Institute of Fundamental Technological Research

We present microfluidic modules (traps) that allow us to lock, shift, dose and merge micro-aliquots of liquid precisely. The precision is hard-wired into the geometry of the device: small values of the capillary number guarantee reproducibility of operation over a range of rates of flow that need not be controlled precisely. The modules can be integrated into systems that perform complicated protocols on micro-droplets while not requiring precision in forcing the flow.

microfluidics, droplets

We introduce a novel type of droplet generator that produces droplets of a volume set by the geometry of the droplet generator and not by the flow rates of the liquids. The generator consists of a classic T-junction with a bypass channel. This bypass directs the continuous fluid around the forming droplets, so that they can fill the space between the inlet of the dispersed phase and the exit of the bypass without breaking. Once filled, the dispersed phase blocks the exit of the bypass and is squeezed by the continuous fluid and broken off from the junction. We demonstrate the fixed-volume droplet generator for (i) the formation of monodisperse droplets from a source of varying flow rates, (ii) the formation of monodisperse droplets containing a gradation of solute concentration, and (iii) the parallel production of monodisperse droplets.

droplet generator, droplets, microfluidics

Techniques operating on droplets and treating them as single reactors are very promising due to their advantage: i) lack of dispersion, ii) fast mixing, iii) superior control on kinetics of reactions, iv) easy to paralelization v) small volume The challenge is to control the size and the content of each droplet simultaneously.
We present concept of microfluidic modules that taking advantage of the capillary back pressure allow to trap, dose and realize precise portion of liquid. The precision is encrypted in the geometry of the device and large mismatch of shear stresses and capillary forces. This mismatch guaranties reproducibility over a wide range of rates of flow that need not be controlled precisely. We also demonstrate that these modules allow to built systems that perform complicated protocols precisely while nor precise control.

microfluidics, droplets