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With the variety of fibers and fabrics, the studies of the surface structure of the textile yarns, the weave fabric, and their surface wettability are still potential factors to improve and optimize the fog harvesting efficiency. In this work, inspired by the fog harvesting behavior of the desert beetle dorsal surface, a wavy–bumpy structure of post-weave yarn (obtained from woven fabric) was reported to improve large droplet growth (converge) efficiency. In which, this study used tetrabutyl titanate (Ti(OC4H9)4) to waterproof, increase hydrophobicity, and stabilize the surface of yarns and fabric (inspired by the feather structure and lotus leaf surface). Moreover, PDMS oil was used (lubricated) to increase hydrophobicity and droplet shedding on the yarns (inspired by the slippery surface of the pitcher plant) and at the same time, enhance the fog harvesting efficiency of the warp yarn woven fabric (Warp@fabric). In addition, a three-dimensional adjacent yarn structure was arranged by two non-parallel fabric layers. The yarns of the inner and outer layers were intersected at an angle decreasing to zero (mimicking the water transport behavior of Shorebird's beaks). This method helped large droplets quickly form and shed down easily. More than expected, the changes in fabric texture and fiber surface yielded an excellent result. The OBLWB-Warp@fabric's water harvesting rate was about 700% higher than that of the original plain weave fabric (Original@fabric). OBLWB-Warp@fabric's water harvesting rate was about 160% higher than that of Original–Warp@fabric. This shows the great practical application potential of woven fabrics with a low cost and large scale, or you can make use of textile wastes to collect fog, suitable for the current circular economy model. This study hopes to further enrich the materials used for fog harvesting. [ABSTRACT FROM AUTHOR]

BACKGROUND AND OBJECTIVES: Jordan is among the most water-scarce countries in the world. The scarcity of water resources in Jordan is driving the development and advances of non-conventional water techniques that enable integrated management of water resources in addressing water scarcity challenges and promoting sustainable water use. Water harvesting of rainwater and fog techniques is one of the viable solutions to mitigate the water scarcity effects in Jordan. This study aimed to evaluate the quantity of rainwater and fog collected through the utilization of solar panels, while also conducting a feasibility analysis on the economic and environmental aspects of employing solar panels for rainwater and fog harvesting in a solar farm situated in Jordan.METHODS: In the present study, an in-situ experiment is conducted to investigate rainwater and fog harvesting from solar panels' surfaces that are widely spread in Jordan. The solar farm situated in Hai Al Sahabah, south of Amman, Jordan, incorporates an experimental arrangement that involves the installation of gutters, pipes, and water tanks beneath two solar panel samples. These panels have a total area of 4 square meters and will be monitored for a duration of 60 days.FINDING: The results of the experiment show that the total quantity of the harvested rainwater using two solar panels was 444 liters ranging from 0.8 liters per day to 117.66 liters per day, and the total harvested fog quantity was 28 liters ranging from 0.25 liters per day to 9.75 liters per day. The multilinear regression technique was employed to establish a correlation between the amount of harvested water and the crucial factors of wind direction, wind speed, relative humidity, and temperature at the solar farm. The analysis of the findings revealed a significant relationship between these variables. These relationships can be generalized to provide an estimation for the quantity of rainwater and fog harvesting in other locations. The quantity of harvested rainwater was primarily influenced by wind speed and direction, the quantity of harvested fog was mainly affected by relative humidity and temperature. The current study aims to analyze and deliberate on the collected amounts of water obtained through rainwater and fog harvesting from solar panels. The viability of implementing the method of rainwater and fog harvesting from solar panels will be examined in terms of economic and environmental factors.CONCLUSIONS: The quantity of rainwater gathered in this research with just two solar panels shows great potential for widespread use as a supplementary water supply. This method of rainwater and fog harvesting can be effectively applied to solar power plants which are widely spread in Jordan for use in solar panel cleaning, agriculture, groundwater recharge, and reducing stormwater discharge to assess and manage the risk of environmental damage. Rainwater and fog harvesting systems offer a higher level of efficiency and cost-effectiveness compared to other methods, especially when seamlessly integrated into the infrastructure of solar power plants. The benefits of solar panels by producing clean energy are not negotiable but combining energy production with water harvesting in solar power plants would offer even more advantages in enhancing the global environmental situation.

