Partners

Abstract:
This report provides practical guidelines for the use of inexpensive electromagnetic valves characterized by large dead volumes (tens to hundreds of μL) for the generation of small (nL) droplets on demand in microfluidic chips. We analyze the role of the ratio of resistances and of the elastic capacitance of the fluidic connectors between the reservoir of the liquid, the valve and the microfluidic chip in the reliable and precise formation of micro droplets on demand. We also demonstrate and examine the use of conventional electromagnetic squeeze valves in the generation of small droplets on demand with a similar set of design rules.

Keywords:
microfluidics, droplets

Abstract:
We demonstrate a new droplet on demand (DOD) technique and an integrated system for scanning of arbitrary combinations of 3 miscible solutions in ∼1.5 μL droplets at 3 Hz. The DOD system uses standard electromagnetic valves that are external to the microfluidic chip. This feature makes up for modularity, simplicity of assembly and compatibility with virtually any microfluidic chip and yields an on-chip footprint of less than 1 mm2. A novel protocol for formation of DOD enables generation of an arbitrarily large range of volumes of droplets at a maximum operational frequency of ∼30 Hz. The integrated system that we demonstrate can be used to scan up to 10000 conditions of chemical and biochemical reactions per hour using ∼10 mL of solutions in total.

Keywords:
microfluidics, automation, droplet on demand, droplet