Design of a Hybrid Active and Passive Efficient Micromixer for 3D Printed Microfluidics

Abstract

Mixing efficiency is one of the most important factors in stabilizing the final diffusion concentration inside a microfluidic Lab-on-a-chip (LOC). In this study, an examination of the combinational effects of active (electro-osmotic) and passive (barrier) mixing are investigated using finite element analysis. Mixing time and mixing length are the two key performance factors for designing a mixer. Our investigation presents an approach for reducing mixing time and length. We investigated mixing sub-factor such as: excitation voltage, electrode size, excitation frequency and electrode amount for efficient mixing. We simultaneously tested passive mixing factors such as: barrier shape, size and amount. Our result shows that among different barrier shapes, square barriers provided the best mixing. It was also noted that barrier size, within the dimensions we tested, did not vary the mixing output significantly. In the active mixing trials, the input voltage and frequencies were tested. Reducing excitation voltage reduces concentration dilution and the frequency had a parabolic relationship with concentration. Mixing efficiency is also related to the amount of electrodes present. The competing values for each sub-factor are plotted against each other to compare the cross effects on mixing efficiency and to find best geometric and excitation parameters. The optimal hybrid mixer presented in this paper can enable further development of next generation lab-on-chip devices based on 3D microfluidics.