Freshwater scarcity has become a critical global challenge affecting some of the most vulnerable populations. In response, significant effort has focused on ways to increase access to this precious resource. Within the context of geographical, cultural, political, and technological factors governing freshwater availability, atmospheric water harvesting (AWH) has demonstrated tremendous promise to help address these shortages. Specifically, mesh‐based fog harvesters have received considerable attention for their passive qualities compared with their energy‐dependent technological siblings (sorbents, condensation, etc.), yet their specific water yield (SY) has developed only modestly in recent decades. While the plant and animal kingdom provide diverse examples of passive fog collection, and science has developed a remarkable understanding of these processes, much of this knowledge has yet to be translated practically at scale. This is partially due to challenges in mass‐producing complex (often micro‐scale) structures observed in nature. Fortunately, manufacturing technology is catching up with scientific understanding, especially at the scale of mesh design. To this end, the review begins by surveying bioinspired research in fog harvesting. Afterward, this study identifies milestones in developing bioinspired fog harvesting meshes, concluding in a discussion of future mesh research opportunities connecting bioinspiration and emerging advanced manufacturing techniques. [ABSTRACT FROM AUTHOR]

Drop-fiber interactions are fundamental to the operation of technologies such as atmospheric fog capture, oil filtration, refrigeration, and dehumidification. We demonstrate that by twisting together two fibers, a sliding drop's flow path can be controlled by tuning the ratio between its size and the twist wavelength. We find both experimentally and numerically that twisted fiber systems are able to asymmetrically stabilize drops, both enhancing drop transport speeds and creating a rich array of new flow patterns. We show that the passive flow control generated by twisting fibers allows for woven nets that can be "programmed" with junctions that predetermine drop interactions and can be anticlogging. Furthermore, it is shown that twisted fiber structures are significantly more effective at capturing atmospheric fog compared to straight fibers. [ABSTRACT FROM AUTHOR]

Surfaces with macro‐scale hydrophilic/hydrophobic regions (conventional Janus mode) are often considered as prime candidates for fog harvesting. However, the water collection efficiency of such surfaces frequently fails to meet the requirements of practical applications due to the occurrence of surface flooding caused by water droplet pinning. Here, an in situ molecular confined modification strategy is proposed to construct upgraded Janus mode for achieving nanoscale drag reduction effect, thereby improving the fog collection efficiency. Specifically, nanoscale hydrophilic sites are designed to effectively reduce the critical volume size required for water droplets to slide off, thus avoiding the surface flooding. Fibers with upgraded Janus mode (PAN‐TO) realize a water collection rate of 4035 mg cm−2 h−1, markedly exceeding that of most materials with conventional Janus mode. Moreover, the high interface bonding strength between hydrophilic sites and the material surface can withstand the impact of water and sand flushing, ensuring the long‐term usability of the material. The applications of PAN‐TO fibers in irrigation and dyeing are demonstrated. This work shows a nanoscale surface engineering proposal for building a next‐generation fibrous fog harvesting device. [ABSTRACT FROM AUTHOR]

Fog harvesting, also known as fog collection, is a sustainable approach to addressing water scarcity which captures water droplets from fog, providing a renewable water source for water-scarce regions. The aim of this study is to give more background about fog harvesting by introducing fog harvesting systems, their advantages and disadvantages, real world and laboratory projects and efficiency. This study emphasizes fog harvesting's potential in arid regions with frequent fog occurrence, discusses working mechanisms, and explores nature-inspired and nanotechnology-based fog collectors. Local climate data's importance for feasibility assessment is highlighted, along with the vital role of community involvement for long-term success. Fog harvesting offers a promising and environmentally friendly solution to alleviate water scarcity challenges when combined with innovative strategies and community engagement. Real-world projects have shown that fog water collection can be an effective and sustainable solution, particularly in regions with persistent fog and limited water resources. However, more work is needed on innovative fog collectors and advanced materials to increase sustainability. [ABSTRACT FROM AUTHOR]

