Enhanced and selective acetone sensing properties of SnO2-MWCNT nanocomposites: Promising materials for diabetes sensor

Achieving good sensitivity toward low ppm acetone with pronounced resolution is a challenging, yet very much required task for the development of breath analyzer to monitor diabetes in a non-invasive way. We were able to achieve high sensitivity, stability, ultrafast response toward sub-ppm acetone with a good resolution just by using MWCNTs as a substrate for nanocrystalline SnO2 prepared through a facile sol-gel technique. The composites were well characterized using XRD and TEM/HRTEM which revealed not only the structure and purity of the samples but also indicates the successful integration of MWCNT with SnO2 nanoparticles. The composite sensor showed much better performance at the lower temperature than pure SnO2. Enhancement of adsorption ability of SnO2 due to the addition of MWCNTs, and the difference between their work function, could be collectively responsible for the improvement of sensing activity. Besides, these nanocomposite sensors also showed much-reduced cross-sensitivity toward moisture, which is a major component of human exhale breath. This will be an extra-advantage of MWCNT incorporation for developing breath analyzer to monitor diabetes using SnO2 nano-composites based sensor. (C) 2016 Elsevier Ltd. All rights reserved

Synergistic effect of Pd and Sb incorporation on ethanol vapour detection of La doped tin oxide sensor

4 wt% La-doped SnO2 nanocrystalline powders impregnated with 0.5-1.5 wt% Pd were synthesized by a facile sol-gel method. The powders characterized through XRD, TEM, EDX as well as XPS analyses were used for the fabrication of sensors. 0.5 wt% Sb2O3 was incorporated in each case to reduce the resistance of sensors. The gas response studies revealed a large enhancement in low concentration (1-100 ppm) ethanol vapour sensing at comparatively lower operating temperature (300 A degrees C) on 1.0 wt% Pd incorporation. The response observed (86 %) for 10 ppm vapour was 16 % greater compared to 4 wt% La-doped SnO2 with improved response (2 s) and recovery (15 s) times. The high ethanol vapor response at comparatively lower operating temperature of this sensor is attributed to the combinatorial effect of alkalescence of SnO2 due to La-doping and widening of depleted region by spill-over process of PdO present on SnO2 surface

Synthesis, characterization and vapour sensing properties of nanosized ZnFe2O4

In recent years, there has been a renewed interest on spinel ferrites for their remarkable versatile applications. Among AFe(2)O(4), zinc ferrite (ZnFe2O4) has gained special importance due to its application in gas sensing, drug delivery and magnetic resonance imaging. Nanocrystalline powder of ZnFe2O4 with average size of 25-30 nm was synthesized using citrate-gel method. Thermogravimetric analysis and XRD confirmed the formation of nanocrystalline ZnFe2O4 at 400 degrees C. The band appearing below 700 cm(-1) in the FTIR spectrum confirmed the presence of Zn(Fe-O) group. Microstructural investigation was done on SEM and TEM. The response of ZnFe2O4 towards alcohol and acetone vapour at 350 degrees C was studied. The sample showed n-type conductivity with excellent vapour sensitivity

Ethanol sensing evaluation of sol-gel barium calcium ferrite

Hexaferrites are very attractive materials for high-frequency circuits and operating devices, nevertheless their use for sensing application is very rare. In the present work, BaCa2Fe16O27 hexaferrite was synthesized by a simple sol-gel technique. Structural and microstructural information have been obtained by X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The gas sensing performance of BaCa2Fe16O27 hexaferrite-based sensors was investigated for the detection of some common volatile organic compounds and gases like ethanol, acetone, methane and carbon monoxide. The results showed the sensors to exhibit high sensitivity, quick response/recovery and good reproducibility and stability towards 100 ppm ethanol. Moreover the sensors proved to be highly selective from measurements of cross sensitivity. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved

Nanocrystalline gallium ferrite: A novel material for sensing very low concentration of alcohol vapour

Nanocrystalline orthorhombic gallium ferrite (GFO) has been synthesized by a sol gel method. The synthesized powder has been characterized by TG/DTA, XRD, TEM, FTIR and nitrogen adsorption isotherm. In the present study we report an excellent ethanol vapour sensitivity of nanocrystalline GaFeO3 at concentrations down to 1 ppm making the sensors suitable for application in food industries. Interestingly in contrast to the market available consumers breath analyser based on tin dioxide, GaFeO3-based sensor is immune to moisture (present in breath) and acetone vapour (an interfacing agent for diabetics). Such gallium ferrite based sensors can be used to make potential interference free breath analyser for real-life applications. In addition, such sensors being highly selective and do not show any cross-sensitivity towards moisture, methanol and carbon monoxide like those based on tin dioxide. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved