| Summary: | 碩士 === 國立臺灣海洋大學 === 機械與機電工程學系 === 95 === In this study the soft lithography technique is used to fabricate a fluorescence chip with three-dimensional hydrodynamic focusing structure. For 2D hydrodynamic focusing structure, sample flow is focused by two sides of sheath flow. However, particles are randomly distributed in the vertical direction, causing the strength of fluorescence signals wide dispersed. On the contrary, for 3D hydrodynamic focusing structure, the sample flow can be completely focused at the center of the channel by surrounding sheath flow. By controlling the rate of sheath flow and sample flow, sample flow can form a small and stable cylindrical flow that would allow fluorescent particles to be excited uniformly by laser.
We also derive formulae for diameters of focused sample flow according to the theory of laminar flow. Experimental data confirms the derived formula with correction of hydraulic diameter. Experimental results of fluorescence detection show that the coefficients of variation for 3D focusing is much lower than those of 2D focusing. As a consequence, the 3D focusing chip provides advantages of stable sample flow and highly uniform detection signals.
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