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A PDMS-Based Cylindrical Hybrid Lens for Enhanced Fluorescence Detection in Microfluidic Systems
Institute of Imaging and Biomedical Photonics, National Chiao Tung University, Tainan 71150, Taiwan
Department of Medical Research, Chi-Mei Medical Center, Tainan 71004, Taiwan
Department of Chemical Engineering, National Cheng Kung University, Tainan 70101, Taiwan
* Author to whom correspondence should be addressed.
Received: 2 December 2013; in revised form: 4 January 2014 / Accepted: 27 January 2014 / Published: 13 February 2014
Abstract: Microfluidic systems based on fluorescence detection have been developed and applied for many biological and chemical applications. Because of the tiny amount of sample in the system; the induced fluorescence can be weak. Therefore, most microfluidic systems deploy multiple optical components or sophisticated equipment to enhance the efficiency of fluorescence detection. However, these strategies encounter common issues of complex manufacturing processes and high costs. In this study; a miniature, cylindrical and hybrid lens made of polydimethylsiloxane (PDMS) to improve the fluorescence detection in microfluidic systems is proposed. The hybrid lens integrates a laser focusing lens and a fluorescence collecting lens to achieve dual functions and simplify optical setup. Moreover, PDMS has advantages of low-cost and straightforward fabrication compared with conventional optical components. The performance of the proposed lens is first examined with two fluorescent dyes and the results show that the lens provides satisfactory enhancement for fluorescence detection of Rhodamine 6G and Nile Red. The overall increments in collected fluorescence signal and detection sensitivity are more than 220% of those without lens, and the detection limits of Rhodamine 6G and Nile red are lowered to 0.01 μg/mL and 0.05 μg/mL, respectively. The hybrid lens is further applied to the detection of Nile red-labeled Chlorella vulgaris cells and it increases both signal intensity and detection sensitivity by more than 520%. The proposed hybrid lens also dramatically reduces the variation in detected signal caused by the deviation in incident angle of excitation light.
Keywords: microfluidic systems; optical components; hybrid lens; fluorescence measurement; polydimethylsiloxane (PDMS)
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Lin, B.-S.; Yang, Y.-C.; Ho, C.-Y.; Yang, H.-Y.; Wang, H.-Y. A PDMS-Based Cylindrical Hybrid Lens for Enhanced Fluorescence Detection in Microfluidic Systems. Sensors 2014, 14, 2967-2980.
Lin B-S, Yang Y-C, Ho C-Y, Yang H-Y, Wang H-Y. A PDMS-Based Cylindrical Hybrid Lens for Enhanced Fluorescence Detection in Microfluidic Systems. Sensors. 2014; 14(2):2967-2980.
Lin, Bor-Shyh; Yang, Yu-Ching; Ho, Chong-Yi; Yang, Han-Yu; Wang, Hsiang-Yu. 2014. "A PDMS-Based Cylindrical Hybrid Lens for Enhanced Fluorescence Detection in Microfluidic Systems." Sensors 14, no. 2: 2967-2980.