Microfluidics and Nanofluidics

, Volume 16, Issue 4, pp 635–644 | Cite as

Optical separation of droplets on a microfluidic platform

  • Jin Ho Jung
  • Kyung Heon Lee
  • Kang Soo Lee
  • Byung Hang Ha
  • Yong Suk Oh
  • Hyung Jin SungEmail author
Research Paper


This paper describes the optical separation of microdroplets according to their refractive indices. The behavior of the droplets was characterized in terms of the optical force and the hydrodynamic effects present upon illumination of the droplets in a direction normal to the flow direction in a rectangular microfluidic channel. The optical forces acting on the droplets and the resultant droplet trajectories were analyzed and compared with the numerically predicted values. The relationship between the drag force and optical force was examined to understand the system performance properties in the context of screening applications involving the removal of unwanted droplets. Two species of droplets were compared for their photophoretic displacements by varying the illumination intensity. Because the optical forces exerted on the droplets were functions of the refractive indices and sizes of the droplets, a variety of chemical species could be separated simultaneously.


Optical force Droplet Two-phase flow Droplet migration Passive separation Optofluidics 



This work was supported by the Creative Research Initiatives program (No. 2013-003364) of the National Research Foundation of Korea (MSIP).

Supplementary material

Supplementary material 1 (MPG 798 kb)

Supplementary material 2 (MPG 1794 kb)

Supplementary material 3 (MPG 3454 kb)


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Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Jin Ho Jung
    • 1
  • Kyung Heon Lee
    • 1
  • Kang Soo Lee
    • 1
  • Byung Hang Ha
    • 1
  • Yong Suk Oh
    • 1
  • Hyung Jin Sung
    • 1
    Email author
  1. 1.Department of Mechanical EngineeringKAISTDaejeonKorea

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