University of Illinois at Urbana-Champaign , 1206 W. Green Street, Urbana, Illinois 61801, United States.
ACS Appl Mater Interfaces. 2017 Sep 27;9(38):33333-33340. doi: 10.1021/acsami.7b11143. Epub 2017 Sep 13.
Although many recent studies demonstrate surfaces with switchable wettability under various external stimuli, a deliberate effort to self-propel liquid droplets utilizing a surface wetting mode switch between slippery lotus and adhesive rose petal states via a mechanical strain has not been made yet, which would otherwise further benefit microfluidic applications. In this work, we present a black silicon/elastomer (bSi/elastomer) composite surface which shows switchable wettability and adhesion across the two wetting modes by mechanical stretching. The composite surface is composed of a scale-like nanostructured silicon platelet array that covers an elastomer surface. The gap between the neighboring silicon platelets is reversibly changeable as a function of a mechanical strain, leading to the transition between the two wetting modes. Moreover, the composite surface is highly flexible although its wetting properties primarily originate from superhydrophobic bSi platelets. Different wetting characteristics of the composite surface in various mechanical strains are studied, and droplet manipulation such as droplet self-propulsion and pick-and-place using the composite surface is demonstrated, which highlights its potentials for microfluidic applications.
尽管许多最近的研究表明，在各种外部刺激下，表面具有可切换的润湿性，但尚未通过机械应变利用表面润湿性模式在光滑荷叶和粘性玫瑰花瓣状态之间进行自推进液滴的有意努力，否则这将进一步有益于微流控应用。在这项工作中，我们提出了一种黑硅/弹性体（bSi/elastomer）复合材料表面，该表面通过机械拉伸在两种润湿模式之间表现出可切换的润湿性和粘附性。该复合表面由覆盖在弹性体表面上的鳞片状纳米结构硅片阵列组成。相邻硅片之间的间隙可以作为机械应变的函数而可逆地变化，从而导致两种润湿模式之间的转变。此外，尽管其润湿性主要源自超疏水 bSi 薄片，但复合表面具有很高的柔韧性。研究了复合表面在不同机械应变下的不同润湿特性，并演示了使用复合表面进行的液滴自推进和拾取放置等操作，突出了其在微流控应用中的潜力。
