(98a) Mixing Efficiency in a Simple, Continuous, Laminar-Flow Microdevice Using Computational and Experimental Approaches

Microfluidic devices are small-scale designed to mix two miscible fluids at the microscale level achieve in order to promote fluid mixing and blending by increasing the contact area between the mixing species. In a number of cases these devices use complex 2D or 3D architectures, including multiple splitting, recombining, or rotating channels incorporating structures with twists, embedded barriers, or staggered herringbone structures. These devices can be complex and expensive to fabricate. In this work, a simple but effective micromixer device was assembled to obtain a microfluidic mixer that is easy to fabricate, inexpensive, and readily built in most laboratories without the need for dedicated personnel, extensive training, and dedicated and costly fabrication equipment. To achieve this goal, serpentine micromixers were developed, built, experimentally tested, and computationally analyzed using a lamination-based assembly that can be obtained by using simple tools and supplies available in non-microdevice dedicated laboratories. A fluorescence imaging technique was then used to quantify the mixing effectiveness of these devices. Computational Fluid Dynamics (CFD) modeling of the same devices using a commercially available software (COMSOL) was conducted to both validate the computational approach and to corroborate the experimental results. The computational results were found to be in excellent agreement with the experimental data and showed that the serpentine micromixer can achieve significant levels of mixing efficiency. In addition, different modified versions of the same basic serpentine design were analyzed using CFD in order to determine which systems would result in improved mixing efficiency. Finally, computational results for a straight microfluidic channel were separately obtained in order to quantify the increase in mixing efficiency produced by the serpentine design with respect to a similar channel of the same length. These computational results were also compared with previous theoretical predictions for straight channels and were in excellent agreement with them.