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    Metal Oxide Nanostructures Enhanced Microfluidic Platform for Efficient and Sensitive Immunofluorescence Detection of Dengue Virus
    (2023-11-01)
    Pormrungruang, Pareesa
    ;
    Phanthanawiboon, Supranee
    ;
    Jessadaluk, Sukittaya
    ;
    Larpthavee, Preeda
    ;
    Thaosing, Jiraphon
    Rapid and sensitive detection of Dengue virus remains a critical challenge in global public health. This study presents the development and evaluation of a Zinc Oxide nanorod (ZnO NR)-surface-integrated microfluidic platform for the early detection of Dengue virus. Utilizing a seed-assisted hydrothermal synthesis method, high-purity ZnO NRs were synthesized, characterized by their hexagonal wurtzite structure and a high surface-to-volume ratio, offering abundant binding sites for bioconjugation. Further, a comparative analysis demonstrated that the ZnO NR substrate outperformed traditional bare glass substrates in functionalization efficiency with 4G2 monoclonal antibody (mAb). Subsequent optimization of the functionalization process identified 4% (3-Glycidyloxypropyl)trimethoxysilane (GPTMS) as the most effective surface modifier. The integration of this substrate within a herringbone-structured microfluidic platform resulted in a robust device for immunofluorescence detection of DENV-3. The limit of detection (LOD) for DENV-3 was observed to be as low as 3.1 × 10<sup>−4</sup> ng/mL, highlighting the remarkable sensitivity of the ZnO NR-integrated microfluidic device. This study emphasizes the potential of ZnO NRs and the developed microfluidic platform for the early detection of DENV-3, with possible expansion to other biological targets, hence paving the way for enhanced public health responses and improved disease management strategies.
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    Heavy metal detection by electrochemical electronic tongue with poly(thiophene)-metal oxide nanoparticle composite electrodes
    (2011-12-01)
    Saeteaw, Kanjana
    ;
    Tumcharern, Gamolwan
    ;
    Piyakulawat, Phimwipha
    ;
    Asawapirom, Udom
    ;
    Porntheeraphat, Supanit
    Rapid monitoring methods of heavy metals in water are in great demand for industrial environmental managements. This work aims to develop a heavy metal sensing device based on an electrochemical electronic tongue using a hybrid composite of metal oxide nanoparticles and conductive polymer as the working electrodes. The electrodes were prepared by drop-casting colloidal mixtures of Regioregular poly(3-hexylthiophene) (P3HT) and metal oxide nanoparticles (ZnO or TiO <inf>2</inf>) in chloroform onto a fluorine-doped tin oxide (FTO) glass. Optical microscopy measurements reveal some microstructural organization of the metal oxide-P3HT composite films on the electrodes, in comparison to a smooth P3HT film. Cyclic voltammetry (CV) measurements using bare FTO, P3HT, P3HT/ZnO and P3HT/TiO <inf>2</inf> electrodes were performed on aqueous solutions of various metal acetates at the concentration of 0.01M. The Principal Component Analysis (PCA) was applied to the CV results to obtain the classification of the data from the various metal salt solutions. The PCA score plot exhibits a clear separation of the data groups of different heavy metals, with the highest distinction between zinc and lead. The PCA loading plot confirms that the different electrochemical nature of the various electrodes is responsible for such distinctive classification. Further work is to examine the capability of the electrochemical electronic tongues for semi-quantitative analyses of the metal salt concentration. © 2011 IEEE.
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    Effect of annealing temperature on TiO2 structured films by the glancing angle deposition with incline spinning substrate on rotating holder method
    (2011-10-13)
    Mekla, Vatcharinkorn
    ;
    Pukird, Supakorn
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    Porntheerapat, Supanit
    ;
    This work reports the effects of annealing on the TiO<inf>2</inf> thin films prepared by the GLAD technique with incline spinning substrate on rotating holder (ISSRH) by using the electron beam evaporation. The prepared films were heated at 500 C , 600 C and 700 C for 2 hr in air. The microstructure of films was studied by UV- visible photometer, X-ray diffraction, XRD and field emission scanning electron microscope, FE-SEM. The results showed the sample films exhibited continuity distribution of the crystalline. The XRD peaks of anatase phase were increased slightly vary with annealing temperature. The porosity of films has been changed with increasing temperature. The film with annealing at 500 C showed the percentage of transferring range of 442-800 nm wavelengths and the maximum absorption of light at 418 nm wavelengths. The calculation evidenced the energy band gap of TiO<inf>2</inf> nanostructures was around 3.41 eV. © 2011 IEEE.
