title: Hydrodynamic control of droplet division in bifurcating microchannel and its application to particle synthesis.
abstract: We describe herein a microfluidic system for active and precise control of droplet division at a bifurcation point in a microchannel. Water-in-oil or oil-in-water droplets, which were initially formed at a T-junction, were introduced into the bifurcation point, and then divided into two daughter droplets. By continuously introducing 'tuning flow' into the downstream of one of the branch channels, and by controlling the flow rates distributed into the two branch channels, the sizes of the daughter droplets could be precisely tuned. The ratio of the volumetric flow rates into the branch channels was estimated by regarding the microchannel network as a resistive circuit. In addition, we performed synthesis of monodispersed polymer particles with controlled sizes utilizing the presented system. The ability to hydrodynamically control the droplet sizes will open new possibilities not only for producing useful emulsions, but also for conducting controlled chemical and biochemical reactions in a confined space.
authors.affiliation: Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Masumi
authors.initials: M
authors.lastname: Yamada
authors.forename: Saki
authors.initials: S
authors.lastname: Doi
authors.forename: Hirosuke
authors.initials: H
authors.lastname: Maenaka
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yasuda
authors.forename: Minoru
authors.initials: M
authors.lastname: Seki