Department of Bioengineering, University of California, 420 Westwood Plaza, 5121 Engineering V, PO Box 951600, Los Angeles, California 90095, USA.
Nat Commun. 2013;4:1826. doi: 10.1038/ncomms2841.
Controlling the shape of fluid streams is important across scales: from industrial processing to control of biomolecular interactions. Previous approaches to control fluid streams have focused mainly on creating chaotic flows to enhance mixing. Here we develop an approach to apply order using sequences of fluid transformations rather than enhancing chaos. We investigate the inertial flow deformations around a library of single cylindrical pillars within a microfluidic channel and assemble these net fluid transformations to engineer fluid streams. As these transformations provide a deterministic mapping of fluid elements from upstream to downstream of a pillar, we can sequentially arrange pillars to apply the associated nested maps and, therefore, create complex fluid structures without additional numerical simulation. To show the range of capabilities, we present sequences that sculpt the cross-sectional shape of a stream into complex geometries, move and split a fluid stream, perform solution exchange and achieve particle separation. A general strategy to engineer fluid streams into a broad class of defined configurations in which the complexity of the nonlinear equations of fluid motion are abstracted from the user is a first step to programming streams of any desired shape, which would be useful for biological, chemical and materials automation.
从工业加工到控制生物分子相互作用。以前控制流体流的方法主要集中在创建混沌流以增强混合。在这里，我们开发了一种使用流体变换序列而不是增强混沌来施加秩序的方法。我们研究了在微流道内的单个圆柱形支柱库周围的惯性流变形，并组装这些净流体变换来设计流体流。由于这些变换提供了从支柱上游到下游的流体单元的确定性映射，因此我们可以顺序排列支柱以应用相关的嵌套映射，从而在无需额外数值模拟的情况下创建复杂的流体结构。为了展示各种能力，我们展示了将流的横截面形状雕刻成复杂几何形状、移动和分裂流体流、进行溶液交换和实现颗粒分离的序列。将流体流设计成广泛定义的配置类的通用策略，其中流体运动的非线性方程的复杂性从用户抽象出来，这是将任何所需形状的流编程的第一步，这对于生物、化学和材料自动化将非常有用。
