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Author: search.filters.author.Pratontep, SirapatSubject: search.filters.subject.Gas sensor

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    Hybrid gas sensor based on platinum nanoparticles/poly(methyl methacrylate)-coated single-walled carbon nanotubes for dichloromethane detection with a high response magnitude
    (2016-05-01)
    Muangrat, Worawut
    ;
    Yordsri, Visittapong
    ;
    Maolanon, Rungroj
    ;
    Pratontep, Sirapat
    ;
    Porntheeraphat, Supanit
    A dichloromethane (DCM) sensor with a high response magnitude was successfully fabricated using the integration of single-walled carbon nanotubes (SWNTs), poly(methyl methacrylate) (PMMA) and platinum nanoparticles (Pt NPs). A pristine SWNT network was first formed by drop-casting onto printed circuit board (PCB) substrates. Next, PMMA was coated onto the pre-dropped SWNT network by spin coating using a PMMA-toluene solution, followed by the deposition of Pt NPs by electron-beam evaporation (hereafter referred to as Pt/PMMA/SWNT). The Pt/PMMA/SWNT enabled an approximately 69-fold improvement in DCM detection compared to pristine SWNT. The high response magnitude of the Pt/PMMA/SWNT was successfully achieved because of the incorporation of PMMA and Pt functions. Swelling of the PMMA matrix as a result of DCM adsorption leads to PMMA volume expansion, thereby increasing the SWNT-SWNT distance, which results in an increase in the resistance. Pt NPs promote the dissociation of DCM to CO, and consequently the CO oxidation on the Pt NPs catalyst and electron donation from Pt NPs to SWNTs, resulting in an increase in the resistance. Moreover, a linear relationship was obtained between the sensor response of the Pt/PMMA/SWNT and the concentration of DCM. These results suggest that the integration of SWNTs with PMMA and Pt NPs is a promising approach for improving DCM detection at room temperature.
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    An artificial nose based on M-porphyrin (M = Mg, Zn) thin film and optical spectroscopy
    (2011-12-01)
    Kladsomboon, Sumana
    ;
    Pratontep, Sirapat
    ;
    Puntheeranurak, Theeraporn
    ;
    Kerdcharoen, Teerakiat
    Artificial nose has recently become an emerging instrument for quality assurance in the food industry. These paper present the optical gas sensors based on Magnesium-5,10,15,20-tetra phenyl-porphyrin (MgTPP) and Zinc-5,10,15,20-tetra phenyl-porphyrin (ZnTPP) thin films and their application as an artificial nose. Based on the measurement of optical absorbance response using a general UV-Vis spectroscopy, this artificial nose was tested to discriminate various volatile organic compounds (VOCs) and Thai beverages. Atomic force microscopy (AFM) and X-rays diffraction (XRD) were used to confirm the polycrystalline structure of the sensing materials. Density functional theory (DFT) calculations reveal that MgTPP interacts more strongly with the VOCs than ZnTPP, especially with methanol. The classification results of VOCs and Thai beverage vapors using the principal component analysis indicate that both MgTPP and ZnTPP-based artificial noses can be an efficient tool for quality assurance of alcoholic beverages. Copyright © 2011 American Scientific Publishers All rights reserved.