Passive microfluidic device for submillisecond mixing

Abstract

We report the investigation of a novel microfluidic mixing device to achieve submillisecond mixing. The micromixer combines two fluid streams of several microliters per second into a mixing compartment integrated with two T-type premixers and 4 butterfly-shaped in-channel mixing elements. We have employed three dimensional fluidic simulations to evaluate the mixing efficiency, and have constructed physical devices utilizing conventional microfabrication techniques. The simulation indicated thorough mixing at flow rate as low as 6 µL/s. The corresponding mean residence time is 0.44 ms for 90% of the particles simulated, or 0.49 ms for 95% of the particles simulated, respectively. The mixing efficiency of the physical device was also evaluated using fluorescein dye solutions and FluoSphere-red nanoparticles suspensions. The constructed micromixers achieved thorough mixing at the same flow rate of 6 µL/s, with the mixing indices of 96% ± 1%, and 98% ± 1% for the dye and the nanoparticle, respectively. The experimental results are consistent with the simulation data. The device demonstrated promising capabilities for time resolved studies for macromolecular dynamics of biological macromolecules.

Mixing performance of unbalanced split and recombine micomixers with circular and rhombic sub-channels

“…Planar split and recombine micromixers have been studied from simplest design with multiple streams [23][24][25][26][27][28]. Bessoth et al [23] reported a design of planar split and recombine micromixer with a total of 32 streams, which showed efficient mixing.…”

“…The mixing efficiency was increased by providing constriction to the flow in the zone of split and recombine with the sub-channels of rhombic shape [26,27]. The design of the split channels was modified to butterfly shaped with sharp folded channels for providing stirring action to mix the fluids with equal width of the two split channels [28]. These were few reported techniques to enhance mixing performance of the planar split and recombine micromixers.…”

Gas-assisted annular microsprayer for sample preparation for time-resolved cryo-electron microscopy

“…The previous 2D microspray nozzle [10] consisted of in-plane shallow microfluidic channels with rectangular cross-sections, two of which carried gas and sandwiched a third channel that transported the aqueous reaction mixture. This type of in-plane nozzle structure induces significant gas resistance inside the gas channel, and limits the mass flow rate of the gas available for liquid atomization.…”

Experimental investigation of a scaled-up passive micromixer with uneven interdigital inlet and teardrop obstruction elements

“…Nguyen et al (2008) investigated the mixing efficiency of a micromixer with square obstructions in a square-wave channel, and Chung and Shih (2007) studied a three-rhombus micromixer with two constriction elements. Ansari et al (2010) examined curved subchannels of uneven width, and Lu et al (2010) investigated a micromixer with two tee-inlets and four butterfly-shaped mixing elements. Such designs typically provoke mixing via vortex formation, contrary to designs which employ numerous smaller obstacles in the mixing channel.…”

“…For the obstruction-based mixer of Bhagat et al (2007), the figure shows an increased degree of mixing at lower Reynolds number, as the device is diffusion dominant. As seen in the figure, the design of Lu et al (2010), which makes use of a 4 lamellae inlet and butterfly-shaped mixing elements, shows a short comparable mixing length and high degree of mixing, particularly at higher Reynolds numbers, such that the device is advection based.…”