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Droplet Formation at Microfluidic T-junctions



David A. LaVan, Xiang Xu


Analysis of droplet formation in microfluidic systems is important to understand the operation of these devices, and to permit optimal design and process control. Droplet formation in microfluidic T-junction devices was studied using experimental and numerical methods. The simulations agree well with experimental data from PDMS devices; they show that droplet pinch-off is controlled not by viscous stress, but rather caused by pressure buildup after channel blocking due to the second phase. The period of droplet formation is dependent on velocity of the flow, but not viscosity or interface tension of the fluids. Analysis using dimensionless period, which is equivalent to dimensionless droplet length, shows that dimensionless period is controlled primarily by water fraction but is also dependent on velocity following a power-law relationship. Higher values of capillary number tend to extend the distance for droplet pinch-off. Droplet length does depend on flow velocity at low velocities, but reaches a relatively constant length at higher flow velocities. The coefficient of variation of droplet volume/length increases with increasing capillary number.
Proceedings Title
Microelectromechanical SystemsýMaterials and Devices II
Conference Dates
November 30-December 4, 2008
Conference Location
Boston, MA
Conference Title
2008 Materials Research Society Fall Meeting


MEMS, microfluidic, finite element modeling, droplet, bioMEMS, two-phase flow


LaVan, D. and Xu, X. (2008), Droplet Formation at Microfluidic T-junctions, Microelectromechanical SystemsýMaterials and Devices II, Boston, MA, [online], (Accessed April 21, 2024)
Created December 31, 2008, Updated February 19, 2017