Zn-doping to improve the hydration level sensing performance of CuO films

Abstract

Many previous works have reported the importance of hydration level monitoring especially during the high exercise activity in warm environments. Herein, we report the hydration level monitoring properties of the ZnxCu1−xO (x = 0, 0.05 and 0.1) nanostructures in the wide range of artificial sweat concentrations. Nanostructured CuO films were sequentially synthesized via the successive ionic layer adsorption and reaction (SILAR) method. The morphological, microstructural, optical, and sensing response of the produced samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), (UV–vis) spectrophotometer and current–voltage (I–V) measurements, respectively. XRD patterns of the films revealed that the mean crystallite size is decreasing from ~ 13.50 to ~ 11.03 nm with increasing Zn content. From UV–visible spectrum, it was determined that the optical energy band gap (Eg) of the films changes with the Zn content in the growth solution and it was in the range of (1.40–1.53) eV. A considerable improvement in hydration level sensing properties was noticed for 1 M% Zn-doped CuO films for all concentration levels. The results provide a new approach to fabricate high performance nanostructured metal oxide based hydration level monitoring devices.