微液滴系統(Digital microfluidics)因為具有快速分析、高產率、獨立環境控制等優點，在化學、生物等領域正快速發展中。由於微液滴的生成受到許多參數影響，例如流量、界面活性劑、流道形狀等，因此在本實驗中，首先利用微量幫浦(syringe pump)來控制通入T型微流道中大豆油與水的流量，產生高均勻性的微小液滴，並探討流量與界面活性劑對於微液滴生成及大小的影響。由實驗結果發現，當基材的平整度較高或是有添加界面活性劑時可以穩定液滴的生成；另外，在流量的影響上，改變大豆油與水的流量使Capillary number在2.47×10-3 與4.4×10-1之間時，可產生長度(橢圓形長軸)約在225 ~ 107 μm之間的微液滴，液滴與各參數間呈現L/W_c =1.258φ^0.159 Ca^(-0.081)*的無因次關係式。在相同的油及水流量下，加入界面活性劑會使液滴生成更穩定且產生更小顆的液滴。在應用上，通入被Nile red染色的藻類並觀察其被包覆在液滴中之情形；另外，也嘗試在彎曲流道中進行Nile red的即時混合與萃取之研究。本研究提供詳細資訊以利於建立可即時偵測藻油量的微流體平台。
*L：液滴長度；wc：液滴生成處的流道寬度；φ=Q_d/Q_c ，Qd：分散相流量，Qc：連續相流量；Ca= (μ_c v_c)/γ，γ：兩相間的界面張力、μc：連續相的黏度、vc：連續相的速度。

Digital microfluidics has been widely applied for biological and chemical research because of its abilities in rapid analysis, high throughput, and independent droplet manipulation. Many parameters affect the formation of droplets such as flow rates, surfactant concentrations, and geometries of microchannels. Manipulating and generating droplets with accuracy are important in obtaining meaningful results. In this study, soybean oil and water (with Tween 20 added in some sets of experiments) were used as continuous and disperse phases, respectively, to create highly monodispersed droplets in a T-junction microchannel. We found that droplets can be generated stably using smooth substrates or adding Tween 20. We have generated monodispersed droplets whose sizes were between 225 (μm) ~107 (μm) when the Capillary number was adjusted from 2.47×10-3 to 4.4×10-1. Adding surfactant decreased the length of droplets under the same flow rates. Furthermore, we obtained a simple relationship between the droplet lengths and the channel width, fluid viscosity and flow rates: L/W_c =1.258φ^0.159 Ca^(-0.081).*
Following this fundamental research, we used an aquareous solution containing microalgae (Chlorella vulgaris) that have been stained by Nile red as the disperse phase to generate microalgae-containing droplets. We successfully encapsulated various amounts of Nile red labeled microalgae in the droplets. Afterwards, we encapsulated Nile red into droplets to investigate the mixing and extraction of Nile red in a serpentine microchannel. Using this system, future integration of real-time labeling and detection for biological samples can be achieved.
*L: length of droplets; wc: width of channel where the droplet formed; Q= Q_d/Q_c ，Qd: flow rate of disperse phase, Qc: flow rate of continuous phase; Ca= (μ_c v_c)/γ, γ: interfacial tension between continuous and disperse phase, μc: viscosity of continuous phase, vc: velocity of continuous phase.

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