Analysis of Proportional Microfluidic Mixing in a Sequential Injection Micro-Mixer

Abstract

In this study, external electric potentials with high (5Hz) and low (0.5Hz) switching frequencies are applied to induce electro-osmotic flow in micro-mixers to achieve sequential segment injection. A micro-mixer arranged in asterisk-patterns combined with an expansion chamber is designed to deliver a certain quantity of solution into the micro-mixer and achieve rapid proportional mixing. The main purpose of the expansion chamber is to achieve highly efficient mixing by increasing the contact area that produces the diffusion effect. The induced electro-osmitic flows in the microchannels were investigated by numerical simulations in the study. The asterisk-pattern micro-mixer can reduce the examination time by allowing the sequential segment injection of three solutions into the micro-channel. In this study, the micro-mixers are subjected to low and high switching frequencies to investigate the mixing efficiencies of the mixers. The simulation results show that suitable restraint electric field intensities are required to form the sequential segment solutions into approximate rectangular shapes in the micro-channel. Furthermore, the high switching frequency allows both patterns to achieve better mixing efficiencies than with the low switching frequency.