Microfluidic four-roll mill for all flow types

A microfluidic four-roll mill device that can cover the entire spectrum of flow types including purely rotational flow was designed using pseudo-three-dimensional simulations. In experiments using high aspect ratio devices etched in silicon, the authors observed the whole range of flow type by changing only the flow rate ratio. This microfluidic four-roll mill device can be applied to examining microdrop deformation and the dynamics of single molecules in a mixed flow or to enhancing mixing efficiency by sinusoidal changes of the inlet flow rate.