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Breath analysis has emerged as one of the accurate diagnostic techniques, which can be used to correlate disease conditions with the abnormal concentrations of certain biomarkers present in the exhaled breath. In this background, thin film based chemi-resistive Cerium-doped ZnO sensors were developed for detecting acetone and ethanolamine, which are the notable biomarkers of diabetes mellitus and carcinoma respectively. Ce-doped ZnO thin films were deposited on glass substrates using spray pyrolysis technique. X-ray diffraction patterns confirmed the formation of Ce-doped ZnO thin films with polycrystalline hexagonal wurtzite structure. Scanning electron micrographs and optical absorption spectra of Ce-doped ZnO thin films revealed the decrease in average grain size and increase in band gap respectively with an increase in Ce-dopant concentration. ZnO films with 0.004 and 0.008 M of Ce-dopant concentrations showed a better room temperature sensing response towards acetone and ethanolamine respectively. Highly selective nature of the developed sensing elements towards acetone and ethanolamine with swift response and recovery times can be considered as a non-invasive and cost effective method for the detection of diseases like diabetes mellitus and carcinoma. [ABSTRACT FROM AUTHOR]

Abstract: Undoped and nickel (Ni)-doped ZnO thin films were spray deposited on glass substrates at 523K using 0.1M of zinc acetate dihydrate and 0.002–0.01M of nickel acetate tetrahydrate precursor solutions and subsequently annealed at 723K. The effect of Ni doping in the structural, morphological, optical and electrical properties of nanostructured ZnO thin film was investigated using X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), UV–vis Spectrophotometer and an Electrometer respectively. XRD patterns confirmed the polycrystalline nature of ZnO thin film with hexagonal wurtzite crystal structure and highly oriented along (002) plane. The crystallite size was found to be increased in the range of 15–31nm as dopant concentration increased. The SEM image revealed the uniformly distributed compact spherical grains and denser in the case of doped ZnO thin films. All the films were highly transparent with average transmittance of 76%. The measured optical band gap was found to be varied from 3.21 to 3.09eV. The influence of Ni doping in the room temperature ethanol sensing characteristics has also been reported. [Copyright &y& Elsevier]

Highlights: [•] Undoped and Fe-doped ZnO thin films were spray deposited on glass substrates. [•] Morphology transition from nanospheres to nanorods was observed while doping Fe. [•] Grain size was increased with increase in Fe dopant concentration. [•] Optical band gap was decreased with increase in Fe dopant concentration. [•] Electrical conductivity of the doped film was increased with Fe concentration. [ABSTRACT FROM AUTHOR]