A multifunctional microfluidic platform for generation, trapping and release of droplets in a double laminar flow.

Droplet microfluidics, involving micrometer-sized emulsion of droplets is a growing subfield of microfluidics which attracts broad interest due to its application on biological assays. Droplet-based systems have been used as microreactors as well as to encapsulate many biological entities for biomedical and biotechnological applications. Here, a novel microfluidic device is presented for the generation, trapping and release of aqueous including hydrogel droplets in a double laminar oil flow. This platform enables the storage and release of picoliter-sized droplets in two different carrier oils by using hydrodynamic forces without the need of electrical forces or optical actuators. Furthermore, this design allows droplets to be selectively and simultaneously exposed to two different conditions and collected on demand. Successful encapsulation of hepatoma H35 cells was performed on-chip. Viability of cell-laden droplets was performed off-chip to assess the potential applications in 3D encapsulation cell culture and drug discovery assays.