Valve-based flow focusing for drop formation

Valve-based flow focusing for drop formation

Picoliter drops made in microfluidic devices can serve as individual compartments for chemical reactions and can be processed at kilohertz rates with high precision. This combination of speed and containment is very useful for highthroughput screening, for discovering novel drugs, for sorting analytes and worms, and for directed evolution of enzymes and cells. For applications in microfluidics,...

Formation of Tunable, Emulsion Micro-Droplets Utilizing Flow-Focusing Channels and a Normally-Closed Micro-Valve

A mono-dispersed emulsion is of great significance in many chemical, biomedical and industrial applications. The current study reports a new microfluidic chip capable of forming tunable micro-droplets in liquids for emulsification applications. It can precisely generate size-tunable, uniform droplets using flow-focusing channels and a normally-closed valve, which is opened by a pneumatic suctio...

Isoelectric focusing in a drop.

A novel approach to molecular separations is investigated using a technique termed droplet-based isoelectric focusing. Drops are manipulated discretely on a superhydrophobic surface, subjected to low voltages for isoelectric focusing, and split-resulting in a preparative separation. A universal indicator dye demonstrates the generation of stable, reversible pH gradients (3-10) in ampholyte buff...

Microfluidic flow focusing: drop size and scaling in pressure versus flow-rate-driven pumping.

We experimentally study the production of micrometer-sized droplets using microfluidic technology and a flow-focusing geometry. Two distinct methods of flow control are compared: (i) control of the flow rates of the two phases and (ii) control of the inlet pressures of the two phases. In each type of experiment, the drop size l, velocity U and production frequency f are measured and compared as...

Formation of dispersions using ‘‘flow focusing’’ in microchannels