Suspended microflows between vertical parallel walls

Abstract

Open-surface microfluidic systems, i.e., microflows with a free surface, are finding increasing use in the fields of biotechnology, biology and medicine, especially in the domain of point-of-care and home-care systems. In such systems, the fluids are moved by capillarity and do not require the use of costly and/or bulky pumps, or other actuation systems. Recently, a subcategory of such flows, called “suspended microflows,” has appeared where the liquids flows between vertical walls without supporting walls at the bottom, i.e., surface tension is used to fill and maintain a fluid in microscale structures devoid of a ceiling and floor. The condition for the onset of spontaneous suspended flows has been developed in a preceding article. However, the dynamics of suspended microfluidics has not yet been investigated, and we present here a first analysis of their dynamics. Verifications of the theoretical model have been performed using colored water. Applications to the capillary motion of whole blood and to the motion of polymeric liquids have been done. In particular, we show that capillary filling of a suspended turning channel may be an approach to the realization of in situ giant porous micromembranes.