Boundary condition induced passive chaotic mixing in straight microchannels

When fluids flow through straight channels sustained turbulence occurs only at high Reynolds numbers [typically [Formula: see text]]. It is difficult to mix multiple flowing a channel in the low number laminar regime [[Formula: text]] because absence of turbulence, mixing between component primarily via slow molecular diffusion process. This Letter reports simple way significantly enhance (in our case text]) passive microfluidic microchannel by introducing asymmetric wetting boundary conditions on floor channel. We show experimentally and numerically that creating carefully chosen two-dimensional hydrophobic slip patterns channels, we can introduce stretching, folding, and/or recirculation fluid volume, essential elements achieve turbulence. also there are two distinctive pathways produce homogeneous microchannels induced inhomogeneity conditions. be achieved either (1) folding twisting volumes, i.e., horse-shoe type transformation map, or (2) chaotic advection, manipulation channels. have shown superposing stretching with optimized terms reducing length, thereby opening up new design opportunities for yet efficient reactors.