DEP actuation of emulsion jets and dispensing of sub-nanoliter emulsion droplets

Abstract

Liquid Dielectrophoresis (L-DEP) has been successfully leveraged at microscopic scales and shown to provide a controllable means of on-chip precision dispensing and manipulation of sub-nanoliter single emulsion droplets. In this paper, we report on the dynamics of a DEP actuated emulsion jet prior to break-up and compare its characteristic behavior based on the lumped parameter model of Jones et al. (R. Ahmed and T. B. Jones, J. Micromech. Microeng., 2007, 17, 1052). Furthermore, features and aspects of these emulsion jets, their break-up and formation of sub-nanoliter emulsion droplets is studied in further detail. Applications of the proposed scheme in dispensing encapsulated sub-nanoliter droplets is envisioned in various fields including microTAS, on-chip handling and storage of cells and other biological samples for longer duration in controlled environments as well as solving the more general encapsulation issues in surface microfluidic devices. Scalability of the proposed scheme is shown by producing controlled sample-oil single emulsion droplets (aqueous samples in oil) in the range of 50-400 picoliters.