Dynamics of capillary replacement between two mutually immiscible liquids on an open channel

Capillarity-driven microfluidic devices have been receiving considerable attention in engineering and medical applications [1]. Almost all previous capillarity-driven microfluidic devices involve spontaneous flow of a single liquid. In recent years, the spontaneous replacement between two mutually immiscible liquids has begun to receive attention and is expected to be applied to droplet microfluidics [2]. However, the physical understanding of the replacement is still premature for microfluidic implementation. At the last APS March meeting, we reported the preliminary results of the replacement of aqueous solution with oil on open channels, which were fabricated by a digital light processing 3D printer. This time, we report a quantitative analysis of the dynamics of the capillary replacement using an improved experimental system.

[1] A. Olanrewaju, M. Beaugrand, M. Yafia and D. Juncker, Capillary microfluidics in microchannels: from microfluidic networks to capillaric circuits, Lab Chip 18, 2323 (2018).

[2] E. Berthier, A. M. Dostie, U. N. Lee, J. Berthier, and A. B. Theberge, Open Microfluidic Capillary Systems, Anal. Chem. 91, 8739–8750 (2019).