title: Microfluidic assembly of Janus-like dimer capsules.
abstract: We describe the microfluidic assembly of soft dimer capsules by the fusion of individual capsules with distinct properties. Microscale aqueous droplets bearing the biopolymer chitosan are generated in situ within a chip and, as they travel downsteam, pairs of droplets are made to undergo controlled cross-linking and coalescence (due to a channel expansion) to form stable dimers. These dimers are very much like Janus particles: the size, shape, and functionality of each individual lobe within the dimer can be precisely controlled. Dimers with one lobe much shorter than the other resemble a bowling pin in their overall morphology, while dimers with nearly equal-sized lobes are akin to a snowman. To illustrate the diverse functionalities possible, we have prepared dimers wherein one lobe encapsulates paramagnetic Fe2O3 nanoparticles. The resulting dimers undergo controlled rotation in an external rotating magnetic field, much like a magnetic stir bar. The overall approach described here is simple and versatile: it can be easily adapted in numerous ways to produce soft structures with designed properties.
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Maryland , College Park, Maryland 20742, United States.
authors.forename: Annie Xi
authors.initials: AX
authors.lastname: Lu
authors.forename: Kunqiang
authors.initials: K
authors.lastname: Jiang
authors.forename: Don L
authors.initials: DL
authors.lastname: DeVoe
authors.forename: Srinivasa R
authors.initials: SR
authors.lastname: Raghavan