Ranchon Hubert, Cacheux Jean, Reig Benjamin, Liot Olivier, Teerapanich Pattamon, Leichlé Thierry, Joseph Pierre, Bancaud Aurélien
LAAS-CNRS, Université de Toulouse, CNRS , 31031 Toulouse, France.
Langmuir. 2018 Jan 30;34(4):1394-1399. doi: 10.1021/acs.langmuir.7b03962. Epub 2018 Jan 17.
We investigate the pressure-driven transport of particles 200 or 300 nm in diameter in shallow microfluidic channels ∼1 μm in height with a bottom wall characterized by a high roughness amplitude of ∼100 nm. This study starts with the description of an assay to generate cracks in hydrophilic thin polymer films together with a structural characterization of these corrugations. Microfluidic chips of variable height are then assembled on top of these rough surfaces, and the transport of particles is assessed by measuring the velocity distribution function for a set of pressure drops. We specifically detect anomalous transport properties for rough surfaces. The maximum particle velocity at the centerline of the channel is comparable to that obtained with smooth surfaces, but the average particle velocity increases nonlinearly with the flow rate. We suggest that the change in the boundary condition at the rough wall is not sufficient to account for our data and that the occurrence of contacts between the particle and the surface transports the particle away from the wall and speeds up its motion. We finally draw perspectives for the separation by field-flow fractionation.
我们研究了直径为200或300纳米的颗粒在高度约为1微米的浅微流体通道中的压力驱动输运，该通道的底壁具有约100纳米的高粗糙度幅度。本研究首先描述了一种在亲水性聚合物薄膜中产生裂纹的实验方法以及这些波纹的结构特征。然后将不同高度的微流体芯片组装在这些粗糙表面上，并通过测量一组压力降下的速度分布函数来评估颗粒的输运。我们特别检测到粗糙表面的异常输运特性。通道中心线处的最大颗粒速度与光滑表面的相当，但平均颗粒速度随流速非线性增加。我们认为粗糙壁处边界条件的变化不足以解释我们的数据，并且颗粒与表面之间接触的发生将颗粒从壁上运走并加速其运动。我们最后展望了场流分级分离的前景。
