The role of feedback in microfluidic flow-focusing devices

Matthew T. Sullivan, Howard A. Stone

Research output: Contribution to journalArticlepeer-review

46 Scopus citations


A model was developed for the analysis of steady and unsteady bubble generation frequencies in a microfluidic flow-focusing device. In both cases, the generation frequency depends on the downstream influence of bubbles created by the flow-focusing device, which provides a source of feedback. For steady-state generation of bubbles, this feedback explains the relationships among frequency, gas pressure and liquid flow rate in our experiments as well as gives a physical explanation for previously observed frequency relations. The role of feedback is also exploited to explain unsteady behaviour; we develop a numerical model and analytical expressions that agree with experimental measurements.

Original languageEnglish (US)
Pages (from-to)2131-2143
Number of pages13
JournalPhilosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
Issue number1873
StatePublished - Jun 28 2008
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Engineering
  • General Physics and Astronomy
  • General Mathematics


  • Feedback
  • Flow focusing
  • Microfluidics


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