Abstract: In the invention described here, the conventional need for feedback control is eliminated by a passive, open-loop approach using a novel microfluidic droplet generator with a step enhancement. The invented droplet generator yields uniform droplet volumes over a wide range of operating pressures, delivering robust performance at a very low cost. The invention also describes a method of droplet generation whereby the step enhancement improves the performance of any squeeze-mode or dripping-mode droplet generator, including but not limited to bridge-mode and flow-focusing configurations. The performance of the invention is sufficiently stable that it can be operated manually yet still deliver best-in-class microfluidic performance. Thus, not only does the invention greatly simplify and reduce the cost of operation in the laboratory, it opens the possibility of performing precision biology out in the field and off of the electrical grid.

Abstract: Techniques are provided for generating, manipulating, and measuring fluidic droplets in mixed phase systems based on establishing transient continuities between otherwise spatially separated phases. In certain methods of the invention, electrodes in contact with the continuous phases allow electrical monitoring of continuity or proximity of separated phases as a means to characterize droplets. In other methods of the invention, fluidic continuity provides a means for generating droplets, injecting or extracting the contents of droplets, and sorting droplets. Chemical techniques are also provided that use these droplet-based methods, or others, to quantify and identify nucleic acids through incorporation into hydrogel particles. The nucleic acids are entrapped either actively by chemical incorporation during gel polymerization or passively by chain entanglement.