New regime of droplet generation in a T-shape microfluidic junction

Nathalie Tarchichi (1) , Franck Chollet (1, 2) , Jean-Francois Manceau (1)

1 FEMTO-ST - Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies (UMR 6174)
2 MMC - MicroMachines Centre

We present an experimental study of a new regime of monodisperse micro-droplet generation that we named the balloon regime. A dispersion of oil in water in a T-junction microfluidic system was studied. Several microfluidic devices having different cross-sections of the continuous and the dispersed phases micro-channels were tested. This new regime appears only for low- dispersed phase velocity. The micro-droplet size is mainly related to the geometry of the T-junction micro-channels especially its width and depth, and independent of the continuous and dispersed phases velocities. In our experiments, the velocities of the continuous and the dispersed phases vc and vd respectively, have been varied in a wide range: vc from 0.5 to 500 mm/s, and vd from 0.01 to 30 mm/s. We show that the continuous phase only controls the micro-droplet density, while the dispersed phase linearly changes the frequency of the micro-droplet generation. Another particularity of the present regime, which differentiates it from all other known regimes, is that the micro-droplet retains its circular shape throughout its formation at the T junction, and undergoes no deformation due to the drag forces. We propose a mechanism to explain the formation of microdroplets in this new regime.

Domaines: Micro et nanotechnologies/Microélectronique; Acoustique [physics.class-ph]; Matériaux

Nathalie Tarchichi, Franck Chollet, Jean-Francois Manceau. New regime of droplet generation in a T-shape microfluidic junction. Microfluidics and Nanofluidics, 2013, 14 (1 - 2), pp.45-51. ⟨10.1007/s10404-012-1021-8⟩. ⟨hal-00806454⟩