Regensburg 2007 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 25: Micro and Nano Fluidics III: Lab-on-Chip Geometries

CPP 25.5: Talk

Thursday, March 29, 2007, 18:30–18:45, H37

Juggling with droplets: manipulation of monodisperse gel emulsions in microchannels — •Enkhtuul Surenjav, Craig Priest, Stephan Herminghaus, and Ralf Seemann — Max-Planck Institute for Dynamics and Self-Organization, Bunsenstraße 10, D-37073, Göttingen, Germany

Emulsions with a continuous phase volume fraction of a few percent only are called gel emulsions. These emulsions are topologically analogous to foam and the monodisperse compartments (droplets) assemble into well-defined arrangements. Hence, the position of a single droplet within an ensemble of droplets is fully determined while being transported through microfluidic channels. We studied the online generation, organization, and manipulation of monodisperse gel emulsions using a variety of microchannel geometries. In particular, the topological change between a zigzag structure and a bamboo structure is considered. "Passive" reorganization, based on fixed channel geometries, can be supplemented by "active" manipulation of an incorporated ferrofluid phase. A ferromagnetic continuous phase facilitates reorganization of liquid compartments on demand using an electromagnetic trigger. Moreover, coalescence between adjacent compartments of a well-defined gel emulsion can be induced via spinodal instability of their lamellae when applying an electrical potential of a few volts across a lamella. We anticipate that microfluidic processing of compartmented liquid will be well-suited for applications in combinatorial chemistry, DNA sequencing, drug screening and protein crystallizations.