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Author: search.filters.author.Chodjarusawad, Thanawee

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    Selective formations of antimony-dopant for highly sensitive nitrogen dioxide responsive behavior of tin oxide-based chemiresistive sensor
    (2025-02-15)
    Rattanawarinchai, Prapakorn
    ;
    Khemasiri, Narathon
    ;
    Rahong, Sakon
    ;
    Rangkasikorn, Adirek
    ;
    Kayunkid, Navaphun
    Here, selective formation of antimony (Sb) dopant species responsible for highly sensitive gas sensors based on tin oxide (SnO<inf>2</inf>) film grown via pulsed laser deposition is presented. By elevating a forming energy through controlling substrate temperature, not only crystallinity of Sb-SnO<inf>2</inf> (ATO) is notably enhanced but the Sb<sup>5 +</sup> also predominantly replace at Sn<sup>4+</sup> site rather than Sb<sup>3+</sup> counterpart. Such Sb-species selection plays a crucial role on the density of oxygen vacancy and free electron enabling to rationally design conductive behaviour of ATO film from insulative to degenerated semiconductor. As a practical example, detection of nitrogen dioxide (NO<inf>2</inf>) gas is selected as an application model. We found a narrow window for high NO<inf>2</inf> sensing performance of ATO film which strongly corresponds with the amount of carrier density. At certain window, ATO film exhibits high NO<inf>2</inf> response of 24.65 (10 ppm) and low limit of detection of 0.5 ppm, which is 5-fold higher and 10-fold lower than that of undoped-SnO<inf>2</inf>, respectively. Our finding demonstrates a facile approach to design over the chemical state, defect, and conductivity of the active sensing layer, allowing us to achieve an excellent sensing performance of functional materials conjugated to a nano-electronic platform.
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    Relationship between overall difference decision and electronic tongue: Discrimination of civet coffee
    (2016-07-01)
    Lopetcharat, Kannapon
    ;
    Kulapichitr, Fareeya
    ;
    Suppavorasatit, Inthawoot
    ;
    Chodjarusawad, Thanawee
    ;
    Phatthara-Aneksin, Anat
    This paper demonstrates a new approach to relate electronic tongue (E-tongue) to human perception for fine quality of beverage. Six civet, one weasel and one non-civet coffees were chosen as the testing platform. The sensory test based on the overall difference method by pair comparison followed by sureness-rating tasks was divided into three experiments. In each, 12-14 consumers were asked to express differences in six pairs of hot brew coffee samples on a four-point scale. The results were analyzed by the Multi-Dimensional Scaling (MDS) analysis. An in-house electronic tongue based on cyclic voltammetry and the Principal Component Analysis (PCA) was applied to measure the coffee samples, alongside the panel test. The relationship between PCA and MDS solutions was obtained by Generalized Procrustes Analysis (GPA), which reveals a strong correlation between E-tongue and human perception. Both were able to identify differences between all coffee samples from different sources.
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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.