Ultrasound-actuated microfluidic flow focusing allows control of bubble size and production rate

Microfluidic flow focusing is a promising tool for the creation of monodisperse microbubbles, such as ultrasound contrast agents. However, industrial-scale bubble production remains elusive due to a lack of control over bubble size and production rate in devices with paralellized flow-focusing nozzles. In this paper we introduce a way of fine-tuning the production rate and bubble size through the use of ultrasound excitation. We show that the production rate can be locked to the ultrasound driving frequency and that the bubble size depends on the acoustic driving pressure. These results may be exploited in particular to increase monodispersity in parallelized systems.