title: The role of feedback in microfluidic flow-focusing devices.
abstract: 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.
authors: School of Engineering and Applied Sciences, Pierce Hall, Harvard University, 29 Oxford Street, Cambridge, MA 02138, USA.
authors: Matthew T
authors: MT
authors: Sullivan
authors: Howard A
authors: HA
authors: Stone