Oscillating Air-Liquid Interface: A Novel Approach for In-channel Microfluidic Mixing

Microfluidic mixing is a vital process in lab-on-achip technology. The precise and controllable mixing of the samples is required for high specificity, throughput and low reagent consumption.This study offers a novel strategy to enhance the mixing efficiency in microfluidic devices using air-liquid interface (ALI) oscillations combined with ridge structures. Oscillations of up to 7 micrometers are induced by a piezoelectric transducer, significantly improving mixing performance, with the Relative Mixing Index (RMI) increasing from 0.8109 to 0.9292. The ridge design further enhances mixing by generating micro-vortices, working synergistically with the ALI oscillations.