Two-dimensional model of imbibition into paper-based networks using Richards' equation

The prediction of the imbibition into two-dimensional geometries is extremely important to develop new paper-based microfluidics design principles. In this regard, a two-dimensional model using Richard's equation, which has been extensively applied in soil mechanics, is applied in this work to model the imbibition into paper-based networks. Compared to capillary-based models, the developed model is capable of predicting the imbibition into two-dimensional domains. The numerical solution of the proposed model shows a good agreement with the experimental measurements of water imbibition into different chromatography paper-based designs. It is expected that this framework can be applied to develop new design rules for controlling the flow in paper-based microfluidics devices.