A millisecond passive micromixer with low flow rate, low sample consumption and easy fabrication

Abstract

Fast mixing of small volumes of solutions in microfluidic devices is essential for an accurate control and observation of the dynamics of a reaction in biological or chemical studies. It is often, however, a challenging task, as the Reynolds number (Re) in microscopic devices is typically < 100. In this report, we detail a novel mixer based on the “staggered herring bone” (SHB) pattern and “split-recombination” strategies with an optimized geometry, the periodic rotation of the flow structure can be controlled and recombined in a way that the vortices and phase shifts of the flow induce intertwined lamellar structures, thus increasing the contact surface and enhancing mixing. The optimization improves the mixing while using a low flow rate, hence a small volume for mixing and moderate pressure drops. The performances of the patterns were first simulated using COMSOL Multiphysics under different operating conditions. The simulation indicates that at very low flow rate (1–12 µL·min−1) and Re (3.3–40), as well as a very small working volume (~ 3 nL), a very good mixing (~ 98%) can be achieved in the ms time range (4.5–78 ms). The most promising design was then visualized experimentally, showing results that are consistent with the outcomes of the simulations. Importantly, the devices were fabricated using a classical soft-lithography method, as opposed to additive manufacturing often used to generate complex mixing structures. This new device minimizes the sample consumption and could therefore be applied for studies using precious samples.

Label-Free Physical Techniques and Methodologies for Proteins Detection in Microfluidic Biosensor Structures

“…In this case, the geometry of the microfluidic system will be more complex and passive, or active separation structures can be added to the chip [ 57 , 58 ]. For labelled techniques, the microfluidic chip can be expanded with microfluidic mixers [ 59 ] to blend the material under test (MUT) with fluorescent components or nanoparticles. In this review, we focus on label-free detection of proteins in biological fluids, so we will not delve into the components for manipulation.…”

Numerical simulation and parameter optimization of micromixer device using fuzzy logic technique

“…Better mixing was achieved in a short distance while using a circular channel with high number of tall wall structure and it act as an obstacles. Y. Liao et al 25 reported a passive micromixer device with staggered herring bone structure and split–recombination microchannel. The mixing efficiency was analysed using a wide range of flow rates, 1–12 μL min −1 , and Reynolds numbers 3.3–40 and they achieved 98% mixing efficiency at 4.5–78 milliseconds.…”

Mixing Enhancement of a Passive Micromixer with Submerged Structures

“…Many micromixers used in the biological and chemical applications operate usually in the range of millisecond mixing time, and the corresponding Reynolds number is less than about 100 [ 28 , 29 , 30 ]. In this range, the mixing mechanism is usually divided into three regimes: molecular dominance, transition, and convection dominance [ 18 , 26 ].…”