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Subject: search.filters.subject.Optical detection system

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    Item type:Publication,
    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.