Microfluidics and Nanofluidics

, Volume 10, Issue 5, pp 1033–1043 | Cite as

A tunable optofluidic lens based on combined effect of hydrodynamics and electroosmosis

  • Haiwang Li
  • Teck Neng WongEmail author
  • Nam-Trung Nguyen
Original Paper


This paper presents the modeling and experimental results of a liquid-core liquid-cladding optofluidic lens under the combined effect of hydrodynamics and electroosmosis. To allow the lens to be tuned by a voltage, the cladding fluids are electrically conducting, while the core fluid is non-conducting. Under constant flow rates, mathematical models of two-dimensional dipole flow in a circularly bounded domain and electric field outside the parallel-plate capacitor were used to predict the curvature of the interface. A test device with a circular lens chamber with 2 mm diameter and 250 μm height was fabricated in polymethylmethacrylate (PMMA) using thermal bounding method. Two cladding fluids (aqueous NaCl) and the core fluid (silicone oil) are introduced into the circular domain by syringe pumps. External electric fields are applied on the two cladding fluids. Under the same inlet volumetric flow rates, the applied voltages are varied to tune the curvature of the interfaces between the cladding fluids and the core fluid. The interface shape is measured using fluorescence imaging technique. The results show that the interfaces between the cladding fluids and the core fluid have optically smooth arc shape. Under fixed cladding flow rates, the same voltage forms symmetric biconvex lens only. Different voltages can form biconvex lens, plano-convex lens, and meniscus lens. The experimental results agree well with the presented analytical model.


