Effect of Surface Morphology of Electro-spun EPAA Coatings on the H2S Sensing Performance of Corresponding Interdigitated Electrodes

In this article, the fabrication of interdigitated electrode (denoted by IDE) H2S sensor based on electroactive polyamic acid (denoted by EPAA) containing oligoaniline in the main chain is first demonstrated. First step involved the synthesis of amino-capped aniline trimer (denoted by ACAT). Subsequently, the EPAA and correspondent electroactive polyimide (EPI) was prepared by reacting ACAT and 4,4'-(4,4'-isopropylidene-diphenoxy)bis(phthliic anhydride (BSAA), followed by characterization. For the study of gas sensing, hydrophilic EPAA was found to show better sensitivity of H2S gas at the concentration of 50 ppm on IDE as compared to that of hydrophobic EPI. Therefore, as-prepared EPAA with higher gas sensitivity was chosen to process four distinctive morphological images (film, bead, bead-fiber, and fiber) on IDE through electro-spinning technique for following comparative studies in sensitivity, repeatability, response/recovery time and selectivity of H2S gas. The surface image of EPAA upon IDE exhibiting four distinctive morphologies was observed by SEM. The IDE with fiber morphology was found to show the shortest response time and longest recovery time of H2S gas as compared to other comparative counterparts. Moreover, IDE coated by four distinctive morphological images of EPAA was all show good repeatability of H2S gas sensing at specific concentration range.