Microfluidics and Nanofluidics

, Volume 18, Issue 5–6, pp 1247–1254

In situ seriate droplet coalescence under an optical force

  • Jin Ho Jung
  • Kyung Heon Lee
  • Ghulam Destgeer
  • Kang Soo Lee
  • Hyunjun Cho
  • Byung Hang Ha
  • Hyung Jin Sung
Research Paper

Abstract

We demonstrated the induced coalescence of droplets under a highly accurate optical force control. Optical scattering and gradient forces were used to push and trap the droplets prior to coalescence within a microfluidic channel. The behavior of the droplets under the influence of an optical force was predicted using an analytical model that agreed well with the experimental data. The optical gradient force accelerated and decelerated the droplet within the laser beam region, and the drag force acting on the droplet was thoroughly characterized. A description of the optical trap was presented in terms of the momentum transfer from the photons to the droplet, effectively restricting droplet motion inside the microfluidic channel prior to coalescence. A phase diagram was plotted to distinguish between the three regimes of droplet coalescence, including the absence of coalescence, coalescence, and multiple coalescence events. The phase diagram permitted the laser power input and the net flow rate in the microfluidic channel to be estimated. This technique was applied to the synthesis of biodegradable gel microparticles.

Keywords

Droplet coalescence Optical force Two-phase flow Biodegradable gel Droplet trapping 

Supplementary material

Supplementary material 1 (AVI 5178 kb)

10404_2014_1522_MOESM2_ESM.doc (56 kb)
Supplementary material 2 (DOC 56 kb)

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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Jin Ho Jung
    • 1
  • Kyung Heon Lee
    • 1
  • Ghulam Destgeer
    • 1
  • Kang Soo Lee
    • 1
  • Hyunjun Cho
    • 1
  • Byung Hang Ha
    • 1
  • Hyung Jin Sung
    • 1
  1. 1.KAISTDaejeonRepublic of Korea

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