Microfluidics and Nanofluidics

, Volume 3, Issue 1, pp 19–25

Control of serial microfluidic droplet size gradient by step-wise ramping of flow rates

Research Paper

DOI: 10.1007/s10404-006-0093-8

Cite this article as:
Collins, J. & Lee, A.P. Microfluid Nanofluid (2007) 3: 19. doi:10.1007/s10404-006-0093-8


This paper describes a method to control and detect droplet size gradient by step-wise flow rate ramping of water-in-oil droplets in a microfluidic device. The droplets are generated in a cross channel device with two oil inlets and a water inlet. The droplet images are captured and analyzed in a time sequence in order to quantify the droplet generation frequency. It is demonstrated that by controlling the ramping of the oil flow rates it is possible to manipulate the ramping of droplet sizes. Increasing or decreasing of droplet sizes is achieved for a step-wise triangular ramping profile of the oil flow rate. The dynamic behavior of droplets due to the step-wise flow pulses is investigated. Uniform linear size ramping of water-in-oil droplets from 73 to 83 μm in diameter is generated with an oil flow ramping range from 1 to 11 μL/min in a minimum of five steps while water flow rate is held constant at 2 μL/min.


Microfluidic droplets Droplet sensing High speed imaging Droplet generation frequency Microdroplet array 

Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  1. 1.Department of Biomedical EngineeringUniversity of CaliforniaIrvineUSA
  2. 2.Department of Mechanical and Aerospace EngineeringUniversity of CaliforniaIrvineUSA

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