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Author: search.filters.author.Kittidachachan, Pattareeya

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    Photon frequency management materials for efficient solar energy collection
    (2015-01-01)
    Danos, Lefteris
    ;
    Meyer, Thomas J.J.
    ;
    Kittidachachan, Pattareeya
    ;
    Fang, Liping
    ;
    Parel, Thomas S.
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    Improved light harvesting in N719 sensitized nanocrystalline Tio2 solar cells with coumarin 6 dye
    (2014-01-01)
    Kittidachachan, Pattareeya
    ;
    Soonpanich, Wichayapom
    ;
    Damrongsak, Badin
    Dye-sensitized solar cells (DSSCs) are a promising alternative to conventional semiconductor solar cells due to their ease of fabrication and low manufacturing cost. Ru-based dyes, particularly N719, are the typical dye for DSSC applications. However, N719-based DSSCs have weak absorbance at a wavelength around 440 nm. In this work, we aimed to improve light absorption of the N719-based DSSCs by adding a luminescent dye, Coumarin 6(C6), into an electrolyte. C6 dye were chosen as it has an absoption and luminescence spectrum complementary to that of N719. The absorption and luminescence spectra of the C6 solution with different dye concentrations, ranging from 1-25 uM, were investigated in order to find the optimum concentration that is suitbale for the DSSC applications. Moreover, N719 based DSSCs with and without C6 added were fabricated and experimental compared. The measurement results show that the N719-based DSSC with C6 dye has the improvement in both short circuit current and device efficiency.
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    Prototype microfluidic system for fluorescence-based chemical sensing
    (2014-01-01)
    Kittidachachan, Pattareeya
    ;
    Rujihan, Suparat
    ;
    Damrongsak, Badin
    A prototype microfluidic system for fluorescence detection is presented in this paper. The system consists of an excitation light source, a polymer-based microfluidic channel and an optical detector. Experiments are conducted to demonstrate use of the developed system for fluorescence detection in chemical applications. Three fluorescent dyes - Rhodamine 6G, Coumarin 153 and DCM - with different concentrations ranging from 100 nM to 5 mM are used as the analyte in the experiments. Relationship between the photo-response of the microfluidic system and concentration of fluorescent dyes is investigated. The results are compared to that obtained from a bulk system where the analyte under test is dispensed into a standard-size cuvette. In the bulk system, we found a decrease in the fluorescence signal when dye concentration is higher than 10-5 M for Rhodamine 6G and 10-4 M for Coumarin 153 and DCM. This is probably due to the re-absorption and self-quenching phenomena, which result in low quantum yield of fluorescent dyes at high concentration. However, this problem is not found in microfluidic systems with a low detection volume. In addition, the relationship between the photo-response of the system corresponding to different dye concentrations was modeled based on Beer Lambert's law. The measured results agreed will with the theoretical model.
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    Poly(dimethylsiloxane) microlens array integrated with microfluidic channel for fluorescence spectroscopy detection
    (2013-09-18)
    Rujihan, Suparat
    ;
    Damrongsak, Badin
    ;
    Kittidachachan, Pattareeya
    Fluorescence spectroscopy detection has been commonly used in chemical and biochemical applications as it provides a good reliability and high sensitivity. Commercially available fluorescence spectroscopy system is typically bulky and expensive, hence making it inconvenience for on-site measurement which requires portable systems. However, the drawback of small devices is that it has a low detection volume, resulting in low fluorescence signal. In this paper, we report a microfluidic channel implemented with a microlens array for enhancing the performance of fluorescence spectroscopy detection. The microlens array was used to focus an excitation light onto the microchannel, thus expecting the increase in fluorescence detection signal. Both microchannels and microlens arrays were individually fabricated from poly-dimethylsiloxane (PDMS) using low-cost printed-circuit-board master molds. The fabrication and characterization of PDMS-based microlens arrays are discussed. In short, the microlens in plano-convex shape was designed with diameters of 700, 800 and 900 microns. The fabricated microlens arrays were characterized for radius of curvatures, SAGs and focal lengths. The plano-convex microlens array was then integrated into a microfluidic system in order to investigate the overall performance of fluorescence spectroscopy detection. Experiments were conducted with two fluorescence dyes, i.e. Rhodamine 6G and Coumarin 153. The preliminary results revealed that the PDMS microlens array implemented on the designed system shows potential for improving excitation and emission light intensity and, as a consequence, signal to background ratio of the fluorescence spectroscopy detection. © 2013 SPIE.