueous electrolytes in electrochemical gas sensors. However, their intrinsic fluidity complicates device packaging and long-term stability, which significantly limits their applications. To overcome these challenges, this study introduced polymeric ionic liquid (PIL) into the ionic liquid (IL), solidifying it to form a robust membrane for miniaturized and high-performance electrochemical gas sensing. The hybrid electrolyte exhibits superior ionic conductivity, thermal stability, and electrochemical performance compared with conventional polymer-based electrolytes. The PIL/IL electrolyte was implemented on two typical planar sensor platforms: screen-printed electrodes for electrolyte formulation optimization and sensing validation, and flexible porous substrates (polyethylene terephthalate and polytetrafluoroethylene) with backside-permeable structures to facilitate gas diffusion and for sensing characterization. With hydrogen as the target analyte, the resulting sensors achieved excellent sensitivity, stability, and rapid response at room temperature. By developing a novel solid-state electrolyte and its integrated electrode architecture, this work establishes a scalable, easily fabricated strategy for high-performance, miniaturized electrochemical gas sensors with broad applicability.