An effective splitting-and-recombination micromixer with self-rotated contact surface for wide Reynolds number range applications

Abstract

It is difficult to mix two liquids on a microfluidic chip because the small dimensions and velocities effectively prevent the turbulence. This paper describes two 2-layer PDMS passive micromixers based on the concept of splitting and recombining the flow that exploits a self-rotated contact surface to increase the concentration gradients to obtain fast and efficient mixing. The designed micromixers were simulated and the mixing performance was assessed. The mixers have shown excellent mixing efficiency over a wide range of Reynolds number. The mixers were reasonably fabricated by multilayer soft lithography, and the experimental measurements were performed to qualify the mixing performance of the realized mixer. The results show that the mixing efficiency for one realized mixer is from 91.8% to 87.7% when the Reynolds number increases from 0.3 to 60, while the corresponding value for another mixer is from 89.4% to 72.9%. It is rather interesting that the main mechanism for the rapid mixing is from diffusion to chaotic advection when the flow rate increases, but the mixing efficiency has not obvious decline. The smart geometry of the mixers with total length of 10.25 mm makes it possible to be integrated with many microfluidic devices for various applications in l-TAS and Lab-on-a-chip systems. V C 2013 AIP Publishing LLC.

Effect of the crossing-structure sequence on mixing performance within three-dimensional micromixers

“…Note that this work is different from our previous work, 26 where the "H" and "O" structures between two neighboring "X" structures are totally different mixing units. Basically speaking, the "H" can recombine two liquid streams in the axial direction and the "O" directs two fluids with less contact.…”

“…26 We first make each PDMS layer with channels by using soft lithography. After treating the required sides of the top and bottom PDMS layers with oxygen plasma, we release a drop of deionized water for lubrication and then match and align the two parts using a "concave and convex" method 27 and bake dry at 60 C for 3 h to bond.…”

A “twisted” microfluidic mixer suitable for a wide range of flow rate applications

“…Many fabricating techniques have been adopted in recent years, which include time-consuming techniques such as photolithography, 27 etching, 28 and the computer numerical control (CNC) micro-milling method 29 . Laser-directed writing is a good tool choice for micromachining, as it provides a simple and inexpensive method of operation 30 .…”

In-plane microvortices micromixer-based AC electrothermal for testing drug induced death of tumor cells

“…14,15 Of the various micromixers reported in the past years, passive mixers, which have included lamination, 16,17 intersecting or disturbing channels, 18,19 and droplet-based platforms, 20,21 have not required energy input or moving parts. Passive mixers are, however, difficult to integrate into organs-on-a-chip systems due to the complexity of their structures.…”