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    Cell phone-based two-dimensional spectral analysis for banana ripeness estimation
    (2012-06-20)
    Intaravanne, Yuttana
    ;
    Sumriddetchkajorn, Sarun
    ;
    It is known that when green fruits such as bananas and mangoes grow from the immature to the ripe stages, their color changes from green to yellow. However, once the green fruits are yellow, it is difficult to classify them into the ripe and the overripe stages. Here, we propose and experimentally demonstrate for the first time a two-dimensional banana ripeness level sensor by using a cell phone. Our key approach relies on simultaneous analysis of two broad-spectral images of the banana under white light and ultraviolet illuminations. Particularly, our selected color ratios from these two broad-spectral images are used for spatially and specifically classifying the whole banana into immature, ripe, and overripe zones. Experimental proof of concept using a smart mobile phone is highlighted, featuring fast response, portability, and ease of implementation. © 2012 Elsevier B.V.
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    Silicon nitride thin films deposited by reactive gas-timing magnetron sputtering for protective coating applications
    (2015-01-01) ;
    Paleeya, N.
    ;
    Sae-tang Phromyothin, D.
    ;
    Horprathum, M.
    ;
    Porntheeraphat, S.
    Silicon nitride is a promising alternative to carbon based materials for protective coatings, owing to its compatibility with existing silicon-based microfabrication. The complexity of the fabrication processes and contaminations hamper fine-tuning to obtain desirable coating properties. We have explored the reactive gas-timing rf plasma sputtering technique for silicon nitride thin film deposition as an alternative method to fine-tune the film properties. The gas-timing technique controls the on-off sequence of the sputtering gas (Ar) and the reactive gas (N<inf>2</inf>) during deposition. We focus this investigation to the effect of the Ar:N<inf>2</inf> gas timing ratio (10:0, 10:1, 10:3, 10:5, 10:7 and 10:10) on the composition, the morphology, the corrosion resistance, and the hardness properties of the films, in comparison to the films deposited by conventional reactive sputtering with Ar-N<inf>2</inf> gas mixture. These deposited silicon nitride films were characterized by Auger electron spectroscopy, Raman spectroscopy, and atomic force microscopy. The chemical resistance was measured by the electrochemical corrosion test in sulfuric acid, while the hardness properties were obtained by nanoindentation. The results reveal that although the nitrogen content in the films increases only slightly when the N<inf>2</inf> timing is prolonged, the corrosive current of the films decreases abruptly. A thin passivating oxidized layer is found to play a major role in the corrosion resistance. In contrast, the hardness properties exhibit a uniform variation with the N<inf>2</inf> timing. The gas-timing sequence may induce morphological changes the underlying silicon nitride films. The highest hardness obtained by the gas-timing technique almost doubles that produced by the conventional mixed gas sputtering. Thus the reactive gas-timing technique suggests a new route to selectively control the properties of silicon nitride films with minor modification to existing microfabrication processes.
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    Modulation spectroscopy study of inorganic-organic hybrid quantum well-like nanostructures
    (2007-08-28) ;
    The optical transition energy in zinc selenide (ZnSe)/tris(8- hydroxyquinoline) aluminum (Alq3) /N,N'-Bis(3-methyphenyl)-N,N -diphenylbenzidine inorganic-organic hybrid quantum well-like nanostructures (hybrid QW-like nanostructure) with well thickness of Aq3 from 10 to 50 nm were investigated by modulation spectroscopy as electroreflectance (ER) measurements. ER features due to optical transition energy were observed in the hybrid QW of well thickness. The transition energies were determined by fitting the ER spectra to the theoretical line-shape expression. The subband transition energy decreased with increasing well thickness might be due to the increase of well results in the reduction of quantum confinement energy. © 2007 IEEE.
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    Application of double gate ion sensitive field effect transistor for detection of fluid flow rate in micro-channel
    (2010-02-05)
    Jiemsakul, T.
    ;
    Trithaveesak, O.
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    Bunjongpru, W.
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    Hruanun, C.
    ;
    Poyai, A.
