Microfluidics and Nanofluidics

, Volume 3, Issue 1, pp 19–25 | Cite as

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

Research Paper


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 



We acknowledge Lung-Hsin Hung and Wei-Yu Tseng, graduate students in the BioMINT lab, UC Irvine for helping with the fabrication, Daphne Collins, Brain Imaging Center, UCI for preliminary image analysis and start up funding from UCI. Startup funding from UC Irvine.


  1. Anna SL, Bontoux N, Stone HA (2003) Formation of dispersions using “flow focusing” in microchannels. Appl Phys Lett 82(3):364–366CrossRefGoogle Scholar
  2. Bringer MR, Gerdts CJ, Song H, Tice JD, Ismagilov RF (2004) Microfluidic systems for chemical kinetics that rely on chaotic mixing in droplets. Philos T Roy Soc A 362(1818):1087–1104CrossRefGoogle Scholar
  3. Chao W-C, Collins J, Bachman M, Li GP, Lee AP (2004) Droplet arrays in microfluidic channels for combinatorial screening assays. Hilton Head 2004: A solid state sensor, Actuator and Microsystems Workshop, Hilton HeadGoogle Scholar
  4. Chen DL, Gerdts CJ, Ismagilov RF (2005) Using microfluidics to observe the effect of mixing on nucleation of protein crystals. J Am Chem Soc 127(27):9672–9673CrossRefGoogle Scholar
  5. Collins J, Lee AP (2004) Detection and analysis of high speed droplet generation in a microfluidic device. ASME International Mechanical Engineering Congress and R&D Expo 2004, Anaheim, CA, ASMEGoogle Scholar
  6. Dendukuri D, Tsoi K, Hatton TA, Doyle PS (2005) Controlled synthesis of nonspherical microparticles using microfluidics. Langmuir 21(6):2113–2116CrossRefGoogle Scholar
  7. Drenckhan W, Cox SJ, Delaney G, Holste H, Weaire D, Kern N (2005) Rheology of ordered foams—on the way to Discrete microfluidics. Colloid Surface A 263(1–3):52–64CrossRefGoogle Scholar
  8. Duffy DC, McDonald JC, Schueller OJA, Whitesides GM (1998) Rapid prototyping of microfluidic systems in poly(dimethylsiloxane). Anal Chem 70:4974–4984CrossRefGoogle Scholar
  9. Fouillet Y, Achard JL (2004) Digital microfluidic and biotechnology. Cr Phys 5(5):577–588CrossRefGoogle Scholar
  10. Gneist G, Bart HJ (2002) Droplet formation in liquid/liquid systems using high frequency AC fields. Chem Eng Technol 25(2):129–133CrossRefGoogle Scholar
  11. Govor LV, Parisi J, Bauer GH, Reiter G (2005) Instability and droplet formation in evaporating thin films of a binary solution. Phys Rev E 71(5):051603CrossRefGoogle Scholar
  12. de Heij B, Daub M, Gutmann O, Niekrawietz R, Sandmaier H, Zengerle R (2004) Highly parallel dispensing of chemical and biological reagents. Anal Bioanal Chem 378(1):119–122CrossRefGoogle Scholar
  13. Kohler JM, Kirner T (2005) Nanoliter segment formation in micro fluid devices for chemical and biological micro serial flow processes in dependence on flow rate and viscosity. Sensor Actuat a-Phys 119(1):19–27CrossRefGoogle Scholar
  14. Kuksenok O, Jasnow D, Yeomans J, Balazs AC (2003) Periodic droplet formation in chemically patterned microchannels. Phys Rev Lett 91(10):108303CrossRefGoogle Scholar
  15. Lyuksyutov IF, Naugle DG, Rathnayaka KDD (2004) On-chip manipulation of levitated femtodroplets. Appl Phys Lett 85(10):1817–1819CrossRefGoogle Scholar
  16. Neugebauer S, Evans SR, Aguilar ZP, Mosbach M, Fritsch I, Schuhmann W (2004) Analysis in ultrasmall volumes: microdispensing of picoliter droplets and analysis without protection from evaporation. Anal Chem 76(2):458–463CrossRefGoogle Scholar
  17. Nguyen N-T, Lassemono S, Chollet FA (2006) Optical detection for droplet size control in microfluidic droplet-based analysis systems. Sens Actuators B: in print. DOI:10.1016/j.snb.2005.12.010Google Scholar
  18. Nisisako T, Torii T, Higuchi T (2002) Droplet formation in a microchannel network. Lab Chip 2(1):24–26CrossRefGoogle Scholar
  19. Omrane A, Santesson S, Alden M, Nilsson S (2004) Laser techniques in acoustically levitated micro droplets. Lab Chip 4(4):287–291CrossRefGoogle Scholar
  20. Phou T, Jugieu D, Gue AM (2003) Design and realization of an ejectors micro-array for in-situ oligonucleotide synthesis on DNA chip. Houille Blanche (5):97–103Google Scholar
  21. Seo M, Nie ZH, Xu SQ, Lewis PC, Kumacheva E (2005) Microfluidics: from dynamic lattices to periodic arrays of polymer disks. Langmuir 21(11):4773–4775CrossRefGoogle Scholar
  22. Srinivasan V, Pamula VK, Fair RB (2004) Droplet-based microfluidic lab-on-a-chip for glucose detection. Anal Chim Acta 507(1):145–150CrossRefGoogle Scholar
  23. Sugiura S, Nakajima M, Iwamoto S, Seki M (2001) Interfacial tension driven monodispersed droplet formation from microfabricated channel array. Langmuir 17(18):5562–5566CrossRefGoogle Scholar
  24. Sugiura S, Oda T, Izumida Y, Aoyagi Y, Satake M, Ochiai A, Ohkohchi N, Nakajima M (2005) Size control of calcium alginate beads containing living cells using micro-nozzle array. Biomaterials 26(16):3327–3331CrossRefGoogle Scholar
  25. Tan Y-C, Cristini V, Lee AP (2006) Monodispersed microfluidic droplet generation by shear focusing microfluidic device. Sens Actuators B 114(1):350–356CrossRefGoogle Scholar
  26. Tice JD, Song H, Lyon AD, Ismagilov RF (2003) Formation of droplets and mixing in multiphase microfluidics at low values of the Reynolds and the capillary numbers. Langmuir 19(22):9127–9133CrossRefGoogle Scholar
  27. Tsuru T, Tamiya KI, Nishikata A (2004) Formation and growth of micro-droplets during the initial stage of atmospheric corrosion. Electrochim Acta 49(17–18):2709–2715CrossRefGoogle Scholar
  28. Wheeler AR, Moon H, Kim CJ, Loo JA, Garrell RL (2004) Electrowetting-based microfluidics for analysis of peptides and proteins by matrix-assisted laser desorption/ionization mass spectrometry. Anal Chem 76(16):4833–4838CrossRefGoogle Scholar
  29. Wheeler AR, Moon H, Bird CA, Loo RRO, Kim CJ, Loo JA, Garrell RL (2005) Digital microfluidics with in-line sample purification for proteomics analyses with MALDI-MS. Anal Chem 77(2):534–540CrossRefGoogle Scholar
  30. Yogi O, Kawakami T, Yamauchi M, Ye JY, Ishikawa M (2001) On-demand droplet spotter for preparing pico- to femtoliter droplets on surfaces. Anal Chem 73(8):1896–1902CrossRefGoogle Scholar

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

Personalised recommendations