With the rapid growth of the population and the development of the economy, the shortage of freshwater resources has become a worldwide problem. Utilizing fog harvesting provides a practical solution to relieve the water shortage problem for residents in arid regions. This review summarizes the typical fog harvesting phenomena in nature in detail, the construction methods, fog harvesting performance, and the action mechanism of different biomimetic micro‐nano structures from one‐dimensional (1D), two‐dimensional (2D), and three‐dimensional (3D) perspectives. The influence of surface micro‐nano structure and wettability on water harvesting performance is analyzed. Finally, the challenges and future development directions of multi‐scale micro‐nano surface controllable water harvesting technology are summarized and prospected, which provides a good idea for the design of bioinspired micro‐nanomaterials and promotes water harvesting from scientific research to practical application. [ABSTRACT FROM AUTHOR]

This study identifies important factors for designing an effective biomimetic paper-based fog harvesting substrate by examining the harvesting properties of different surfaces, including glass, polyethylene, and superhydrophobic paper. In laboratory-scale fogging tests, the wetting behavior of the substrates is characterized, and the importance of the tilt angle of the respective surface relative to the fog flow is elaborated. Because successful fog harvesting requires both efficient accumulation of water droplets on the surface (by condensation and collision) and sufficient but not excessive roll-off of the liquid, the amount of water finally collected is clearly related to the pinning effect, which should prevent the smallest droplets from being carried away by the wind but must not lead to full and permanent wetting of the surface. Coalescence is identified as a major phenomenon to improve droplet roll-off. In this context, superhydrophobic paper indicates to be a more effective water collector than glass or polyethylene, especially when oriented vertically, since it allows the droplets to roll off very efficiently. Finally, the addition of glass particles to the superhydrophobic coating is proposed as a means of enhancing pinning and improving the fog harvesting efficiency. [ABSTRACT FROM AUTHOR]

Water is a vital component for all living organisms, yet persistent water scarcity remains a global challenge. One potential solution lies in replicating the atmospheric water collection mechanism observed in the Stenocara beetle, characterized by a dorsal surface featuring alternating hydrophilic and hydrophobic regions. In this study, we have designed and examined two distinct biphilic patterned surface configurations, integrating various technologies, to mimic the beetle's water collection strategy. Our investigation evaluates the efficiency of these surfaces in both capturing water from fog and condensing water from dew. For fog collection two parameters were the most impactful: the roughness and the wettability contrast between hydrophilic and hydrophobic zones. In contrast, dew condensation was influenced by additional parameters notably the patterns' size and density that directly affect the water contact angle. It is worth noting, however, that the optimal surface for fog collection may not necessarily coincide with the most effective surface for dew condensation. Furthermore, our research includes a comparative analysis between the theoretically predicted volume of water droplet departure and the empirically observed results.

