Chaotic Mixing Enhancement in Microfluidic Channels with Time-Varying Geometric Perturbations

Abstract

Microfluidic mixing is difficult because microscale flows remain laminar, which slows homogenization and limits interfacial transport. This is a key issue in lab-on-chip systems, biochemical assays, and compact reaction devices that require rapid mixing. Recent micromixer studies have shown that passive geometric features such as grooves, baffles, and wavy walls can improve mixing by enhancing interface stretching and secondary flow formation. However, most existing designs still rely on static channel geometries, which restrict the flow to a fixed transport pattern. A key gap therefore lies in understanding whether time-varying geometric perturbations can generate stronger chaotic advection than conventional fixed-wall micromixers. This article numerically investigates chaotic mixing in a microfluidic channel with dynamic geometric perturbations and evaluates the effects of perturbation amplitude and actuation frequency on concentration evolution and mixing efficiency. The results show that time-dependent channel deformation improves mixing within an optimal perturbation range, making it a promising strategy for compact high-performance micromixer design.