In this research, a microchannel type mixer composed of micropillars and micronozzles was developed for effective mixing of biochemical samples. To estimate the performance of the newly designed ...micromixer, flow patterns were simulated using computational fluid dynamics (CFD) software. The simulation showed that the mixing efficiency increased from 87.9% to 97.5% as the flow rate varied from 50 to 500 μl/min. When liquid was injected into the fabricated micromixer, it was difficult to prime the microchannel because of the hydrophobicity of the polydimethylsiloxane (PDMS) surface. To overcome this problem, the inside of the micromixer was coated with polyvinylpyrrolidone (PVP). It was found that 0.25 wt.% PVP concentration in the DI water solution is optimal. After appropriate PVP coating, the DI water and the mixture of blue dye and DI water were mixed in the fabricated micromixer and the mixing efficiency was measured. The mixing efficiency increased from 69.7% to 91.7% as the flow rate increased from 50 to 500 μl/min. The new micromixer showed very good mixing performance when the flow rate was over 300 μl/min. Due to the simple structure and uncomplicated fabrication process, the proposed micromixer can be easily integrated into a micro total analysis system (μ-TAS) or lab-on-a-chip (LOC).
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