Design of a flow-controlled asymmetric droplet splitter using computational fluid dynamics
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In this work the design of a segmented flow microfluidic device is presented that allows droplet splitting ratios from 1:1 up to 20:1. This ratio can be dynamically changed on chip by altering an additional oil flow. The design was fabricated in PDMS chips using the standard SU-8 mold technique and does not require any valves, membranes, optics or electronics. To avoid a trial and error approach, fabricating and testing several designs, a computational fluid dynamics model was developed and validated for droplet formation and splitting. The model was used to choose between several variations of the splitting T-junction with the extra oil inlet, as well to predict the additional flow rate needed to split the droplets in various ratios. Experimental and simulated results were in line, suggesting the model’s suitability to optimize future designs and concepts. The resulting asymmetric droplet splitter design opens possibilities for controlled sampling and improved magnetic separation in bio-assay applications.
KeywordsAsymmetric splitting Droplets in micro-channels Segmented flow microfluidics Computational fluid dynamics
The authors thank the Flemish Institute for the Promotion of Innovation through Science and Development (IWT grant: 81166), the Flemish Fund for Scientific Research (FWO grant G0767.09 and Postdoctoral mandate Frederik Ceyssens), KU Leuven (OT project 08/023) and EU FP-7 Marie-Curie ITN-BioMax. Special thanks go to Mark Romanowski and Ralph Sperling from the Weitz lab of Harvard University who freely provided their custom perfluorinated surfactant as well as priceless advice.
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