Microfluidics technology has been applied to different chemical and biological applications of lab-on-a-chip (LOC) devices including medical diagnostics, drug development etc. A LOC device needs to be compact, miniatured requiring a small concentration of reagents for analysis. Microfluidic devices range from ten to several hundred micrometers in characteristic dimension. These devices are formed by the integration of micropumps, microvalves, micromixer, micro-separator and micro-reactors.¹ In most processes there is need of two or more fluids mixing for example blood solution with the biomarkers that are immersed in a buffer solution. Therefore, micromixer is an essential component of the LOC. Due to very wide range of micromixers applications in chemical reactions, dispersions, and emulsification, it is important for the mixer to have superior mixing efficiency. The difficulty in achieving sufficient mixing in a microfluidic device results from laminar flows that can be explained by low Reynolds number; sometimes its value is less than 1.^2,3 The flow is laminar and there is lack of turbulence which makes molecular diffusion the primary mechanism for mixing. High mixing efficiency cannot be achieved with the help of only diffusion. During the process of mixing by diffusion, low molecular weight molecules mix in a shorter duration whereas, molecules with high molecular weights such as nucleic acids, proteins not only require a greater length of microchannel but also more time duration (minutes to hours) to ensure complete mixing.⁴ Thus mixing of fluids in these devices at low Reynolds number is a challenge because of very short channels or chamber for fluid flow and controlled time for mixing process to take place. Mixing performance can be enhanced with the help of designs structure modification or applying some external force.⁵

中文翻译：

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使用Taguchi方法的主动和被动微型混合器的最佳参数混合分析

微流体技术已应用于芯片实验室（LOC）设备的不同化学和生物学应用，包括医学诊断，药物开发等。LOC设备需要紧凑，小型化，需要少量试剂进行分析。微流体装置的特征尺寸范围为十至数百微米。这些装置是通过集成微型泵，微型阀，微型混合器，微型分离器和微型反应器而形成的。^1个在大多数过程中，需要将两种或多种流体混合，例如将血液溶液与浸入缓冲液中的生物标记物混合。因此，微型混合器是LOC的重要组成部分。由于微混合器在化学反应，分散体和乳化中的应用范围非常广泛，因此使混合器具有出色的混合效率非常重要。在微流体装置中难以实现充分混合的原因是层流，这可以用低雷诺数来解释。有时它的值小于^1。2,3流动是层流的，没有湍流，这使分子扩散成为混合的主要机理。仅通过扩散就不能实现高混合效率。在通过扩散混合的过程中，低分子量分子的混合持续时间较短，而核酸等高分子量分子不仅需要更长的微通道长度，还需要更长的持续时间（数分钟至数小时）以确保完全混合。⁴因此，在这些设备中以低雷诺数进行流体混合是一个挑战，因为流体流动的通道或腔室非常短，并且发生混合过程的时间受控。可以通过修改设计结构或施加一些外力来增强混合性能。⁵