A bio-inspired flexible fiber array with an open radial geometry for highly efficient liquid transfer

Abstract

Generally, highly efficient liquid transfer is difficult to achieve in open fibrous systems, as compared with traditional closed systems, because capillary coalescence frequently occurs when fiber arrays interact with a liquid. Dandelion pappi, which are flexible fiber arrays with open radial geometries, exhibit the unique ability to capture and hold large amounts of water steadily. Drawing inspirations from this natural system, we developed an artificial flexible glass fiber array with a radial geometry that is capable of holding large volumes of liquid and controllably transferring the liquid onto a substrate. The highly efficient liquid transfer of the open fibrous array can be attributed to the synergistic effects of the flexibility of fibers that radially arranged with a big open angle that enables a distinct elastic deformation of the fibers and the consequent formation of a large space within the fiber array for liquid storage, and the highly adhesive property of fibers that helps the pining of three-phase contact line on the fibers. This unique open system may provide a novel strategy for highly efficient and controllable liquid transfer.

Bioinspired Dynamic Wetting on Multiple Fibers

“…Dandelion pappi can encapsulate large droplets after rain, which is one strategy for using environmental water (Figure 5a 1 ). [15] As shown in Figure 5a 2 , when drawn out of the water surface, the deformed pappi can encapsulate a large water droplet. The captured droplet can weigh up to 96 times more than the pappi, which demonstrates the highly efficient liquid capture ability of the pappi.…”

“…a,b) Reproduced with permission. [15] Copyright 2014, Nature Publishing Group. c) Reproduced with permission.…”

“…[2] The cactus spine was recently reported to be capable of collecting and directionally transporting droplets, [3] and spider silk can efficiently harvest water from humid air. [4] The distinctive conical structure of the individual natural fiber www.advmat.de www.advancedsciencenews.com on water strider legs, [12] directional liquid transport inspired by the shorebird beak, [13] controllable liquid transfer inspired by the Chinese brush, [14] highly efficient liquid encapsulation inspired by dandelion pappi, [15] and capillary-induced fiber self-assembly inspired by wet hairs. [16] We focus on multiple fibrous systems with different spatial distributions, which are more complicated and challenging but offer more possibilities for practical applications.…”

Bio-inspired flexible fiber brushes that keep liquids in a controlled manner by closing their ends

“…[1][2][3][4] In many cases, these devices are dipped in liquid baths and are then removed to keep liquids in the devices, just like Chinese calligraphic brushes, which are traditional writing and painting tools in East Asia. The fibers of Chinese brushes are cylindrical, except for their conical ends.…”

“…Flexible fibers and plates at interfaces show elastic deformations owing to hydrostatic pressures and capillary forces. 3,4,[7][8][9][10][11][12] With sufficiently large hydrostatic pressures and/or capillary forces, the outmost fibers of a Chinese brush (which are at the interface between the ambient and the water) are bent toward the interior of the brush until the ends of these fibers touch at the end of the brush. Because the space between the fibers vanishes at the closed ends of brushes, closing the ends of brushes may eliminate the remnant droplets.…”