Department of Mechanical and Industrial Engineering, University of Illinois at Chicago , Chicago, Illinois 60607, United States.
ACS Appl Mater Interfaces. 2014 Aug 13;6(15):12837-43. doi: 10.1021/am5028204. Epub 2014 Jul 14.
Many important applications in fluid management could benefit from unidirectional transport through porous media via a simple, large-area, low-cost coating treatment; in essence, a fluid diode demonstrated herein for water using common cellulosic paper substrates. In electronics, the diode is an electrical component with asymmetric current transfer characteristics. A light (<2 g/m(2)) superhydrophobic conformal coating applied onto one side of a porous substrate is shown to create a liquid transport function analogous to the electronic diode, facilitating fluid movement in one direction under negligible penetration pressures, but opposing it in reverse up to greater pressures. The phenomenon is driven by capillary action and can be observed using any similarly-thin fluid barrier applied on only one side (i.e., wettability contrast) of an absorbent porous matrix. Diodic action and liquid transport rates are shown to be highly tunable, determined by fiber diameter and spacing, in combination with coating deposition amount. As an example, the device is used to separate an oil/water mixture, relying upon the surface tension differences of the mixture constituents, and may be implemented in multicomponent fluid filtration/separation technologies.
许多重要的流体管理应用都可以受益于通过简单、大面积、低成本的涂层处理在多孔介质中进行单向传输；实质上，本文展示了一种使用常见纤维素纸基的水用流体二极管。在电子学中，二极管是一种具有不对称电流传输特性的电子元件。在多孔基底的一侧施加一层轻（<2 g/m(2)）的超疏水共形涂层，就可以创建类似于电子二极管的液体传输功能，在可忽略的渗透压力下促进流体单向流动，但在反向时会遇到更大的阻力。这种现象是由毛吸作用驱动的，可以使用任何类似的薄流体屏障在仅一侧（即润湿性对比）的多孔吸收基质上观察到。二极管效应和液体传输速率具有高度可调节性，取决于纤维直径和间距以及涂层沉积量。例如，该装置用于分离油/水混合物，依靠混合物成分的表面张力差异，并且可以在多组分流体过滤/分离技术中实现。
