Panter Jack R, Gizaw Yonas, Kusumaatmaja Halim
Department of Physics, Durham University, South Road, Durham DH1 3LE, U.K.
The Procter and Gamble Co., Mason Business Center, 8700 S. Mason-Montgomery Road, Mason, Ohio 45040, United States.
Langmuir. 2020 Jul 7;36(26):7463-7473. doi: 10.1021/acs.langmuir.0c01039. Epub 2020 Jun 16.
Joint physically and chemically pattered surfaces can provide efficient and passive manipulation of fluid flow. The ability of many of these surfaces to allow only unidirectional flow means they are often termed fluid diodes. Synthetic analogues of these are enabling technologies from sustainable water collection via fog harvesting to improved wound dressings. One key fluid diode geometry features a pore sandwiched between two absorbent substrates-an important design for applications that require liquid capture while preventing back-flow. However, the enclosed pore is particularly challenging to design as an effective fluid diode due to the need for both a low Laplace pressure for liquid entering the pore and a high Laplace pressure to liquid leaving. Here, we calculate the Laplace pressure for fluid traveling in both directions on a range of conical pore designs with a chemical gradient. We show that this chemical gradient is in general required to achieve the largest critical pressure differences between incoming and outgoing liquids. Finally, we discuss the optimization strategy to maximize this critical pressure asymmetry.
物理和化学图案化的联合表面能够实现对流体流动的高效被动操控。许多这类表面仅允许单向流动的特性意味着它们常被称为流体二极管。其合成类似物推动了从通过雾收集实现可持续集水到改进伤口敷料等技术的发展。一种关键的流体二极管几何结构的特征是一个夹在两个吸收性基底之间的孔隙——这是一种对于需要液体捕获同时防止回流的应用而言很重要的设计。然而，由于既要使液体进入孔隙时的拉普拉斯压力低，又要使液体离开时的拉普拉斯压力高，设计一个有效的流体二极管时，封闭孔隙极具挑战性。在此，我们计算了在一系列具有化学梯度的锥形孔隙设计上流体双向流动时的拉普拉斯压力。我们表明，一般而言，需要这种化学梯度才能在流入和流出液体之间实现最大的临界压力差。最后，我们讨论了使这种临界压力不对称性最大化的优化策略。
