Real-time Iinterdigitated Electrode-based Sensing of VOCs at Room Temperature and Analysis

The paper includes sensing of Volatile Organic Compound (VOC) such as Ethanol, Methanol, Isopropyl alcohol(IPA) and the fabrication of a real-time gas sensor for VOC sensing at room temperature (~27°C) based on Carbon nanotube/Zinc oxide (CNT/ZnO) nanofibers using printed circuit board (PCB) technology. The process started by fabricating a copper-based interdigitated electrode (IDE) sensor on a copper-clad laminate, and then CNT/ZnO nanofibers were drop-casted on the IDEs and rested for overnight incubation. For the synthesization of Cnt-ZnO nanofibers, electrospinning technique is used which is responsible for creation of an IDE-based chemo-resistive gas sensor. The usual adsorption switching property due to "p to n" type characteristic helps in VOC detection at operating temperature (150°C). With ZnO being dominant at high temperatures (more than 150°C) and CNT being dominant at low temperatures (less than 150 °C), the CNT/ZnO nanofiber is especially adept at performing as a dual-mode sensor. This is true even when adsorption switching is used. This study focused on sensing at room temperature. The experiments were conducted using 3 IDE sensors to validate the sensitivity and repeatability of the proposed approach at room temperature. The developed sensor can be employed to detect a minute fraction of organic compounds like ethanol, methanol, and isopropyl alcohol with a change in resistance of 172-271 kΩ, 298-325 kΩ, and 383-415 kΩ and the highest detection sensitivity of 54.35%, 57.90%, and 60.55%, respectively which is the critical range in industrial air quality monitoring & safety control systems to avoid asphyxia and explosion.