Facile preparation and characterization of nanostructured ZnO/CuO composite thin film for sweat concentration sensing applications

This research presents the morphological, structural, optical characterization and sweat sensing response of ZnO/CuO nanocomposite thin films synthesized by the SILAR (Successive Ionic Layer Adsorption and Reaction) method. The particle and crystallite size were increased with increasing SILAR cycles. AFM studies showed that the increase in the number of SILAR cycles resulted a decrease in surface roughness from 60 nm to 23 nm. The optical band energy and transmittance of the nanocomposite thin films were determined from the UV–Vis. spectrum as well as Tauc's plot, which showed a decrease in the optical band energy (from 2.06 to 1.89) with the increase of film thickness. Human hydration level sensing of the nanocomposite ZnO/CuO thin films was investigated by artificial sweat application. It was observed that there was a monotonous increase with the sensing response with respect to the artificial sweat concentration.