In this paper, we present a microfluidic filter to improve mixing index and eliminate the pulsatile component within microfluidic devices, which is similar to a second-order RC low-pass filter in electronics. COMSOL Multiphysics, a kind of simulation software, is used to evaluate the analytical method and the efficiency of the device. Compared with the results obtained from the equivalent circuit theory, the simulation method has been verified. In addition, the equivalent circuit theory, in other words the fluid dynamical equivalent of Ohm’s law, is adopted to make the theoretical analysis. This microfluidic filter is equipped with multiple simple channels and microcavities having elastic membrane at the top layer, just like the series–parallel connection of resistors and capacitors. Based on the results, one microcavity is equivalent to first-order filter and two microcavities in series equal second-order filter which shows the better filtering effect. Actually, when the driving frequency exceeds 60 Hz, this device can export almost steady fluid. The mixing effect is improved compared with the simple microfluidic junctions. The combined application of microfluidics and equivalent circuit theory will gain insightful ideas and practical design methods for developing unique microfluidic devices to address a broad range of biological and chemical challenges.

中文翻译：

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二阶微流过滤器的数值模拟

在本文中，我们提出了一种微流体滤波器，以改善混合指数并消除微流体设备中的脉动成分，这类似于电子产品中的二阶RC低通滤波器。COMSOL Multiphysics是一种仿真软件，用于评估分析方法和设备效率。与等效电路理论的结果相比较，仿真方法得到了验证。另外，采用等效电路理论，即欧姆定律的流体动力学等效原理进行理论分析。这种微流体过滤器配备有多个简单的通道和微腔，这些腔和微腔在顶层具有弹性膜，就像电阻器和电容器的串联-并联连接一样。根据结果​​，一个微腔等效于一阶滤波器，两个微腔串联等效的二阶滤波器，显示出更好的滤波效果。实际上，当驱动频率超过60 Hz时，此设备可以输出几乎稳定的流体。与简单的微流体连接相比，混合效果得到改善。微流体学和等效电路理论的结合应用将获得深入的思想和实用的设计方法，以开发独特的微流体设备来应对广泛的生物学和化学挑战。