*2.3. Dielectric Constant (εr)*

Impedance measurements analysis can also provide data on the intrinsic dielectric constant and dielectric loss properties of an electrochemical sensor [39]. Dielectric studies are used to understand the mechanism of conduction and dielectric properties that may be valuable in developing a device's performance and in the design of the electronic devices. According to Ramesan and Santhi, who studied conducting polymer composites of polypyrrole (PPy) with different silver doped nickel oxide (Ag–NiO) nanocomposites, the dielectric constant was found to depend on the polarizability of dipoles in the direction of the applied field. From their results, they found that PPy exhibited a lower dielectric constant compared to all of the nanocomposites they studied [40]. Their argument was

supported by Anilkumar et al., who explained that the lower dielectric constant seen in conducting polymers may be attributed to the interfacial polarization of the composite materials. Interfacial polarization mainly arises from the electrical heterogeneities of the composite materials [41]. Strong interfacial interactions between the polymer and nanoparticles reduce the macromolecular chain's cohesive forces, which increases the dielectric constant of the composite. With further loading of the composites (>10 wt%) in the PPy matrix, it was found to decrease the dielectric constant. This is thought to be due to the formation of aggregates within the PPy matrix. They also found that the dielectric loss of composites is higher than that of PPy. The higher dielectric loss observed might be due to the high surface area, surface domain polarization and the quality of the electrical network formation [42]. With further loading of the composite, the dielectric loss was found to decrease. This may be due to the formation of clusters or discrete aggregates in the PPy matrix, which can prevent the migration of charge carriers through the polymer.
