Axial gradients in wall elasticity may have significant implications in the deformation and flow characteristics of a narrow fluidic conduit, bearing far-reaching consequences in physiology and bio-engineering. Here, we present a theoretical and experimental framework for fluid–structure interactions in microfluidic channels with axial gradients in wall elasticity, in an effort to arrive at a potential conceptual foundation for in vitro study of mirovascular physiology. Towards this, we bring out the static deformation and steady flow characteristics of a circular microchannel made of polydimethylsiloxane (PDMS) bulk, considering imposed gradients in the substrate elasticity. In particular, we study two kinds of elasticity variations – a uniformly soft (or hard) channel with a central strip that is hard (or soft), and, increasing elasticity along the length of the channel. The former kind yields a centrally constricted (or expanded) deformed profile in response to the flow. The latter kind leads to increasingly bulged channel radius from inlet to outlet in response to flow. We also formulate an analytical model capturing the essential physics of the underlying elastohydrodynamic interactions. The theoretical predictions match favourably with the experimental observations and are also in line with reported results on stenosis in mice. The present framework, thus, holds the potential for acting as a fundamental design basis towards developing in vitro models for micro-circulation, capable of capturing exclusive artefacts of healthy and diseased conditions.

中文翻译：

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具有壁弹性轴向梯度的柔性微流体通道的流动和变形特性。

壁弹性的轴向梯度可能会对狭窄的流体导管的变形和流动特性产生重大影响，从而对生理学和生物工程学产生深远的影响。在这里，我们提出了具有壁弹性轴向梯度的微流体通道中流体-结构相互作用的理论和实验框架，以期为体外获得潜在的概念基础微血管生理学的研究。为此，考虑到基材弹性的梯度，我们得出了由聚二甲基硅氧烷（PDMS）制成的圆形微通道的静态变形和稳态流动特性。特别是，我们研究了两种弹性变化–均匀柔软（或硬）的通道，中央带较硬（或柔软），以及沿着通道长度增加的弹性。前一种响应于流动产生中心收缩（或膨胀）的变形轮廓。后者导致响应于流量从入口到出口的凸出的通道半径越来越大。我们还制定了一个分析模型，以捕获基本的弹性流体动力相互作用的基本物理原理。理论上的预测与实验结果吻合良好，也与关于小鼠狭窄的报道结果相吻合。因此，本框架具有作为开发的基本设计基础的潜力。用于微循环的体外模型，能够捕获健康和患病状况的专有伪像。