This research aims to explore the use of vegetation and nets to collect water from fog on facades to meet the needs of buildings' functional requirements, particularly outdoor thermal comfort, water demands, and encouraging sustainability by suggesting a new architectural green–blue wall system. The system is posited to be applicable within an urban context, given its minimal spatial requirements and adaptability to existing structures. However, similar challenges to those encountered by green walls are anticipated, wherein the provision of sustainable benefits is offset by the demands of maintenance and associated additional costs. For this reason, this paper is mainly divided into two parts: in the first part, green facades are explained, referring to their effect on urban environment, including thermal comfort, pollution absorption, noise pollution, and well-being, as well as types of plants to apply on green walls; the second part focuses on the fog collector as an irrigation system for green walls, analyzing its components, structure, and fabric, to identify its development margins in the construction industry. Fog harvesting initiatives predominantly focus on rural regions to cater to agricultural demands; however, limiting fog harvesting to agricultural settings is considered insufficient, as it represents a crucial solution for addressing water challenges in specific urban environments. Nevertheless, it is worth investigating the fog collector's potential for integrating water supply in urban environments as well. The study focuses on exploring the environmental benefits of fog harvesting and green walls, particularly through their combined implementation. The proposed review is significant for guiding the integration of a device into green facades, ensuring water self-sufficiency while concurrently addressing air purification, noise reduction, and thermal comfort for pedestrians and urban inhabitants. Nevertheless, it is worth investigating the fog collector's potential for integrating water supply in urban environments as well. The proposed review is, therefore, useful for integrating a device represented by the fog harvesting system, also identified in the text as the blue system, into the design of green facades, identified in the text as the green system, integrating the blue element in the design of the green wall to make them water self-sufficient and at the same time purifying the air, reducing noise pollution, or giving thermal comfort to pedestrians and inhabitants of the urban context. [ABSTRACT FROM AUTHOR]

The most valuable resource for sustaining life on earth is water. In dry and semi-arid areas, the problem of water scarcity can be resolved with the aid of fog collection techniques employing fog collectors. Fog collection is greatly influenced by a variety of factors. Some are design parameters, while others depend on ambient circumstances. Geometry and the mesh's shade coefficient are important design factors that can be modified and have an impact on the rate at which fog collects in fog collectors. The shape of the mesh holes and the process used to create the mesh serve to identify geometry and measure the shade coefficient. In this paper, a straightforward mathematical technique is proposed to make it easier to calculate the shade coefficient of various mesh shapes used in fog harvesting and to provide an approximation of the mesh volume and cost. Five alternative geometries were used: the rectangular mesh, square mesh, Raschel mesh, triangular mesh, and hexagonal mesh. The current simple method will facilitate the design of the fog mesh collector and can assist in achieving the ideal shade coefficient and most effective mesh geometry for fog harvesting. Rectangular meshes were solely used as an example to evaluate the results. Stainless steel rectangular meshes with various shade coefficients were tested for fog collection, and the amount of water collected by each mesh varied. It was concluded that the optimum shade coefficient ranged 50–60% for fog collection. [ABSTRACT FROM AUTHOR]

Abstract This study identifies important factors for designing an effective biomimetic paper‐based fog harvesting substrate by examining the harvesting properties of different surfaces, including glass, polyethylene, and superhydrophobic paper. In laboratory‐scale fogging tests, the wetting behavior of the substrates is characterized, and the importance of the tilt angle of the respective surface relative to the fog flow is elaborated. Because successful fog harvesting requires both efficient accumulation of water droplets on the surface (by condensation and collision) and sufficient but not excessive roll‐off of the liquid, the amount of water finally collected is clearly related to the pinning effect, which should prevent the smallest droplets from being carried away by the wind but must not lead to full and permanent wetting of the surface. Coalescence is identified as a major phenomenon to improve droplet roll‐off. In this context, superhydrophobic paper indicates to be a more effective water collector than glass or polyethylene, especially when oriented vertically, since it allows the droplets to roll off very efficiently. Finally, the addition of glass particles to the superhydrophobic coating is proposed as a means of enhancing pinning and improving the fog harvesting efficiency.

Access to clean drinking water is a critical need for human societies. Intercepting atmospheric fog can help collect water from the atmosphere, even in situations of high-water scarcity in fog-prone areas. Metal meshes or screens are commonly used as fog collectors, where the mesh surfaces are often engineered to enhance water collection rates. Despite significant work over the past several decades, the ideal surface wettability desired in terms of surface roughness and functionalization for efficient fog harvesting is not well understood. The volume of water collected depends on the proportion of fog intercepted by the meshes and how effectively the deposited water droplets drain off into the collector. In this work, we employ scalable surface treatments such as chemical etching and atmospheric pressure vapor deposition on stainless steel meshes to alter the surface wettability. We evaluate the efficacy of fog harvesting on the wettability altered meshes, and compare their performance against untreated stainless steel meshes. We further investigate the effect of surface ageing on the wettability and fog collection performance. Our work not only offers valuable design guidelines for the development of effective fog collectors but also highlights the significant influence of the atmosphere in controlling wetting behaviour.

