Spin-Coated Nanowire-Polymer Electrolyte for Low-Latency Humidity Sensing in CO2 Atmospheres

Kurzfassung

Previous studies have demonstrated the efficacy of SiO2 composite ionic liquid gel polymer electrolyte (SiO2-CILGPE)-based capacitors as relative humidity (RH) sensors. These devices exhibit stable and unaltered electrical behaviours, specifically in their impedance module and phase, under both air and CO2 atmospheres, confirming their viability for planetary research applications such as Mars habitability studies. However, a critical limitation of the initial prototypes was their slow stabilization and response time. This was primarily attributed to the drop-casting fabrication method, which resulted in a relatively thick sensing layer of approximately 600 µm. To address this challenge, this work presents a refined fabrication technique utilizing spin coating to achieve a significantly thinner active layer. Furthermore, Al2O3 (alumina) nanowires have been incorporated into the polymer matrix. The primary purpose of this study is to evaluate, via electrochemical impedance spectroscopy (EIS), a technique chosen for its capability to comprehensively decouple the resistive and capacitive dynamics within the sensing layer, how this new composite and deposition method accelerates the sensor's dynamic response to humidity variations in controlled CO2 environments, overcoming the previous latency issues without compromising its established stability.