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Stanford University

Stanford Microfluidics Laboratory

Rapid microfluidic mixers

PI: Juan G. Santiago


Daniel DePonte of the LCLS Sample Environment Department at SLAC National Laboratory

We are developing rapid microfluidic mixers for a variety of assays including studies of the kinetics of protein folding and enzymatic reaction rates. Specifically, we are developing planar microfluidic devices that leverage flow structures for 3D hydrodynamic focusing to decrease the characteristic time scale for mixing while preserving molecule-to-molecule mixing uniformity.
Our group has a strong background in developing rapid micromixers and below we show several examples.

Figure 1: Experimental image of a bulk micromixer. A center fluorescent stream is hydrodynamically focused just upstream of a serpentine channel. Both corner vortices and Dean vortices are exploited to effect rapid stirring of the fluid streams. The channel width and depth in the serpentine region are both 25 microns.

We are also pursuing several designs of lamination mixers. Figure 2 and Figure 3 show examples of these.

Figure 2: Lamination micromixers. (a) Schematic of lamination mixer wherein a center stream is hydrodynamically focused between two symmetric sheath streams initiating mixing and a chemical reaction. (b) Simulation of flow in simple hydrodynamic focusing mixer.

Figure 3: (a) Microfabricated lamination mixer integrated with on-chip filters, flow resistor regions, and a strongly diverging downstream/outlet region. (b) Analysis showing various values of sheath-to-center stream flow rate ratio. Hertzog et al. showed there is an optimum sheath-to-center stream flow rate ratio in lamination mixers.


Hertzog, D.E., X. Michalet, M. Jager, X. Kong, J.G. Santiago, S. Weiss, and O. Bakajin, "Femtomole Mixer for Microsecond Kinetic Studies of Protein Folding," Analytical Chemistry, 76, 24, pp. 7169-7178, 2004.

Hertzog, D.E., B. Ivorra, B. Mohammadi, O. Bakajin, and J.G. Santiago, "Optimization of a Fast Microfluidic Mixer for Studying Protein Folding Kinetics," Analytical Chemistry, 78, 13, pp. 4299-4306, 2006.

Ivorra, B., J.L. Redondo, and A.M. Ramos, and J. G. Santiago, "Sensitivity analysis and study of the mixing uniformity of a microfluidic mixer," Physics of Fluids, 28, 1, pp. 012005, 2016.

Ivorra, B., J.L. Redondo, J. G. Santiago, P.M. Ortigosa, and A.M. Ramos, "Two- and three-dimensional modeling and optimization applied to the design of a fast hydrodynamic focusing microfluidic mixer for protein folding," 25, 032001, Physics of Fluids, 2013

See related publications here