Fog harvesting from the air is one of the sustainable and effective methods to obtain fresh water. Energy-free fog collector systems are widely used for this purpose, but the efficiency of traditional meshes used in these systems is not sufficient. The main objective of this study is to transform ordinary polypropylene fabrics into effective fog harvesting materials by coating them with polymeric thin films using plasma-enhanced chemical vapor deposition (PECVD), which is a one-step and environmentally friendly method. Poly(acrylic acid) (PAA) and poly(2,3,4,4,4-hexafluorobutyl acrylate) (PHFBA) thin films were synthesized using PECVD method as hydrophilic and hydrophobic polymers, respectively. In this study, the effects of surface wettability and fabric weight on fog harvesting efficiency were investigated. Moreover, the effect of surface roughness on fog harvesting efficiency was studied by modifying of the fabrics with silica particles before PECVD coating. The fabrics obtained with hydrophobic thin-film coating on roughened surface showed the highest fog harvesting efficiency (1.14 L/m2.h). The results of this study show that the fabrics modified by the method developed here can be a promising alternative to the meshes currently used in fog collector. [ABSTRACT FROM AUTHOR]

Fog-harvesting performance is influenced by surface wettability, patterned structure and the heat transfer coefficient. In this work, we have prepared different surfaces with a stripe array of superhydrophilic, superslippery and superslippery/superhydrophilic surfaces for fog harvesting on silicon substrates using photolithography and silver-assisted chemical etching. The surface wettability and heat transfer coefficients of the above samples have been investigated. We analyzed the contact angle, sliding angle and transport state of droplets on these surfaces. The fog-harvesting rate of all samples under different voltages of the cooling pad (V = 0, 2.0, 2.5, 3.0, 3.5 V) was measured. Results showed that the superslippery/superhydrophilic striped surface could achieve rapid droplet nucleation, directional transport and efficient collection due to its superhydrophilic striated channels and the Laplace pressure difference between different wettability regions. At a condensation voltage of 3.5 V, the fog-harvesting rate efficiencies of the uniformly striped superhydrophilic and superslippery surface were 1351 mg·cm−2·h−1 and 1265 mg·cm−2·h−1, respectively, while the fog-harvesting rate of the superslippery/superhydrophilic striped surface was 1748 mg·cm−2·h−1. Compared with the original silicon surface, the maximum fog-harvesting rate of the superslippery/superhydrophilic striped surface was improved by 86.9%. This study offers significant insights into the impact of heat transfer and silicon surface wettability on the process of fog collection. [ABSTRACT FROM AUTHOR]

Water scarcity is a pressing global challenge which must be addressed promptly with sustainable solutions. This essay discusses fog harvesting as a promising supplemental water source in the coastal regions of South America. Fog harvesting proves to be a highly cost-effective and energy-efficient solution, providing access to water to communities in geographically challenging areas. Various factors affecting its efficiency are explored, while highlighting the need for research and development in the field to maximize its potential and enhance long-term water security.

By 2050, more than 50% of the world’s population will face water stress. Global demand for drinking water will also increase due to economic development, population growth and other needs. To alleviate this growing problem, the scientific community is called upon to explore all potential water resources and develop appropriate technologies. One such promising resource is fog, especially when climatic conditions are favorable and nearby conventional resources are insufficient. The present bibliometric study is an attempt to explore the topic of “fog harvesting” and understand the dynamics in this area. Indeed, three significant directions have been identified: 1- materials, their properties and characteristics; 2- biological mimicry to collect fog; 3- interaction with other nearby issues (energy, solar, desalination, etc.). In summary, “fog harvesting” is a relatively premature but promising area of research. Due to the strong dependence on climate and topography, this area is still hesitant in terms of collaboration. This may be a good avenue to explore.

