Contact Angle Measurement through Liquid Flow in Curved Open Microchannels

Whether liquids in open microchannels show spontaneous capillary flow or not crucially depends on the involved surface energies and the shape of the microchannel. In this study, we present a two-dimensional model based on the Gibb's free energy of a system that predicts the presence of spontaneous capillary flow in open microchannels. We expand our model to include curved microchannels and verify our findings using simulations of a liquid surface with Surface Evolver. Finally, we comment on how these results can be used to measure the liquid contact angle through open capillary flow.