Mixing characteristics in microchannels with biomimetic superhydrophobic (Lotus leaf replica) walls

We demonstrate here the mixing characteristics in microchannels with a biomimetic superhydrophobic (lotus leaf replica) wall. The lotus leaf replica is fabricated using a frugal, yet efficient, double-step soft lithography method. In microchannels with a lotus leaf replica wall, the unidirectional laminar flow pertaining to the low hydrodynamics regime changes into an erratic flow field beyond a critical flow rate. We show here that such lotus leaf replica-induced erratic flow, even for low Reynolds number, can be used for enhanced mixing at the microscale. The enhancement in the mixing is quantified by the reduction in the mixing length in the microchannels with the biomimetic lotus leaf replica wall as compared to identical microchannels with flat walls. We believe that the simple cost-effective methodology for enhancing mixing in microchannels, as demonstrated here, can be integrated into lab-on-a-chip devices, which may be beneficial for applications requiring microscale mixing like DNA sequencing, enzyme reaction, and medical diagnostics.