Khattak Hamza K, Karpitschka Stefan, Snoeijer Jacco H, Dalnoki-Veress Kari
Department of Physics and Astronomy, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4M1, Canada.
Max Planck Institute for Dynamics and Self-Organization, 37077, Göttingen, Germany.
Nat Commun. 2022 Jul 30;13(1):4436. doi: 10.1038/s41467-022-31910-3.
When a droplet is placed on a soft surface, surface tension deforms the substrate, creating a capillary ridge. We study how the motion of the ridge dissipates energy in microscopic droplets. Using a micropipette based method, we are able to simultaneously image and measure forces on a microscopic droplet moving at a constant speed along a soft film supported on a rigid substrate. Changing the thickness of the thin film tunes the effective stiffness of the substrate. Thus we can control the ridge size without altering the surface chemistry. We find that the dissipation depends strongly on the film thickness, decreasing monotonically as effective stiffness increases. This monotonic trend is beyond the realm of small deformation theory, but can be explained with a simple scaling analysis.
当一滴液体放置在柔软表面上时，表面张力会使基底变形，形成一个毛细脊。我们研究了毛细脊的运动如何在微观液滴中耗散能量。使用基于微量移液器的方法，我们能够同时对沿着刚性基底上支撑的软膜以恒定速度移动的微观液滴进行成像并测量其受力情况。改变薄膜的厚度可调节基底的有效刚度。因此，我们可以在不改变表面化学性质的情况下控制毛细脊的尺寸。我们发现，耗散强烈依赖于薄膜厚度，随着有效刚度的增加单调递减。这种单调趋势超出了小变形理论的范畴，但可以通过简单的标度分析来解释。
