Cottin-Bizonne Cécile, Barrat Jean-Louis, Bocquet Lydéric, Charlaix Elisabeth
Laboratoire de Physique de la Matière Condensée et Nanostructures, CNRS and Université de Lyon, Bâtiment Léon Brillouin, 43 Boulevard du 11 Novembre, 69622 Villeurbanne Cedex, France.
Nat Mater. 2003 Apr;2(4):237-40. doi: 10.1038/nmat857.
With the important development of microfluidic systems, miniaturization of flow devices has become a real challenge. Microchannels, however, are characterized by a large surface-to-volume ratio, so that surface properties strongly affect flow resistance in submicrometre devices. We present here results showing that the concerted effect of wetting properties and surface roughness may considerably reduce friction of the fluid past the boundaries. The slippage of the fluid at the channel boundaries is shown to be greatly increased by using surfaces that are patterned on the nanometre scale. This effect occurs in the regime where the surface pattern is partially dewetted, in the spirit of the 'superhydrophobic' effects that have been discovered at macroscopic scales. Our results show for the first time that, in contrast to common belief, surface friction may be reduced by surface roughness. They also open the possibility of a controlled realization of the 'nanobubbles' that have long been suspected to play a role in interfacial slippage.
随着微流控系统的重要发展，流动装置的小型化已成为一项真正的挑战。然而，微通道的特点是表面积与体积之比很大，因此表面性质会强烈影响亚微米级装置中的流动阻力。我们在此展示的结果表明，润湿性和表面粗糙度的协同作用可能会显著降低流体经过边界时的摩擦力。通过使用纳米级图案化的表面，流体在通道边界处的滑移被证明会大大增加。这种效应发生在表面图案部分去湿的状态下，类似于在宏观尺度上发现的“超疏水”效应。我们的结果首次表明，与普遍看法相反，表面粗糙度可能会降低表面摩擦力。它们还开启了可控实现长期以来被怀疑在界面滑移中起作用的“纳米气泡”的可能性。
