Abstract

Micromixers are indispensable components in Lab-on-a-Chip and micro total analysis systems (o-TAS). Typical micromixer applications include the mixing of reagents prior to chemical or biological reactions, drug delivery, medical diagnostics through biological sampling, and DNA sequencing or synthesis. The objective of the present investigation is to develop novel passive microfluidic mixers, which integrate mixing mechanisms of lamination and chaotic advection, through planar channel designs. Lamination is incorporated through repeated separation and combination of the mixing streams, while chaotic advection is implemented through serpentine mixing channels and barriers in the flow. The design includes three innovative in-plane on-chip functional micromixers, of channels ranging in width from 0.05 to 0.2 mm, a constant depth of 0.2 mm, and an overall mixer length of 5 mm. An experimental analysis was carried out to evaluate the mixing performance of the designed mixers. The working fluid is distilled water, with one stream mixed with commercial fluorescence dye. Micro Induced Fluorescence (o-IF) is used to quantitatively measure instant whole-field concentration distribution in the channels. Images along the axial length of the micromixers were recorded to quantify the mixing performance, over a Reynolds range of 1 to 100, a Péclet range from 10 3 to 105 , at a Schmidt number in the vicinity of 103 . The mixing performance shows patterns similar to the Taylor dispersion, which consists of both diffusion and convection. Compared to the designs available in literature, the present micromixers have achieved better mixing efficiency up to 95% with a pressure drop of 20 kPa in a mixing length of 5 mm at 1 {601} Re {601} 100. The experimental mixing performance is compared with the simulated results, as well as existing experimental data for different designs within the working Reynolds range. The experimental results show a reasonably good correlation with the simulated results