Easy-implement and low-cost fabrication of super-hydrophobic/super-oleophobic materials is of great significance for efficient fog harvesting. Herein, we propose a simple two-step procedure based on Cu/1-octadecanethiol (ODT) self-assembled monolayer (SAM) modified zinc plates. Interestingly, the whole process mimics the blooming process of flowers in nature: the deposition of copper particle and the subsequent formation of SAM drives the surface undergo gradually stretches and finally blooms to camellia-like nanostructures. The water contact angle (WCA) and oil contact angle (OCA) reach 160 ± 1° and 159 ± 1° respectively, as a result of the formation of layered petal structure that traps air effectively, which is attributed as one of the most important factors for the superamphiphobic effect. In addition to much enhanced facility in fog collection, the materials maintain excellent performance in acid/base environments (1 ≤ pH ≤ 14), broad temperature conditions ranging from −18 °C to 240 °C, and the artificial sea environment, and exhibit capable wear resistance as well as self-cleaning property. The cooperation of all these multiple properties ensures the robustness and stability for efficient fog collection.

Bio‐inspired fog harvesting devices (FHDs) have been exploited to address water shortages. Despite the advances achieved, efficient and continuous fog harvesting is still hindered by some challenges: 1) a single mechanism appears to be insufficient to achieve optimal water collection efficiency; 2) the re‐evaporation of the harvested water results in decreased water collection. In this study, inspired by the unique feature of cacti, Nepenthes alata, lotus leaves, and pinecones, a 2D–3D switchable copper sheet (SLP‐SHL@SP‐Cu) is reported, which results in excellent fog capture and water transport rates. During the fog harvesting process, the captured droplets transport from the tip of the top surface to the bottom under the Laplace forces (cacti spine), capillary forces (lotus leaves), and low surface energy (Nepenthes alata). Notably, the novel FHD responds in a preprogrammed manner to changes in humidity and performs a dynamic transformation from a 2D planar structure to a 3D helical structure (and in reverse), enabling efficient fog harvesting (in the 3D geometry) and water storage (in its 2D form). Thus, this study opens a new avenue for the practical applications of highly effective FHDs with increased water retention abilities. [ABSTRACT FROM AUTHOR]

Multimaterial surfaces with hierarchical features have many potential applications in self‐cleaning, droplet manipulation, microfluidics, and biomedicine, owing to their wide range of functionalities induced by structural and material contrasts. Here, a fast and sustainable manufacturing method, acoustic assembly photopolymerization (AAP), is presented for productions of such surfaces. In the novel AAP process, an external acoustic field is used to assemble microparticles to microsized patterns, while the photocuring is combined with the acoustic assembly to produce multilevel hierarchical features, such as cones and wrinkles ranging from nanometer to micrometer. The mechanism underlying the proposed multimaterial surface structuring technique is discussed, and the relationship between process parameters and surface structures is modeled. Effects of surface material composition patterns and surface topology on the hydrodynamic properties are studied. To demonstrate potential applications, three microreactors are designed and automated droplet manipulations are demonstrated. The application of the proposed surface manufacturing approach is further extended to fog harvesting. The AAP technology and the fabricated multimaterial hierarchically‐structured surfaces demonstrated in this study can be employed in many other advanced applications in microfluidics, tissue engineering, and also potentially many other fields such as mechanical systems and battery systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • Janus membrane with heterogeneous wettability top surface for fog collection. • Spray coating strategy to prepare surfaces with heterogeneous wettability. • Paraffin loading on the morphology and permeability is systematically investigated. • The mechanism of drop one-way penetration on the Janus membrane is revealed. • The unique fog deposition-grow-sucking collection and mechanism investigated. To alleviate the global water scarcity crisis, fog harvesting has seen considerable development as a promising strategy. However, the current main challenge lies in achieving efficient fog deposition, timely transport of water droplets, and storage. Here, inspired by clusters of cactus trichomes and sponges, a Janus membrane with heterogeneous wettability top surface (JM-HWTS) is proposed. The JM-HWTS was obtained by spraying paraffin wax particles (hydrophobic) on the copper mesh top surface (superhydrophilic). The relationship between the loading amount of paraffin particles and the surface morphology, water permeability, and one-way penetration ability of the sample was clarified. Compared to fog collection surfaces with single hydrophilic or hydrophobic properties, the proposed JM-HWTS system significantly increased fog collection efficiency. For JM-HWTS, the fog will first deposit into water droplets on the hydrophobic front side, then grow up, and finally be sucked into the hydrophilic back side. This unique cyclic fog collection method is the key to efficient fog collection. The JM-HWTS exhibits excellent water-collection efficiency, enabling efficient capture of fog and rapid directional delivery of droplets. This work will significantly complement the fog collection and water droplet storage fields. [ABSTRACT FROM AUTHOR]

