Passive and active microfluidic separation methods

A variety of microfluidic devices have been used for particle separation. These devices can be categorized as either passive or active. Passive devices use only flow and geometry to generate particle separation. This work reviews the most common passive microfluidic particle separation approaches such as deterministic lateral displacement, pinched flow fractionation, a variety of microfluidic filtration devices, microhydrocyclones, inertial and spiral devices, and viscoelastic flow devices. Active microfluidic devices apply a variety of fields to the microfluidic channels and sometimes pair microfluidic geometries with these fields. Active microfluidic devices reviewed in this work include devices using magnetophoresis, acoustophoresis, and dielectrophoresis. Published applications of these devices are summarized, and the different approaches are briefly compared.