Browsing by Author "Lin, Xin-Yu"

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Experimental Study on Microfluidic Mixing with Different Zigzag Angles
(2019-09-01)
Tsai, Chia-Hung Dylan
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Lin, Xin-Yu
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機械工程學系
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Department of Mechanical Engineering
This paper presents experimental investigations of passive mixing in a microfluidic channel with different zigzag angles. Zigzag channel is commonly used for microfluidic mixing because it does not need an additional control unit and can be easily implemented in a lab-on-a-chip system. In this work, microfluidic channels with six different zigzag angles, from theta = 0 degrees to theta = 75 degrees, are tested under ten different flow rates corresponding to Reynolds number from 0.309 to 309. Two colored liquids are mixed with the zigzag channels and mixing performance is evaluated based on the color of the pixels on the region of interest from captured images. According to the results, we found that the mixing performance is almost independent of the zigzag angle in the low-speed regime where its Reynolds number is less than 4. The mixing became very much depending on the zigzag angle in the high-speed regime where its Reynolds number is greater than 100. Microfluidic mixing is needed for Lab-on-a-chip applications in both low flow speed, such as medium perfusion for cell culture, and high flow speed, such as high-speed sensing on a point-of-care device. This work is aimed to provide practical information on zigzag mixing for chip design and applications.
Experimental Study on Microfluidic Mixing with Trapezoidal Obstacles in a 1000-Fold Span of Reynolds Number
(2019-01-01)
Lin, Xin-Yu
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Ito, Hiroaki
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Kaneko, Makoto
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Tsai, Chia-Hung Dylan
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機械工程學系
Mixing is important for microfluidic systems and placing obstacles in a flow path for generating advection, or splitting/recombination flows, is a very popular method for enhancing the mixing. In this paper, we present experimental investigations on such microfluidic mixing with four different shapes of trapezoidal obstacles and tested them in a 1000-fold span of Reynolds number (Re). The obstacles have four different base ratios 1, 3, 6 and 9, which indicate the ratios between the upper and lower bases of a trapezoid. Two different dyes, yellow and blue, were used for visualizing and evaluating the performance of mixing. The results show that, when the base ratio is 1, the mixing surprisingly becomes worse with the increase of the flowrate. When the ratio is 3 or 6, the mixing performance is first reduced with the increase of Re and then went through a transition around Re of 10 before it rapidly increases. When the ratio is 9, two transition points were found around Re of 10 and 100, respectively. The work provides useful information for realizing shape-dependent mixing performance, as well as for developing an intelligent lab-on-a-chip system.