Abstract Multimaterial surfaces with hierarchical features have many potential applications in self‐cleaning, droplet manipulation, microfluidics, and biomedicine, owing to their wide range of functionalities induced by structural and material contrasts. Here, a fast and sustainable manufacturing method, acoustic assembly photopolymerization (AAP), is presented for productions of such surfaces. In the novel AAP process, an external acoustic field is used to assemble microparticles to microsized patterns, while the photocuring is combined with the acoustic assembly to produce multilevel hierarchical features, such as cones and wrinkles ranging from nanometer to micrometer. The mechanism underlying the proposed multimaterial surface structuring technique is discussed, and the relationship between process parameters and surface structures is modeled. Effects of surface material composition patterns and surface topology on the hydrodynamic properties are studied. To demonstrate potential applications, three microreactors are designed and automated droplet manipulations are demonstrated. The application of the proposed surface manufacturing approach is further extended to fog harvesting. The AAP technology and the fabricated multimaterial hierarchically‐structured surfaces demonstrated in this study can be employed in many other advanced applications in microfluidics, tissue engineering, and also potentially many other fields such as mechanical systems and battery systems.

The scarcity of useable water is severe and increasing in several regions of the Middle East, Central and Southern Asia, and Northern Africa. However, the earth's atmosphere contains 37.5 million billion gallons of water in the invisible vapor phase with fast replenishment. The United Nations Convention to Combat Desertification reports that by 2025 about 2.4 billion people will suffer from a lack of access to safe drinking water. Extensive research has been conducted during the last two decades to develop nature-inspired nanotechnology-based atmospheric water-harvesting technology (atmospheric water generator, AWG) to provide clean water to humanity. However, the performance of this technology is humidity sensitive, particularly when the relative humidity (RH) is high (>~80% RH). Moreover, the fundamental design principle of the materials system for harvesting atmospheric water is mostly unknown. In this work, we present a promising technology for solar energy-driven clean water production in arid and semi-arid regions and remote communities. A polymeric electrospun hybrid hydrogel consisting of deliquescent salt (CaCl2) and nanomaterials was fabricated, and the atmospheric water vapor harvesting capacity was measured. The harvested water was easily released from the hydrogel under regular sunlight via the photothermal effect. The experimental tests of this hybrid hydrogel (PAN/AM/graphene/CaCl2) demonstrated the feasibility of around 1.04 L of freshwater production per kilogram of the hydrogel (RH 60%). The synergistic effect enabled by photothermal materials and deliquescent salt in the hydrogel network architecture presents controllable interaction with water molecules, simultaneously realizing efficient water harvesting. This technology requires no additional input of energy. When considering the global environmental challenges and exploring the available technologies, a sustainable clean water supply for households, industry, and agriculture can be achieved from the air using this economical and practical technology. [ABSTRACT FROM AUTHOR]

