Synthesis of scalable microdroplets with fluid instability of shearing flow in microfluidics

This paper reports a microfluidic reactor for synthesizing micro- and nano-droplets using fluid shearing instability of immiscible flow in microchannels. Three factors, flow rate between the two inputs, spout geometry and surface tension are numerically studied. Based on the simulation, a device with the optimal parameters was fabricated and tested. Both computational fluid dynamics (CFD) simulation results and experimental results suggested that this technique is capable of conveniently controlling the droplets sizes from hundreds of micrometers down to several micrometers or even nanometers. This pilot research offers a proof-of-concept demonstration using instabilities in the microchannels to synthesize large quantity of microdroplets. Although the microdroplets in this study were formed by DI water containing Tween20 and silicon oil, the design with modification could be applied for synthesis of other types of micro- and nano-droplets.