Highly Efficient Multiscale Fog Collector Inspired by Sarracenia Trichome Hierarchical Structure

Abstract

normally tend to condense on the protruding solid surface, but the already condensed bulked water film will slow down further condensation. [6][7][8] In nature, many biological samples have developed unique parts to solve the bulked water film-restrained fog condensation, [9][10][11] such as spider silk with spindle-knots [12][13][14] and cactus with cone spines. [15][16][17] Their conical structures can directionally transport condensed water from the tip to the bottom, releasing the tip surface area for further fog condensation. [18][19][20][21][22] Conical structures are usually combined with fog harps to construct fog collectors for highly efficient fog harvesting. [23][24][25][26][27][28] However, the velocity of directional water transport on these conical structures remains of ≈0.5 mm s −1 , which limits further enhancement of fog harvesting by fog collectors.Fortunately, a more efficient fog harvesting and transport mode was discovered on Sarracenia trichomes that has a unique hierarchical microchannel structure around the needle-shaped trichomes (Figure 1a). [29] A thin water film is automatically formed on the hierarchical microchannel structure to generate superslippery capillaries, which remarkably enhances the water transport capability and further reinforces the fog harvesting efficiency of trichomes. The hierarchical microchannel shows greater properties than the uniform microchannel, which can also aid on the development of new microfluidic systems. [30][31][32][33] However, the underlying dynamic mechanism of hierarchical microchannel-induced ultrafast transport on fog harvesting is still ambiguous, and the multiscale structural coupling effect on fog harvesting performance is also a great challenge.Herein, we propose an effective strategy to fabricate a bionic Sarracenia trichome (BST) using a one-step thermoplastic stretching approach on a glass fiber bundle under the constraint of an inner gear pattern. The BST possesses an ondemand hierarchical microchannel structure, whose major channels are confined by an inner gear pattern, as well as junior microchannels are automatically assembled by the glass fiber monofilaments. Its excellent gravity-ignoring fog harvesting property was herein demonstrated, which was governed by a superslippery sliding mode, similar to the real Sarracenia trichome. The capillary condensation and fog harvesting theoretical model of BST was built to further discuss the dynamic Fog harvesting through bionic strategies to solve water shortage has drawn considerable attention. Recently, an ultrafast fog harvesting and transport mode was identified in Sarracenia trichome, which is mainly attributed to its superslippery capillary force induced by its unique hierarchical microchannel. However, the underlying effect of hierarchical microchannel-induced ultrafast transport on fog harvesting and the multiscale structural coupling effect on highly efficient fog harvesting are still great challenges. Herein, a bionic Sarracenia trichome (BST) with an on-demand regular hierarchical ...

Anisotropic Hemiwicking Behavior on Laser Structured Prismatic Microgrooves

“…For rough solid surfaces, the deposited liquid droplets exhibit three kinds of classic wetting models: the Wenzel state, Cassie–Baxter state, and hemiwicking state, which are determined by the surface structure and interfacial interactions of liquids and solids. − In the hemiwicking state, the fluid spontaneously imbibes or wicks along the narrow micro-/nanostructured roughness ahead of the fluid droplet under the balance of the capillary force and the viscous force, like wicking behaviors. In recent years, the wicking phenomenon, including wicking and hemiwicking, has attracted increasing attention for its significance in engineering applications, such as thermal management, − water harvesting, − fuel cells, microfluidics, − and biosciences, in which the wicking behavior determined by micro-/nanostructures plays a critical role in the process of liquid transportation. The mechanism of the wicking process is rather complex, mainly involved in the competition of the drive of the capillary force and the hindering of the viscous force, both of which favor smaller length scales.…”

High-Efficient Fog Harvest from a Synergistic Effect of Coupling Hierarchical Structures

“…The ultrafast liquid transport has been found on the Sarracenia trichome, and its unique HMC with high–low ribs has also been proved to play a great role in fog capture and harvesting. , In order to reveal the influence of different HMCs, the needles with N high ribs and n low ribs are set under the same saturated fog flow of 0.35 m/s. Fluorescent particles were doped in saturated fog and activated by ultraviolet light to better observe the fog harvest process.…”

Bioinspired superwetting materials for water manipulation

“…The artificial trichome can harvest fog ultrafast and transfer water against gravity like the genuine Sarracenia trichome. 108 Wang et al 106 reported a subulate Cu sheet with Sarracenia-like multilevel microchannels and cactus spines developed by pulsed laser direct structuring for continuous and high-performance water collection (Figure 9f). This unique combined structure (a spine with barbs and hierarchical channels) presented the highest fog harvesting speed (513 μg s −1 ) compared to the hierarchical channels (315 μg s −1 ), the spine with barbs and grooves (340 μg s −1 ), and the spine with barbs (377 μg s −1 ).…”

“…The major channels were constructed by an inner gear pattern, while the junior microchannels were automatically generated because of the assembly of glass fiber monofilaments. The artificial trichome can harvest fog ultrafast and transfer water against gravity like the genuine Sarracenia trichome 108 . Wang et al 106 reported a subulate Cu sheet with Sarracenia ‐like multilevel microchannels and cactus spines developed by pulsed laser direct structuring for continuous and high‐performance water collection (Figure 9f).…”