Optofluidics Interface Microlens Hydrodynamic Electroosmosis 


  1. Camou S, Fujita H, Fujii T (2003) PDMS 2D optical lens integrated with microfluidic channels: principle and characterization. Lab Chip 3(1):40–45CrossRefGoogle Scholar
  2. Dino DC (2009) Inertial microfluidics. Lab Chip 9(21):3038–3046CrossRefGoogle Scholar
  3. Dong L, Jiang H (2008) Selective formation and removal of liquid microlenses at predetermined locations within microfluidics through pneumatic control. J Microelectromech Syst 17(2):381–392CrossRefGoogle Scholar
  4. Gao Y, Wang C, Wong TN, Yang C, Nguyen NT, Ooi KT (2007) Electro-osmotic control of the interface position of two-liquid flow through a microchannel. J Micromech Microeng 17(2):358–366CrossRefGoogle Scholar
  5. Gu Y, Li D (1998) The ζ-potential of silicone oil droplets dispersed in aqueous solutions. J Colloid Interface Sci 206(1):346–349CrossRefGoogle Scholar
  6. Kohlheyer D, Besselink GAJ, Lammertink RGH, Schlautmann S, Unnikrishnan S, Schasfoort RBM (2005) Electro-osmotically controllable multi-flow microreactor. Microfluid Nanofluid 1(3):242–248CrossRefGoogle Scholar
  7. Koplik J, Redner S, Hinch EJ (1994) Tracer dispersion in planar multipole flows. Phys Rev E 50(6):4650–4671CrossRefGoogle Scholar
  8. Li H, Wong TN, Nguyen NT (2009) Electroosmotic control of width and position of liquid streams in hydrodynamic focusing. Microfluid Nanofluid 7:489–497CrossRefGoogle Scholar
  9. Liu Y, Zeng X, Dong L, Jiang H (2009) Enhancing lab-on-a-chip performance via tunable parallel liquid mircolens arrays. Proceedings of SPIE - The International Society for Optical EngineeringGoogle Scholar
  10. Manz A, Effenhauser CS, Burggraf N, Harrison DJ, Seiler K, Fluri K (1994) Electroosmotic pumping and electrophoretic separations for miniaturized chemical analysis systems. J Micromech Microeng 4(4):257–265CrossRefGoogle Scholar
  11. Mao X, Waldeisen JR, Juluri BK, Huang TJ (2007) Hydrodynamically tunable optofluidic cylindrical microlens. Lab Chip 7(10):1303–1308CrossRefGoogle Scholar
  12. Mao X, Juluri BK, Lin SC, Shi J, Lapsley MI, Huang TJ (2008) In-plane tunable optofluidic microlenses. LEOS Summer Topical MeetingGoogle Scholar
  13. Mao X, Lin SCS, Lapsley MI, Shi J, Juluri BK, Huang TJ (2009) Tunable Liquid Gradient Refractive Index (L-GRIN) lens with two degrees of freedom. Lab Chip 9(14):2050–2058CrossRefGoogle Scholar
  14. Nguyen NT (2010) Micro optofluidic lenses—a review. Biomicrofluidics 4:031501CrossRefGoogle Scholar
  15. Psaltis D, Quake SR, Yang C (2006) Developing optofluidic technology through the fusion of microfluidics and optics. Nature 442(7101):381–386CrossRefGoogle Scholar
  16. Ren H, Liu L (2007) Fringe field effects of finite-size parallel electrodes. Opto-Electronic Engineering 34(7):102–106Google Scholar
  17. Ren L, Escobedo C, Li D (2001) Electroosmotic flow in a microcapillary with one solution displacing another solution. J Colloid Interface Sci 242(1):264–271CrossRefGoogle Scholar
  18. Rosenauer M, Vellekoop MJ (2009) 3D fluidic lens shaping—a multiconvex hydrodynamically adjustable optofluidic microlens. Lab Chip 9(8):1040–1042CrossRefGoogle Scholar
  19. Shi J, Stratton Z, Lin SCS, Huang H, Huang TJ (2010) Tunable optofluidic microlens through active pressure control of an air-liquid interface. Microfluid Nanofluid 9(2–3):313–318CrossRefGoogle Scholar
  20. Sinton D, Li D (2003) Electroosmotic velocity profiles in microchannels. Colloids Surf A 222(1–3):273–283CrossRefGoogle Scholar
  21. Song C, Nguyen NT, Tan SH, Asundi AK (2009) Modelling and optimization of micro optofluidic lenses. Lab Chip 9(9):1178–1184CrossRefGoogle Scholar
  22. Song C, Nguyen NT, Tan SH, Asundi AK (2010) A tuneable micro-optofluidic biconvex lens with mathematically predictable focal length. Microfluid Nanofluid 9:889–896CrossRefGoogle Scholar
  23. Tang SKY, Stan CA, Whitesides GM (2008) Dynamically reconfigurable liquid-core liquid-cladding lens in a microfluidic channel. Lab Chip 8(3):395–401CrossRefGoogle Scholar
  24. Wang C, Gao Y, Nguyen NT, Wong TN, Yang C, Ooi KT (2005) Interface control of pressure-driven two-fluid flow in microchannels using electroosmosis. J Micromech Microeng 15(12):2289–2297CrossRefGoogle Scholar
  25. Weigl BH, Bardell RL, Kesler N, Morris CJ (2001) Lab-on-a-chip sample preparation using laminar fluid diffusion interfaces computational fluid dynamics model results and fluidic verification experiments. Anal Bioanal Chem 371(2):97–105Google Scholar
  26. Wenger J, Gerard D, Aouani H, Rigneault H (2008) Disposable microscope objective lenses for fluorescence correlation spectroscopy using latex microspheres. Anal Chem 80(17):6800–6804CrossRefGoogle Scholar
  27. Wolfe DB, Conroy RS, Garstecki P, Mayers BT, Fischbach MA, Paul KE, Prentiss M, Whitesides GM (2004) Dynamic control of liquid-core/liquid-cladding optical waveguides. Proc Natl Acad Sci USA 101(34):12434–12438CrossRefGoogle Scholar
  28. Wu Z, Nguyen NT (2005) Rapid mixing using two-phase hydraulic focusing in microchannels. Biomed Microdevices 7(1):13–20CrossRefGoogle Scholar
  29. Wu Z, Nguyen NT, Huang X (2004) Nonlinear diffusive mixing in microchannels: theory and experiments. J Micromech Microeng 14(4):604–611CrossRefGoogle Scholar
  30. Yan D, Nguyen NT, Yang C, Huang X (2006) Visualizing the transient electroosmotic flow and measuring the zeta potential of microchannels with a micro-PIV technique. J Chem Phys 124(2):021103CrossRefGoogle Scholar
  31. Yaws CL (2003) Yaws’ handbook of thermodynamic and physical properties of chemical compounds: physical, thermodynamic and transport properties for 5, 000 organic chemical compounds. Knovel, New York, USAGoogle Scholar

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  1. 1.School of Mechanical and Aerospace EngineeringNanyang Technological UniversitySingaporeSingapore

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