Chaotic mixing enhancement in electro-osmotic flows by random period modulation

In this Letter we report a method for enhancing mixing of a passive tracer in an electro-osmotic flow in a rectangular microchannel. A time-periodic electric field across the microchannel, filled with an electrolyte solution, is applied in order to realize a well-mixed state. A random perturbation to the time-periodic electric field is introduced in order to break the invariant tori of the system and achieve better mixing results. It is shown that under such period-modulation the enhancement effect increases with the strength of the modulation, and it is much reduced as diffusion is increased.