Ganesh Kumar Mani | SASTRA University (original) (raw)

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Papers by Ganesh Kumar Mani

The effect of substrate and annealing temperatures on the structural, morphological, optical and ... more The effect of substrate and annealing temperatures on the structural, morphological, optical and electrical properties of spray deposited copper oxide thin ﬁlms was investigated. The ﬁlms were deposited on glass substrates using 0.05 M of cupric acetate precursor at the substrate temperatures of 523, 623 and 723 K. From the structural, morphological and optical characteristics, the ﬁlm coated at 623 K was found to have better crystallinity with mixed cuprite and tenorite phases. Thus, substrate temperature was ﬁxed at 623 K and ﬁlms were prepared by increasing the molar concentration of cupric acetate to 0.1 M. Further the effect of annealing on the various properties of the CuO ﬁlms was investigated. The XRD patterns of the annealed ﬁlms at 523, 623 and 723 K for 6 h revealed the formation of copper oxide thin ﬁlms with tenorite phase.

Vanadium pentoxide (V2O5) thin films were deposited on glass substrates using spray pyrolysis tec... more Vanadium pentoxide (V2O5) thin films were deposited on glass substrates using spray pyrolysis technique. Aqueous solution of ammonium vanadate with 0.1 M concentration was used to deposit V2O5 thin films at different substrate temperatures. The structural, morphological, electrical, optical and vapour sensing properties of the films were investigated. XRD patterns confirmed the polycrystalline nature of the films with orthorhombic structure. Crystallite size was increased with an increase in the substrate temperature. SEM images showed the formation of films with flower like morphology. From the optical absorbance spectra, the optical band gap was determined and varied between 3.34 to 3.24 eV. The charge carrier concentration was found to be increased with substrate temperature. Room temperature xylene sensing characteristics of the films were investigated. The influence of substrate temperature on the vapour sensing characteristics of V2O5 is reported.

Strong electrophilic natured acetaldehyde present in various food and beverages damages genetic m... more Strong electrophilic natured acetaldehyde present in various food and beverages damages genetic material and induces diseases like atherosclerosis. Detection and quanti ﬁ cation of such a carcinogen poses a major challenge. In this context, a novel room temperature acetaldehyde sensor made up of hierarchical ZnO nanostructures and prepared by a simple and template-free method has been reported. ZnO nanostructures were grown on glass substrates by a chemical spray pyrolysis technique at the substrate temperature of 523 K. Di ﬀ erent nanostructures, namely tiny nanoplatelets, branched nanorods and thicker nanoplatelets, were formed by an annealing process. The crystal structures, morphologies and optical absorbances of the hierarchical ZnO nanostructures were investigated by X-ray di ﬀ raction (XRD), ﬁeld emission scanning electron microscopy (FE-SEM) and UV-vis spectrophotometry, respectively. The branched nanorods showed an excellent sensing response towards 20 to 500 ppm of acetaldehyde
vapour. The role of high density junctions of the branched ZnO architecture in enhancing the vapour sensing performance has been highlighted. The observed selectivity, range of detection and stability of the branched ZnO nanorods have proven their potential as a sensing element for the detection of acetaldehyde.

Ammonia sensing characteristics of undoped and cobalt (Co)-doped nanostructured ZnO thin films we... more Ammonia sensing characteristics of undoped and cobalt (Co)-doped nanostructured ZnO thin films were investigated. Polycrystalline nature with hexagonal wurtzite structure and high crystalline quality with dominant (002) plane orientation of Co-doped ZnO film were confirmed by the X-ray diffractogram. Scanning electron micrographs of the undoped film demonstrated the uniform deposition of sphere-shaped grains. But, smaller particles with no clear grain boundaries were observed for Co-doped ZnO thin film. Band gap values were found to be 3.26 eV and 3.22 eV for undoped and Co-doped ZnO thin films. Ammonia sensing characteristics of Co-doped ZnO film at room temperature were investigated in the concentration range of 15 to 1000 ppm. Variation in the sensing performances of Co-doped and pure ZnO thin films has been analyzed and compared.

A simple and cost effective spray pyrolysis technique was employed to deposit nanostructured ZnO ... more A simple and cost effective spray pyrolysis technique was employed to deposit nanostructured ZnO thin films at the substrate temperature of 523 K on glass substrates from the aqueous solution of zinc acetate dehydrate. The effect of various ratios of water and ethanol solvents on the structural, morphological, optical, electrical and sensing characteristics of ZnO film was investigated. X-ray diffraction patterns revealed the polycrystalline nature of the films with hexagonal wurtzite struc-ture. Morphology and grain size of the films were observed using Field Emission Scanning Elec-tron Microscope (FE-SEM). SEM images revealed the uniform distribution of the spherical grains particularly for the films prepared with ethanol as solvent. The optical absorbance spectra of the thin films were studied using UV-Vis spectrophotometer in the wavelength range of 300–800 nm which showed a sharp absorption edge with overall transmittance of more than 85%. The sensing performance of the thin films towards the volatile organic compounds (VOC's) like acetaldehyde, ethanol, ammonia, hydrogen peroxide, and ethanolamine (MEA) were studied and films showed better response towards MEA than others.

Undoped and manganese (Mn)-doped nanostructured ZnO thin films were deposited on glass ... more Undoped and manganese (Mn)-doped nanostructured ZnO thin films were deposited on glass substrates using spray pyrolysis technique at the substrate temperature of 523 K and subsequently annealed at 673 K for 3 h. The deposited films were found to be polycrystalline in nature with hexagonal wurtzite structure. The FE-SEM images showed the influence of Mn doping on the surface
morphology of the uniformly deposited ZnO nanograins. The transmittance of the film was found to be diminished as the concentration of Mn was increased. The room temperature sensing characteristics of the doped and undoped ZnO films were studied towards acetaldehyde, hexanol, ammonia, acetone, ethanol and monoethanolamine vapours. The results revealed that the sensing element was highly selective
towards ammonia vapour. High sensing response of 1250 was achieved for 0.008 M Mn-doped ZnO sample with the response and recovery time of 60 and 68 s respectively.

This paper provides a review of the most recent works in electronic noses used in the food indust... more This paper provides a review of the most recent works in electronic noses used in the food industry. Focus is placed on the applications within food quality monitoring that is, meat, milk, ﬁsh, tea, coffee and wines. This paper demonstrates that there is a strong commonality between the different application area in terms of the sensors used and the data processing algorithms applied. Further, this paper provides a critical outlook on the developments needed in this ﬁeld for transitioning from research platforms to industrial instruments applied in real contexts.