    In this work a micro flow sensor, using a double gate Ion Sensitive Field Effect Transistor (ISFET) and two metal electrodes, for fluid flow rate measurement in micro-channels were fabricated and demonstrated. By the channel fabrication the molds were patterned reversely on a silicon wafer using Deep Reactive Ion Etcher (DRIE). The double gate ISFET and two metal electrodes were placed on the mold in the distance 15 millimeters. The channels were formed using polydimethylsiloxane (PDMS) from the mold with the width 1000 and 2000 micrometer and the depth of 250 micrometer. After removing PDMS from the mold the channel was bonded with glass substrate by RF plasma technique. By the verification of flow sensors working range water and one mole of sodium nitrate solution were alternated in flow channel. The fluid flow rate were compared with the flow rate from weighing. It found from the comparison that the high deviation was found at low flow rate. Furthermore, the deviation depends also on the dimension of the flow channel. © (2010) Trans Tech Publications.
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    The effect of substrates temperature on pentacene thin films prepared by organic thermal evaporator
    (2007-12-01)
    Chanhom, Annop
    ;
    The influence of substrate temperature on the physical and optical characteristics of pentacene thin films have been investigated by the experiment and using atomic force microscopy and UV- Visible spectrophotometer. The pentacene thin films were prepared on glass substrates by organic source evaporating system and the substrate temperature was varied between room temperature and 120 °C. The results of AFM images and light absorbance indicate that the variation of substrate temperature has a distinguishable impact on both physical and optical properties of pentacene thin films. The AFM images show the increasing morphological grain size when the substrate temperature is risen. In addition, the thin films absorbance graph shown the dominant peaks at 1.82 eV, 1.97 eV, 2.14 eV 2.30 and 2.50 eV are all clearly diminished with increasing substrate temperature. The effect of substrate temperature on pentacene thin film properties are described in detail. © 2007 IEEE.
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    Tantalum oxide bio-photonics thin film grown by gas-timing innovation technique
    (2013-09-18) ;
    Porntheeraphat, S.
    ;
    Horprathum, M.
    ;
    Chananonnawathorn, C.
    ;
    Bunjongpru, W.
    Tantalum oxide (TaxOy) as high refractive index material has been grown on p-type silicon and quartz substrates by R.F. magnetron sputtering with our innovative technique called "reactive-gas timing". The reactive gas timing technique is an on-off time period sequence between argon (Ar) and oxygen (O2) plasma during sputtering process. The technique of gas-timing plays the effect on the properties of TaxOy thin film. The bombarded Ar-plasma was varied at 2, 5 and 8 sec, while the period of reactive O2-plasma was kept at 5 sec in this experiment. The physical and optical properties were investigated by using X-ray diffraction (XRD), Atomic Force Microscope (AMF), UV-Visible spectrometer and Spectroscopic Ellipsometer, respectively. The XRD spectra and AFM photographs show all films are amorphous phase with smooth feature. Meanwhile the transmittance of sputtered thin film decreases with 10% and the absorption edge shifts to lower energy with the increasing of the argon period from 2 sec to 8 sec. The refractive index as showed by ellipsometry slightly increases from 2.08 to 2.17 at wavelength 550 nm with the increasing of argon period from 2 sec to 8 sec. The increasing of the refractive index might dues to tantalum (Ta) rich which consists in thin films. The Ar-plasma period in the deposited film plays an important role on the properties of the TaxOy thin films especially as optical refractive index material. © 2013 SPIE.
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    Characterization of ITO thin films on PET substrates prepared by gas-timing RF magnetron sputtering
    (2005-11-09)
    Klamchuen, Annop
    ;
    Pornteeraphat, Nisaporn
    ;
    Indium tin oxide (ITO) thin films were deposited on polyethylene terephthalate (PET) substrates at room temperature by RF magnetron sputtering with a new technique, called gas-timing. The influence of RF power on properties of ITO thin films was investigated. From the x-ray diffraction measurement of the ITO thin films grown by this technique, cubic, nano-crystalline structure with predominant (222) and (400) orientation was observed. It was found that the increasing of RF power yielded to decrease in the sheet resistance of ITO thin films. The sheet resistance of ITO thin films deposited by RF power of 40 watts had the lowest value of 8 Ω/□. By the gas-timing technique, the ITO thin films on PET substrates were achieved with high transmittance in visible region of 90%. Therefore, the gas-timing RF magnetron sputtering is a promising technique to achieve the ITO thin film on PET substrate with low resistivity and high transmittance in visible region without substrate heating and post-deposition annealing. © 2005 The Surface Science Society of Japan.