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Global network design for robust operation of microfluidic droplet generators with pressure-driven flow

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Abstract

This study investigates the influence of both local generator design and global network architecture in improving the stability and operational performance of microfluidic droplet generators. We identify naturally occurring short-term and long-term oscillations that are related to changes in the flow of the two phases. Short-term oscillations are related to the creation of each droplet and are quantified by tracking droplet speed in the network. Long-term oscillations are caused by dynamic feedback associated with the periodic change in the hydrodynamic resistance of the network as droplets enter and exit the system. Our analysis identifies that these long-term oscillations are best quantified by measuring changes in droplet spacing rather than the conventional method of using droplet size. Furthermore, we find that these long-term oscillations have a periodicity that matches the residence time of droplets within the network. In combination with experiments, a simple compact model is developed to study these oscillations and guide the network design of droplet generators. As part of this analysis a set of design rules is developed to help improve overall generator performance using pressure-driven flow.

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Acknowledgments

The authors gratefully acknowledge the support from the Natural Sciences and Engineering Research Council of Canada, Canada Foundation for Innovation of Canada, International Science and Technology Program of Canada and Ontario Centers of Excellence to Dr. Carolyn Ren through her grants, and the Canada Graduate Scholarship to Tomasz Glawdel.

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Authors and Affiliations

  1. Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Ave W., Waterloo, Canada

    Tomasz Glawdel & Carolyn L. Ren

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  1. Tomasz Glawdel
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  2. Carolyn L. Ren
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Correspondence to Carolyn L. Ren.

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Glawdel, T., Ren, C.L. Global network design for robust operation of microfluidic droplet generators with pressure-driven flow. Microfluid Nanofluid 13, 469–480 (2012). https://doi.org/10.1007/s10404-012-0982-y

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  • DOI: https://doi.org/10.1007/s10404-012-0982-y

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