Traditional methods of foam generation (beating, whipping,
evolution of dissolved gas) result in polydisperse foam. To achieve
monodispersity a nozzle (such as that of a syringe) may be used to
issue bubbles at a time below a liquid surface.1 It has often been
necessary to maintain a slow rate of generation, as the process of
bubble detachment can become chaotic at higher rates.12
Recently this technique has been enhanced by so-called
microfluidic flow focusing,13–15 to produce a rapid stream of
comparatively small bubbles. We have used this method to create
samples of foams, consisting of equal sized bubbles where we
varied the diameter between 100 to 500 mm.