A Highly Sensitive and Reliable Humidity Sensor for Low-Water-Pressure Detection in a Vacuum Environment via PEDOT:PSS Films

Exploring extraterrestrial water resources has far-reaching significance for future human space resource utilization and base construction. Consequently, the development of effective sensing technologies for in situ water detection is a critical endeavor. This work presents a highly sensitive and reliable water molecules sensor based on poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS) films. The device demonstrates exceptional performance under high-vacuum conditions (1.0 × 10^–3Pa), achieving an extremely low detection limit of 0.02 Pa (148 μg/mL) and exhibiting outstanding reversibility, repeatability, and long-term stability. Furthermore, the sensor successfully underwent rigorous survivability tests designed to simulate the harsh conditions of space, showing no significant performance degradation. Meanwhile, through in situ film surface/thickness and spectroscopic analyses, a deeper understanding of the hydrogen-bond-based interactions between water molecules and PEDOT:PSS has been elucidated. This research provides valuable new insights and a promising platform for the development of advanced sensors aimed at detecting water on other planetary bodies.