Electric Scissors for Precise Generation of Organic Droplets in Microfluidics: A Universal Approach that Goes beyond Surface Wettability

Abstract

Multifarious organic phase droplets have emerged in diverse applications such as material synthesis and biological pharmacy; accordingly, the organic droplet generation demands more on the usability and the controllability. In this article, we demonstrate a universal and simple method to actively generate organic in water (O/W) droplet in a poly(dimethylsiloxane) (PDMS)-based microfluidics device by using both DC and AC electric fields to cut a stable layered flow of the disperse phase into dispersed droplets or liquid slugs in a precise manner. The system demonstrates the feature of ultrafast response and precise control of O/W droplet generation. The biggest advantage of the proposed approach is that it removes the necessity for surface treatment in conventional O/W droplet formation in PDMS microchannels, breaking the limits brought by the surface wettability for the first time and rendering itself to be a universal method for O/W droplet generation. We also explored the breakup of the disperse phase, ...