Imbibition of ''Open Capillary'': Fundamentals and Applications

Control or transportation of small amount of liquid is one of the most important issues in various contexts including medical sciences or pharmaceutical industries to fuel delivery. We studied imbibition of ``open capillary'' both experimentally and theoretically, and found simple scaling laws for both statics and dynamics of the imbibition, similarly as that of imbibition of capillary tubes. Furthermore, we revealed the existence of ``precursor film,'' which developed ahead of the imbibing front, and the dynamics of it is described well by another scaling law for capillary rise in a corner [1]. Then, to show capabilities of open capillaries, we demonstrated two experiments by fabricating micro mixing devices to achieve (1) simultaneous multi-color change of the Bromothymol blue (BTB) solution and (2) expression of the green florescent protein (GFP) [2]. [1] A. Ponomarenko, D. Quere and C. Clanet, J. Fluid Mech., 666, 146 (2011). [2] M. Tani, R. Kawano, K. Kamiya and K. Okumura, Sci. Rep. 5, 10263 (2015).