Y-CHANNEL MICROMIXER EFFICIENCY EVALUATION USING LIF CONFOCAL MICROSCOPE

Abstract

Owing to the extremely small device and velocity scale, mixing in microchannel proceeds very slowly by way of molecular diffusion transport. Thus mixing enhancement becomes a central issue in microfluidics for biomedical and chemical applications. In this work, we perform the approximate optimizations to maximize the mixing efficiency of the Ychannel micromixer. We first consider flow analysis to investigate the effect of obstacle layout and radius on the mixing efficiency using an unstructured grid N-S method including concentration transport phenomena solver. From the simulations, it is shown that the asymmetric layout and radius enlargement of obstacles greatly improves mixing efficiency. Then, optimum design practices are performed using neural network and Sequential Quadratic Programming (SQP) method. In efficient micromixer design, it is essential to evaluate mixing efficiency with good precision. Mixing efficiency for Y-channel micromixer is measured by fluorescence intensity using LIF(Laser Induced Fluorescence) Confocal Microscope. The Ychannel micromixers are fabricated with polydimethylsiloxane (PDMS). Nile Blue A is injected into the micromixer as a fluorescence dye for measuring of fluorescence intensity by He/Ne laser. Throughout the experiments and computer simulation, accurate mixing efficiency evaluation process for a PDMS Y-channel micromixer is established. Keywords: Micromixer, Mixing efficiency, Concentration transport, Optimum design.