A periodic microfluidic bubbling oscillator: insight into the stability   of two-phase microflows
  This letter describes a periodically oscillating microfoam flow. For constant input parameters, both the produced bubble volume and the flow rate vary over a factor two. We explicit the link between foam topology alternance and flow rate changes, and construct a retroaction model where bubbles still present downstream determine the volume of new bubbles, in agreement with experiment. This gives insight into the various parameters important to maintain monodispersity and at the same time shows a method to achieve controlled polydispersity. 
Jan-Paul Raven (LSP), Philippe Marmottant (LSP)