Gamma irradiation effect on the structural, morphology and electrical properties of ZnO–CuO doped PVA nanocomposite thin films for Escherichia coli sensor

Abstract

Gamma irradiation effect on fabricated ZnO–CuO doped PVA nanocomposite thin films for determination of Escherichia coli has been investigated. Thin films of ZnO–CuO doped PVA were exposed to 60Co γ-radiation source at difference dose rate, ranging from 0 to 30kGy at room temperature. The structural, morphological and electrical properties of the sample were investigated using X-ray diffraction (XRD), Atomic force microscopy (AFM), UV–visible spectroscopy and Current–voltage (I–V) measurement. The X-ray diffraction (XRD) spectra have been performed to observe the formation of crystal phases of all pure ZnO–CuO thin films. The diffraction patterns reveal good crystalline quality. The surface roughness of the thin films which can be determined by conductive Atomic force microscopy (AFM) measurement became smoother as the gamma radiation increased. The optical absorption property has been determined by UV–visible Spectroscopy in the wavelength range of 300–800nm which indicate the energy gap, Eg increases from 2.70 to 3.80eV as the γ-radiation increased. The presence of E. coli as a bacterial contamination in water was identified by measuring the changes of conductivity of thin films using current–voltage (I–V) measurement. The sensitivity of the sensors has been observed to be higher at a higher radiation dose.