Electrified jets in the presence of a co-flowing liquid - A route to fine emulsions

Georgia Tech Research Corporation, Atlanta GA

Investigators

Abstract

The precision manipulation of streams of fluids with microfluidic devices is revolutionizing many fluid-based technologies. In particular, microfluidics offers unprecedented possibilities for controlled mixing of components to generate drops as templates for novel materials. However, despite the promise of these small-scale devices, the droplets and particle sizes that can be produced are rarely smaller than ~10 micrometers in diameter; this excludes materials in the colloidal domain of great fundamental and technological value. The objective of this project is to effectively couple hydrodynamic and electric forces to generate, in steady-state, drops with sizes that can be tuned from well below to well above the micron scale. The intellectual merit resides in understanding and experimentally controlling the mechanism by which drops are generated in capillary-based microfluidic devices in the presence of electric fields. In particular, this research will elucidate how electric fields affect drop formation in co-flowing liquid streams, where one liquid is injected through a capillary tube into another immiscible liquid, and focus on the fundamental fluid mechanics controlling the process. The project involves the study of jet formation under the action of electric fields and the study of the hydrodynamic stability of these jets against the growth of both varicose, axisymmetric perturbations and off-axis, lateral instabilities. The broader impact of the project is provided by the use of this fundamental knowledge to generate monodisperse emulsions with an unprecedented tunability of the drop size; this is industrially relevant, as drops are used in many everyday products, including food, cosmetic, heath and personal care products. Through the involvement of industrial partners we will additionally enhance the education of undergraduate students, who will not only learn how to use technologically relevant instrumentation and acquire a deep fundamental understanding of the relevant fluid mechanics involved in drop formation processes, but who will also broaden their training with these interactions. Additionally, the visual appeal of the research we plan to conduct will aid the preparation of new courses and lectures.