Long-term stability of electrochemical gas sensors based on capillary forces of electrolyte in porous glass material

Abstract

Electrochemical gas sensors typically use liquid sulfuric acid electrolytes, prone to evaporation and leakage, degrading performance and limiting lifespan. A porous glass membrane (PGM) was infused with an aqueous sulfuric acid solution to address this. The PGM's porous structure enables capillary action, reducing the exposed surface area of the electrolyte and stabilizing its retention. This capillary-driven mechanism significantly decreases evaporation, enhancing the sensor's long-term stability. In a laminated structure, PGM is an electrolyte reservoir, while a glass microfiber filter (GMF) is a separator and electrolyte supplier. Maintaining equilibrium in electrolyte distribution between these layers ensures consistent gas reaction performance. At 60 °C and 10 ± 5 % RH, the PGM sensor demonstrated a reduced evaporation rate of 3.1 %, compared to 7.1 % for conventional sensors. This study confirms that the capillary effect of PGM effectively minimizes electrolyte evaporation, extends sensor lifespan, and ensures stable sensitivity under extreme conditions.