Wongwiriyapan, Winadda

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Preferred name
Wongwiriyapan, Winadda
Alternative Name
Wongwiriyapan, W.
Main Affiliation
Email
winadda.wo@kmitl.ac.th

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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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    Polymer-coated single-walled carbon nanotubes for ethanol and dichloromethane discrimination
    (2013-10-29)
    Muangrat, Worawut
    ;
    Maolanon, Rungroj
    ;
    Pratontep, Sirapat
    ;
    Porntheeraphat, Supanit
    ;
    Wongwiriyapan, Winadda
    Sensor response and pattern recognition of polymer-coated single-walled carbon nanotubes (SWNTs) were investigated. Printed circuit board (PCB) with Cu/Au interdigitated electrode was used as sensor platform. SWNTs network was firstly formed on PCB by drop-casting. For polymer-coated SWNTs preparation, poly(methyl methacrylate) (PMMA) and thiophene were employed as polymers to coat on SWNTs by spin coating; PMMA/SWNTs and thiophene/SWNTs. Raman spectra showed no obvious structure changes of SWNTs after polymer coating. Next, gas sensing test was conducted. Pristine SWNTs, PMMA/SWNTs and thiophene/SWNTs were exposed to vapors of ethanol and dichloromethane at room temperature. From normalized sensor response results, it was found that pristine SWNTs and PMMA/SWNTs showed the highest response to ethanol and dichloromethane vapors, respectively. In order to discriminate vapors between ethanol and dichloromethane, pattern recognition technique was utilized. Principal component analysis (PCA) results showed that pattern recognition of ethanol and dichloromethane vapors can be discriminated by using pristine SWNTs and polymer-coated SWNTs sensors. © (2013) Trans Tech Publications, Switzerland.
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    Poly(methyl methacrylate) and thiophene-coated single-walled carbon nanotubes for volatile organic compound discrimination
    (2016-02-01)
    Muangrat, Worawut
    ;
    Chodjarusawad, Thanawee
    ;
    Maolanon, Rungroj
    ;
    Pratontep, Sirapat
    ;
    Porntheeraphat, Supanit
    Poly(methyl methacrylate) (PMMA) and thiophene-coated single-walled carbon nanotubes (SWNTs) were fabricated for use in volatile organic compound (VOC) detection. Pristine SWNTs were separately coated with PMMA (PMMA/SWNTs) and thiophene (thiophene/SWNTs) by spincoating. Pristine SWNTs showed the highest response to methanol, while PMMA/SWNTs enabled 5.4-fold improved dichloromethane detection and thiophene/SWNTs enabled 1.4-fold improved acetone detection compared with pristine SWNTs. The sensor response of PMMA/SWNTs to dichloromethane and that of thiophene/SWNTs to acetone can be attributed to the Hildebrand solubility parameter (HSP). The more similar the HSP, the higher the sensor response. The sensor response of pristine SWNTs to methanol is related to the diffusion coefficient and molecular size. The relationships between the vapor concentration and sensor response of PMMA/SWNTs to dichloromethane and thiophene/SWNTs to acetone are based on Henry's adsorption isotherm, while that of pristine SWNTs to methanol is based on the Henry-clustering model. Principal component analysis (PCA) results show that dichloromethane, acetone, and methanol were successfully discriminated.
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    TiO2/Pt/TiO2 Sandwich Nanostructures: Towards Alcohol Sensing and UV Irradiation-Assisted Recovery
    (2017-01-01)
    Maolanon, Rungroj
    ;
    Wongwiriyapan, Winadda
    ;
    Pratontep, Sirapat
    The TiO<inf>2</inf>/Pt/TiO<inf>2</inf> sandwich nanostructures were synthesized by RF magnetron sputtering and demonstrated as an alcohol sensor at room-temperature operation with a fast recovery by UV irradiation. The TiO<inf>2</inf>/Pt/TiO<inf>2</inf> layers on SiO<inf>2</inf>/Si substrate were confirmed by Auger electron spectroscopy with the interdiffusion of each layer. The TiO<inf>2</inf>/Pt/TiO<inf>2</inf> layers on printed circuit board show the superior sensor response to alcohol in terms of the sensitivity and stability compared to the nonsandwich structure, that is, the only Pt layer or the TiO<inf>2</inf>/Pt structures. Moreover, the recovery time of the TiO<inf>2</inf>/Pt/TiO<inf>2</inf> was improved by UV irradiation-assisted recovery. The optimum TiO<inf>2</inf>/Pt/TiO<inf>2</inf> with thicknesses of the undermost TiO<inf>2</inf> layer, a Pt layer, and the topmost TiO<inf>2</inf> layer being 50 nm, 6 nm, and 5 nm, respectively, showed the highest response to ethanol down to 10 ppm. Additionally, TiO<inf>2</inf>/Pt/TiO<inf>2</inf> shows an excellent sensing stability and exhibits different sensing selectivity among ethanol, methanol, and 2-propanol. The sensing mechanism could be attributed to the change of Pt work function during vapor adsorption. The TiO<inf>2</inf> layer plays an important role in UV-assisted recovery by photocatalytic activity and the topmost TiO<inf>2</inf> acts as protective layer for Pt.