Two-dimensional flow dynamics in digital microfluidic systems

A two-dimensional model for the fluid flow in a digital microfluidic system is introduced, and the results are compared to experimental data. Resistive flow effects based upon contact line forces, filler effects and shear forces are applied in the model. It is found that the induced vertical velocity components are critical to the overall motion, as velocity and pressure gradients, together with microdroplet surface deformations, can limit the desired horizontal velocity. These effects are particularly important for digital microfluidic systems characterized by higher Reynolds numbers.