Microfluidic rectifier
Photographs of microfluidic rectifier and close-ups of its different parts. Fluidic rectifier is channel of a special shape, which acts as a diode. At the same applied pressure, flux of fluid through the channel is different for flows in opposite directions. A macroscopic fluidic rectifier was patented in 1920 by Tesla. It operated in non-linear regime at high Reynolds numbers, Re. The microfluidic rectifier, shown at the top, works with elastic polymer solutions at low Re, but high Weissenberg number, Wi. The active rectifying channel is a chain of triangular segments in the middle, also shown at the bottom left. All the rest of the channels are auxiliary and enable measuring dependence of flux in the active channel of on pressure applied to it in the both directions. Maybe somewhat against intuition, the flow resistance at high Wi is lower in the direction from left to right. The maximal direction dependent difference in fluxes for the same applied pressure reaches a factor of almost two.