Temperature Sensor based on Nano-Sized Zinc Oxide Synthesized via Drop wise Method

Nano-sized ZnO was synthesized through the hydroxide precipitation using drop wise method. The variations in resistance of sensing pellet at different temperatures were recorded. The relative resistance was decreased linearly with increasing temperatures over the range, 150°C-260°C. The activation energy of ZnO calculated from Arrhenius plot was found 0.007eV. Temperature response in terms of the relative variation, ∆R, of sensor resistance to a given temperature was measured. Sensing element has maximum average sensitivity 0.33%/°C to temperature. SEM and XRD of the sensing material were studied. Scanning electron micrographs show that synthesized zinc oxide is in the form of nanosheets. Minimum average thickness of ZnO nanosheets is found to be 35nm. Optical characterization of the sensing material was carried out by UV-visible spectrophotometer. By UV-Vis spectra, the estimated value of band gap of ZnO was found 4.59 eV.