Systems and methods for microfluidic particle selection, encapsulation, and injection using surface acoustic waves

Abstract

This relates to acoustic microfluidic systems that can generate emulsions/droplets or encapsulate particles of interest (including mammalian cells, bacteria cells, or other cells) into droplets upon detection of the particles of interest flowing in a stream of particles. The systems operate on the detect/decide/deflect principle wherein the deflection step, in a single operation, not only deflects particles of interest from a stream of particles but also encapsulates the particles of interest in an emulsion droplet. The microfluidic systems have an abrupt transition in the channel geometry from a shorter channel to a taller channel (i.e., in the shape of a 'step') to break the stream of the dispersed phase into a droplet upon acoustic actuation. When there is no acoustic wave present, no droplets/emulsions are generated and the stream of particles proceeds uninterrupted. The rapid actuation and post-actuation recovery employed by the microfluidic systems taught herein ensure that the vast majority of selected particles are properly deflected, that few or no empty droplets are produced, and that total throughput remains high.