Soroori Salar, Kulinsky Lawrence, Kido Horacio, Madou Marc
Department of Biomedical Engineering, University of California, Irvine, CA, 92697, USA.
Department of Mechanical & Aerospace Engineering, University of California, Irvine, CA, 92697, USA.
Microfluid Nanofluidics. 2014 Jun;16(6):1117-1129. doi: 10.1007/s10404-013-1277-7.
Microfluidic discs have been employed in a variety of applications for chemical analyses and biological diagnostics. These platforms offer a sophisticated fluidic toolbox, necessary to perform processes that involve sample preparation, purification, analysis, and detection. However, one of the weaknesses of such systems is the uni-directional movement of fluid from the disc center to its periphery due to the uni-directionality of the propelling centrifugal force. Here we demonstrate a mechanism for fluid movement from the periphery of a hydrophobic disc toward its center that does not rely on the energy supplied by any peripheral equipment. This method utilizes a ventless fluidic network that connects a column of working fluid to a sample fluid. As the working fluid is pushed by the centrifugal force to move toward the periphery of the disc, the sample fluid is pulled up toward the center of the disc analogous to a physical pulley where two weights are connected by a rope passed through a block. The ventless network is analogous to the rope in the pulley. As the working fluid descends, it creates a negative pressure that pulls the sample fluid up. The sample and working fluids do not come into direct contact and it allows the freedom to select a working fluid with physical properties markedly different from those of the sample. This article provides a demonstration of the "micro-pulley" on a disc, discusses underlying physical phenomena, provides design guidelines for fabrication of micro-pulleys on discs, and outlines a vision for future micro-pulley applications.
微流控盘已被应用于各种化学分析和生物诊断领域。这些平台提供了一个复杂的流体工具箱，这是执行涉及样品制备、纯化、分析和检测等过程所必需的。然而，此类系统的一个弱点是，由于推进离心力的单向性，流体从盘中心向其周边单向移动。在此，我们展示了一种流体从疏水盘周边向其中心移动的机制，该机制不依赖于任何外围设备提供的能量。此方法利用了一个无通风口的流体网络，该网络将一列工作流体与样品流体相连。当工作流体在离心力作用下被推向盘的周边时，样品流体被向上拉向盘的中心，类似于一个物理滑轮，其中两个重物通过一根穿过滑轮的绳子相连。无通风口网络类似于滑轮中的绳子。当工作流体下降时，它会产生一个负压，将样品流体向上拉。样品流体和工作流体不会直接接触，这使得可以自由选择一种物理性质与样品明显不同的工作流体。本文展示了盘上的“微滑轮”，讨论了潜在的物理现象，提供了盘上微滑轮制造的设计指南，并概述了未来微滑轮应用的愿景。
