Mixing in axially rotating co-laminar flows

Abstract

We investigate how Diffusion-Induced Lateral Flow (DILF) alters mixing in straight microchannels, a fundamental yet under-explored microfluidic configuration. By employing a spinning disk confocal microscope and finite element numerical simulations, the study provides an in-depth analysis of mixing in co-laminar sucrose/urea streams. Results show that even in density-matched supplies, DILF generates measurable secondary vortices that broaden the interdiffusion zone and raise the cross-section-averaged mixing. Mixing enhancement is most pronounced at intermediate velocities (0.1–0.3 cm s⁻¹) and in channels with aspect ratios > 1, where interface elongation amplifies diffusion. These insights refine design rules for microfluidic assays that rely on either suppressing or exploiting controlled mixing, and lay groundwork for empirical DILF-based mixer models, geometry optimization, and future sheath-flow studies.

The results presented have the potential to significantly improve the accuracy of spatially resolved surface chemistry and biology in microfluidics, thereby advancing microfluidic technology and its applications across various industries.