Flow regime mapping of high inertial gas–liquid droplet microflows in flow-focusing geometries
- 754 Downloads
Confined gas–liquid droplet microflows present a lot of new perspectives for microfluidic systems that require the presence of a gaseous phase. In addition to the benefits associated with the discretization of reactive and sensing processes, the highly inertial droplets generated in these systems can enable fast efficient mixing by pair collisions as well as high system throughput due to the short convective timescales involved in the droplet transport. Presented herein is mapping of the geometry-specific droplet generation from a binary gas–liquid flow for different flow-focusing configurations. The dynamic interactions of inertia, shear stress, viscous and surface tension forces create three unique regimes in the gas–liquid flow rate space, providing adaptable flow configuration to specific applications. Analytical investigation and numerical analyses involving governing forces are also introduced to predict the effective droplet diameter versus gas flow rate. We found that the experimental results were well matched to the analytical predictions within 10 % of uncertainty.
KeywordsMicrofluidics Droplet generation High inertia Flow regime Flow-focusing geometry
This work was supported by DARPA 2008 Young Faculty Award (YFA) grant HR0011-08-1-0045 and is currently being supported by an NSF CAREER Award grant CBET-1151091. Authors thank Dr. Brian Carroll and David Choi for their helpful discussions for the experimental setup and Kevin Choi for his assistance in fabrication of microfluidic chips.
- Carroll B, Hidrovo CH (2012b) Experimental investigation of inertial mixing in colliding droplets. Heat Transf Eng 34:1–12Google Scholar
- Hindson BJ, Ness KD, Masquelier DA, Belgrader P, Heredia NJ, Makarewicz AJ, Bright IJ, Lucero MY, Hidessen AL, Legler TC, Kitano TK, Hodel MR, Petersen JF, Wyatt PW, Steenblock ER, Shah PH, Bousse KJ, Troup CB, Mellen JC, Wittmann DK, Erndt NG, Cauley TH, Koehler RT, So AP, Dube S, Rose KA, Montesclaros L, Wang S, Stumbo DP, Hodges SP, Romine S, Milanovich FP, White HE, Regan JF, Karlin-Neumann GA, Hindson CM, Saxonov S, Colston BW (2011) High-throughput droplet digital PCR system for absolute quantitation of DNA copy number. Anal Chem 83(22):8604–8610CrossRefGoogle Scholar
- Yasuda T, Imamura K, Hirase K (2009) Droplet transportation using EWOD-induced wettability gradient. In: Solid-state sensors, actuators and microsystems conference (Transducers), pp 413–416Google Scholar