Rapid generation of small water-water droplets at the interface of a jet flowing at high speed

Abstract

All-aqueous droplets have promising potential in biomedical applications such as enzyme encapsulation. However, it remains difficult to generate water-water droplets with a narrow size distribution, a high degree of control over droplet size and a high generation frequency. We propose a robust method to generate all-aqueous droplets of a relatively small size (~ 10 microns), at an ultra-high rate (several kilohertz), and with a high size uniformity (c.v. less than 1%). Our technique is based on the shearing of the droplet phase off of the interface of a jet, which is flowing at a significantly higher speed than the continuous phase. We anticipate that by generating size controllable water-water droplets in a rapid and scalable manner, this technique will inspire new application of all-aqueous emulsion droplets.