Multibioinspired JANUS Membranes with Spatial Surface Refreshment for Enhanced Fog Collection

Abstract

To meet the requirement of efficient surface refreshment and rapid droplet transport for high-efficiency fog collection, a Janus membrane with complementary hydrophobic/hydrophilic wetting on the opposite surface was further developed, exhibiting promising potential for efficient fog collection. [19][20][21][22] However, how to increase the permeability of the holes to enable an efficient transport of water from the droplet condensation side to the water collection side is still limited. [21][22][23] In this research, inspired by the synergistic effects of hybrid wettability of Namib desert beetles, curvature gradient of Shorebird's beaks and capillary wicking effect of tree roots, we design a multibioinspired Janus membrane (MJM), which is composed of a hydrophobic upper surface, superhydrophilic conical micropores and porous sponge for enhanced fog collection. The MJM can generate not only a surface refreshment in the horizontal direction due to hybrid wettability, but also a vertical one enabled by curvature gradient and capillary wicking. The strategy with combined spatial surface refreshment on the MJM endows a higher water collection efficiency, in contrast to conventional Janus membranes where filled micropores hinder surface refreshment in horizontal and vertical direction. We further demonstrated that the MJM possesses a high weather resistance due to its robust Janus state in air.

Bionic Surfaces for Fog Collection: A Comprehensive Review of Natural Organisms and Bioinspired Strategies

“…An advanced Janus membrane with a hydrophobic surface, superhydrophilic cone micropores, and a multiporous sponge, is 125% more efficient compared to conventional Janus membranes. 133 The closing motion of the shorebird's beak is imitated using a 3D printing process, employing PDMS and a temperatureresponsive gel, Poly(N-isopropylacrylamide) (PNIPAAm). 134 SWCA rises from 63.5°± 1.6°to 93.2°± 2.2°on a flat surface decorated by PNIPAAm, as the temperature rises from 20.0 to 40.0 °C.…”

Surface and Interface Engineering of Polymer Membranes: Where We Are and Where to Go

“…For example, Lv et al protected one side of the cellulose membrane by an adhesive tape from the hydrophobic modification . Liu et al adhered the polyimide tape with hydrophobic siloxane on the metal membrane for one-side modification . Wang et al modified the PTFE membrane with PDA and then removed the top modification layer by tape .…”

Biomimetic directional transport for sustainable liquid usage

“…Janus membranes were the material with different properties or components on two faces [31], and were widely spread since 1991 [32]. To enhance the membrane's fog collection efficiency, Liu et al proposed a multibioinspired Janus membrane (MJM) with conical micropores and porous sponges by mimicking the shorebird's beak shape and others (Figure 5a) [33]. The novel membrane was composed of a hydrophobic upper surface, superhydrophilic conical micropores, and porous sponge and showed greater efficiency, increasing 125% compared with the traditional Janus membrane.…”

“… (a) Side view of the multibioinspired Janus membrane (MJM) [33]. (b) Composition of the superhydrophilic‐hydrophobic integrated conical stainless steel needle [45].…”