Generation of Micron-Size All-Aqueous emulsions by interfacial folding

Abstract

All-aqueous system has promising bio- and cyto-compatibility and hence is widely used in biotechnology and biomaterials.1,2 This has fostered efforts to generate all-aqueous emulsions with controlled size.3-6 However, current techniques are often limited by low droplet generation frequency, relatively large size of droplets and high size polydispersity. We present a microfluidic technique to generate all-aqueous emulsions from interfacial folding. We perturb a water-water jet in a microfluidic channel. Due to the low interfacial tension, the interface is folded and aqueous droplets of the outer phase are sheared off from the interface. We regulate the droplet size and generation rate by controlling the perturbation amplitude and frequency. The droplets are of micron-size (O(1) μm), generated at a high throughput (O(102-103) Hz) and with low size polydispersity (c.v. 5%). The all-aqueous droplets, added with suitable stabilizers, could serve as the building block of new bio- or cyto-mimetic materials.