We report the droplet generation behavior of a microfluidic droplet generator with a controllable deformable membrane wall using experiments and analytical model. The confinement at the droplet generation junction is controlled by using external pressure, which acts on the membrane, to generate droplets smaller than junction size (with other parameters fixed) and stable and monodispersed droplets even at higher capillary numbers. A non-dimensional parameter, i.e., controlling parameter Kp, is used to represent the membrane deformation characteristics due to the external pressure. We investigate the effect of the controlled membrane deformation (in terms of Kp), viscosity ratio λ and flow rate ratio r on the droplet size and mobility. A correlation is developed to predict droplet size in the controllable deformable microchannel in terms of the controlling parameter Kp, viscosity ratio λ and flow rate ratio r. Due to the deflection of the membrane wall, we demonstrate that the transition from the stable dripping regime to the unstable jetting regime is delayed to a higher capillary number Ca (as compared to rigid droplet generators), thus pushing the high throughput limit. The droplet generator also enables generation of droplets of sizes smaller than the junction size by adjusting the controlling parameter.
Droplet Size Capillary Number Viscosity Ratio Droplet Generator Flow Rate Ratio
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This work was supported by the Indian Institute of Technology Madras via Project No. ERP1314018RESFASHS. The authors also acknowledge the CNNP, IIT Madras for supporting the photolithography work.
Garstecki P, Fuerstman MJ, Stone HA, Whitesides GM (2006) Formation of droplets and bubbles in a microfluidic T-junction-scaling and mechanism of break-up. Lab Chip 6:437–446. doi:10.1039/b510841aCrossRefGoogle Scholar
Gupta A, Kumar R (2010) Flow regime transition at high capillary numbers in a microfluidic T-junction: viscosity contrast and geometry effect. Phys Fluids 22:122001. doi:10.1063/1.3523483CrossRefGoogle Scholar
Kemna EWM, Schoeman RM, Wolbers F (2012) High-yield cell ordering and deterministic cell-in-droplet encapsulation using Dean flow in a curved microchannel. Lab Chip 12:2881–2887. doi:10.1039/c2lc00013jCrossRefGoogle Scholar
Kohler JM, Henkel T (2005) Chip devices for miniaturized biotechnology. Appl Microbiol Biotechnol 69:113–125CrossRefGoogle Scholar
Lee C-H, Hsiung S-K, Lee G-B (2007) A tunable microflow focusing device utilizing controllable moving walls and its applications for formation of micro-droplets in liquids. J Micromech Microeng 17:1121–1129. doi:10.1088/0960-1317/17/6/004CrossRefGoogle Scholar
Lignel S, Drelich A, Sunagatullina D et al (2014) Differential scanning calorimetry analysis of W/O emulsions prepared by miniature scale magnetic agitation and microfluidics. Can J Chem Eng 92:337–343. doi:10.1002/cjce.21925CrossRefGoogle Scholar
Yoshida J, Ohmori K, Takeuchi H (2005) Treatment of ischemic limbs based on local recruitment of vascular endothelial growth factor-producing inflammatory cells with ultrasonic microbubble destruction. J Am Coll Cardiol 46:899–905CrossRefGoogle Scholar