Highly sensitive ammonia sensor for diagnostic purpose using reduced graphene oxide and conductive polymer

In this study, we fabricate ammonia sensors based on hybrid thin films of reduced graphene oxide (RGO) and conducting polymers using the Langmuir-Schaefer (LS) technique. The RGO is first prepared using hydrazine (Hy) and/or pyrrole (Py) as the reducing agents, and the resulting pyrrole-reduced RGO (Py-RGO) is then hybridized with polyaniline (PANI) and/or polypyrrole (PPy) by in-situ polymerization. The four different thin films of Hy-RGO, Py-RGO, Py-RGO/PANI, and Py-RGO/PPy are deposited on interdigitated microelectrodes by the LS techniques, and their structures are characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results of ammonia sensing experiments indicate that the Py-RGO/PANI film exhibits the highest sensor response of these four films, and that it exhibits high reproducibility, high linearity of concentration dependency, and a very low detection limit (0.2 ppm) both in N₂ and exhaled air environments. The current gas sensor, therefore, has potential for diagnostic purposes because it has the additional advantages of facile fabrication, ease of use at room temperature, and portability compared to conventional high-sensitivity ammonia sensors.