Multi-Bioinspired Janus Copper Mesh for Improved Gravity-Irrelevant Directional Water Droplet and Flow Transport

Abstract

A conceptually novel multi-bioinspired strategy based on structures and functions derived from the Namib desert beetle and lotus leaf is proposed in this paper. The proposed scheme synergistically combines the features of alternating wettability patterns and asymmetric wettability for improved directional water transport. Consequently, a Janus copper mesh, which substantially outperforms other single-bioinspired synthetic materials, is produced. The Janus copper mesh achieves directional self-transportation of tiny water droplets and continuous water flow in a gravity-irrelevant or an anti-gravity manner without energy consumption. This depends on the asymmetric wettability and alternating hydrophobic-hydrophilic wettability patterns on the hydrophobic surface of the mesh. In particular, Janus copper shows remarkable selective directional water transport in a water−oil system, rendering it a promising candidate for practical applications.

Bioinspired Under-Liquid Dual Superlyophobic Surface for On-Demand Oil/Water Separation

“…Following this principle, a copper substrate with alternating wettability (similar to that of desert beetle backs) and under-liquid dual superlyophobic characteristics was successfully prepared by a simple liquidus modification method (Figure a). First, a copper sheet was oxidized in a mixed alkaline solution to generate a Cu­(OH) 2 nanowire-covered surface with superhydrophilic/underwater superoleophobic properties. − The oxidized copper mesh was vertically dipped into an NDM/ethanol solution with a relatively low concentration of 1 mM for different times to attain special wettability by generating superhydrophobic nanodomains isolated from the superhydrophilic surface. The under-liquid wetting behaviors (under-oil water CA denoted as OW and under-water oil CA denoted as WO) of the copper substrates prepared at different modification times were examined in different oil/water systems (Figure b).…”

Substrate-Independent Cupric Phosphate Nanoflower–Mineralized Superhydrophilic Membranes for Diverse Oil–Water Separation

“…The increased release of oily wastewater from industries and frequent oil spillage accidents in oceans have resulted in severe pollution, ecological imbalance, and substantial economic damages. – Separating oil from oily wastewater is an important and worldwide challenge that needs to be urgently addressed. Membrane separation technology has garnered considerable attention for the treatment of diverse oily wastewater because of its low power consumption and high efficiency. – However, membrane fouling is a considerable disadvantage of traditional membranes because it sharply decreases the membrane flux due to oil adhesion-induced pore clogging.…”

Effect of Droplet-Laden Fibers on Aerodynamics of Fog Collection on Vertical Fiber Arrays

“…Often inspired by nature, such approaches are termed biomimetic surface design. They include desert beetle-inspired surfaces with heterogeneous wettability, , Janus membranes with front-to-back wettability gradient for fast water removal, − utilizing Laplace pressure gradient caused by asymmetric curvatures on conical surfaces, , or incorporating special topological features which enable unidirectional motions of droplets. − Shi et al developed fog harps, which are arrays of vertical fibers and give enhanced fog-harvesting performance due to the absence of cross fibers, which otherwise hinder droplet motion leading to pinning of droplets and clogging of mesh pores. As pointed out in a recent review by Jiang et al, fog harvesting is distinct from dew harvesting.…”