Fabrication and Characterization of an Electrospun Polybenzimidazole–Carbon Nanotube Sensor for Volatile Vapor Detection

Research subject: In this study, a conductive sensitive layer composed of polybenzimidazole (PBI) and carbon nanotubes (CNTs) was designed and fabricated via electrospinning for the detection of volatile organic compounds (VOCs)—(methanol, ethanol, isopropyl alcohol (IPA), acetone—and water vapor.
Research approach: This study employed an experimental approach. In the first stage, various processing parameters—such as flow rate, voltage, and needle-to-collector distance—were optimized to enable the fabrication of uniform fibers with nanometric diameters. Subsequently, the fibers were deposited onto an interdigitated gold-on-glass electrode (IDE) as the sensor base to form the sensitive layer of the sensor. Finally, the dynamic response of the fabricated sensor was evaluated using a custom-built measurement system developed by the research group.
Main results: Optimal electrospinning conditions were established at a flow rate of 0.5 cc h⁻¹, an applied voltage of 24 kV, and a nozzle-to-collector distance of 15 cm, enabling the production of uniform nanofibers, as confirmed by scanning electron microscopy (SEM). Brunauer–Emmett–Teller (BET) analysis revealed a fiber specific surface area corresponding to 18.23 m² g⁻¹. Dynamic sensing experiments demonstrated strong sensor responses toward alcohols and acetone, with response intensity correlating inversely with alcohol polarity from methanol to IPA. The sensors exhibited an exceptionally short response time (< 10 s), attributed to the nanofibrous architecture of the sensing layer, which promotes rapid vapor diffusion and access to active sites. Furthermore, the response trends and selectivity toward target vapors were analyzed in the context of thermodynamic parameters, including the Flory–Huggins interaction parameter.