Flexible, Low-Cost, and Room Temperature Ammonia Sensor Based on Polypyrrole and Functionalized MWCNT Nanocomposites in Extreme Bending Conditions

We report a flexible and room temperature ammonia sensor based on polypyrrole/functionalized multiwalled carbon nanotubes (Ppy/f-MWCNTs). This nanocomposite has been synthesized by the in-situ chemical oxidative polymerization method and finally loaded on a transparent poly(vinylidene fluoride) (PVDF) membrane substrate. The entire flexible sensor fabrication process was cost-effective and easy to operate, making it ideal for commercial production on a wide scale. The optimized Ppy/f-MWCNT-based flexible sensor demonstrates improved sensing characteristics (26.5% for 100 ppm) with a low response time of 16 s and high response toward ammonia compared with pristine Ppy. In addition, high repeatability and long-term stability were also observed over a concentration range of 5-200 ppm. It shows high response toward ammonia among various gaseous analytes. Furthermore, the flexible sensor was mechanically robust and could produce a high response value even in extreme bending conditions. The flexible Ppy/f-MWCNT-based flexible sensors offer potential applications in advanced wearable devices to detect ammonia in the ambient environment.