Impedance variation with different relative humidities of PAni/Mn nanofibres

This paper presents the humidity sensing properties of surface-modified polyaniline (PAni). In this study, the impedance response and dielectric properties of pure- and doped-PAni have been investigated as a function of relative humidity (RH%) and frequency. PAni and PAni/Mn composite samples are synthesized by one-step interfacial polymerization process. The structural properties and surface morphologies of the prepared materials have been characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM), respectively. XRD confirms the formation of PAni and it shows semi-crystalline behaviour. FESEM shows granular, porous and well-distributed structure. It has been observed that the porosity and nanogranular structure increased with increasing doping percentage. Here, we observe that porous and granular structure of Mn-doped PAni shows better response and recovery time ( $${\sim }28\hbox { s}$$ ) and decreases in electrical impedance. Dielectric constants, dielectric loss and AC conductivity have also been discussed with variations in frequency and relative humidity.