Holographic microscopy and microfluidics platform for measuring wall stress and 3D flow over surfaces textured by micro-pillars.
Holographic microscopy and microfluidics platform for measuring wall stress and 3D flow over surfaces textured by micro-pillars.
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DOI：
10.1038/srep28753
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发表时间：
2016-06-29
影响因子：
4.6
通讯作者：
Sheng J
中科院分区：
文献类型：
--
作者：
Bocanegra Evans H;Gorumlu S;Aksak B;Castillo L;Sheng J
了解流体流动如何与微纹理表面相互作用对于广泛的关键生物过程和工程应用至关重要，包括颗粒分散、病原体感染和通过表面拓扑进行的阻力操纵。我们使用高速数字全息显微镜（DHM）结合基于相关性的去噪算法，以克服由表面粗糙度产生的光学干扰，并捕获大量的微流通道中的3D粒子轨迹与微柱图案化的一个表面。它使我们能够获得三维速度场的不确定度为0.06%和二维壁面剪应力分布的分辨率为~65 μPa。与大多数微流体中的层流相反，我们发现纹理微通道的流动是三维且复杂的。虽然微柱局部影响速度流场，但它们的存在在通道壁处的壁剪切应力方面是全局性的。这些发现意味着，微尺度混合和壁应力传感/操纵可以通过流体动力学平滑，但拓扑粗糙的微柱实现。
Understanding how fluid flow interacts with micro-textured surfaces is crucial for a broad range of key biological processes and engineering applications including particle dispersion, pathogenic infections, and drag manipulation by surface topology. We use high-speed digital holographic microscopy (DHM) in combination with a correlation based de-noising algorithm to overcome the optical interference generated by surface roughness and to capture a large number of 3D particle trajectories in a microfluidic channel with one surface patterned with micropillars. It allows us to obtain a 3D ensembled velocity field with an uncertainty of 0.06% and 2D wall shear stress distribution at the resolution of ~65 μPa. Contrary to laminar flow in most microfluidics, we find that the flow is three-dimensional and complex for the textured microchannel. While the micropillars affect the velocity flow field locally, their presence is felt globally in terms of wall shear stresses at the channel walls. These findings imply that micro-scale mixing and wall stress sensing/manipulation can be achieved through hydro-dynamically smooth but topologically rough micropillars.