Mixing in Microfluidics
Various applications require a controlled mixing of multiple fluids in microfluidic devices. However, microfluidic mixing presents a challenge due to the laminar flow regime in microchannels, which result from low Reynolds numbers determined by the channel dimensions, flow velocity, and kinetic viscosity of the solution. For example, the dominant mixing mechanism would be molecular diffusion in a simple Y-shaped junction of two mixing fluids
Most mixing techniques focus on spatial mixing, i.e., two inlet fluids with constant volume flow are combined and mixed into one outlet fluid. Here, passive mixing methods of channel designs have been used, e.g., flow channel geometries with slanted wells or ridges, varying channel geometry, changing channel topologies, and channel surface modification.