title: Bubble production mechanism in a microfluidic foam generator.
abstract: We present the design and characterization of a microfluidic bubble generator that has the potential of producing monodisperse bubbles in 256 production channels that can operate in parallel. For a single production channel we demonstrate a production rate of up to 4 kHz with a coefficient of variation of less than 1%. We observe a two-stage bubble production mechanism: initially the gas spreads onto a shallow terrace, and then overflows into a larger foam collection channel; pinning of the liquid-gas meniscus is observed at the terrace edge, the result being an asymmetric pinch-off. A semiempirical physical model predicts the scaling of bubble size with fluid viscosity and gas pressure from measurements of the pinned meniscus width.
authors.affiliation: Université Paris-Est, ESIEE Paris/ESYCOM, Noisy le Grand, 93162 France.
authors.forename: M
authors.initials: M
authors.lastname: Stoffel
authors.forename: S
authors.initials: S
authors.lastname: Wahl
authors.forename: E
authors.initials: E
authors.lastname: Lorenceau
authors.forename: R
authors.initials: R
authors.lastname: Höhler
authors.forename: B
authors.initials: B
authors.lastname: Mercier
authors.forename: D E
authors.initials: DE
authors.lastname: Angelescu