Water scarcity in many countries on earth has inspired scientists to seek other resources of freshwater. Desalination, as one of the most commonly used approaches, is energy consuming and has faced a number of environmental difficulties. On the other hand, natural species, plants and insects, have developed their own modalities of securing fresh water by harvesting it from the atmospheric fog and humidity. The current study investigates the fabrication of bioinspired mesh membranes for fog harvesting. The mesh membranes are coated using a simple dip coating procedure with various extents of TiO2‐PMMA hybrid structure that provides a composite structure of mixed degrees of wettability. Depending on the initial concentration of PMMA, partially and completely covered mesh membranes were prepared. The coated mesh membranes resemble Spider silk in their architecture and in their surface topography to other desert natural species. A homogeneous distribution of the TiO2 NPs within the PMMA coating was reflected on a spectrum of hydrophilic and hydrophobic domains. The fabricated mesh membranes are durable and have been shown to harvest water from fog at a rate of 32–45 L/m2 per hour, hence securing a sustainable supply of fresh water for all aspects of life. [ABSTRACT FROM AUTHOR]

Slippery lubricant-infused surfaces exhibit excellent fog-harvesting capacities compared with superhydrophobic and superhydrophilic surfaces. However, lubricant depletion is typically unavoidable under dynamic conditions, and reinfused oil is generally needed to recover the fog-harvesting capacity. Herein, an effective strategy for delaying the depletion of lubricant to prolong the service life of fog harvesting is proposed. An ultrathin transparent lubricant self-replenishing slippery surface was fabricated via facile one-step solvent evaporation polymerization. The gel film of the lubricant self-replenishing slippery surface, which was embedded with oil microdroplets, was attached to glass slides via the phase separation and evaporation of tetrahydrofuran. The gel film GFs-150 (with oil content 150 wt% of aminopropyl-terminated polydimethyl siloxane (PDMS-NH2)) exhibited superior slippery and fog-harvesting performance to other gel films. Furthermore, the slippery surfaces with the trait of oil secretion triggered by mechanical stress exhibited better fog-harvesting capabilities and longer service life than surfaces without the function of lubricant self-replenishment. The lubricant self-replenishing, ultrathin, and transparent slippery surfaces reported herein have considerable potential for applications involving narrow spaces, visualization, long service life, etc. [ABSTRACT FROM AUTHOR]

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Water scarcity is a critical global challenge, especially in arid and semiarid regions. Fog harvesting has emerged as a promising solution; however, concerns about air pollution and bacterial growth in humid environments have raised doubts about the safety and sustainability of such systems. This study introduces a Janus mesh with asymmetric wettability on its two faces, fabricated through a simple and scalable method. The unique design of the Janus mesh enables the transport of water droplets from the superhydrophobic side to the hydrophilic side in a unidirectional manner, enhancing its fog harvesting efficiency. The mesh's photocatalytic properties not only elevate the fog harvesting rate to 4.7 kg·m -2 h -1 but also effectively purify the harvested water by removing organic contaminants (94%) and microbial impurities (99.98%). Additionally, its inherent bactericidal activity prevents biofouling, ensuring sustained efficiency in water collection. The mesh's self-cleaning abilities through photocatalysis maintain its surface integrity, promising long-term stability for fog harvesting applications. This technological advancement in fog harvesting offers a sustainable and economical solution to water scarcity concerns, addressing safety and sustainability issues associated with existing systems. By potentially transforming the livelihoods of communities struggling with water scarcity, this innovation paves the way for a more sustainable future.

The urgent need for sustainable energy storage drives the fast development of diverse hydrogen production based on clean water resources. Herein, a unique type of multi-bioinspired functional device (MFD) is reported with asymmetric wettability that combines the curvature gradient of cactus spines, the wetting gradient of lotus, and the slippery surface of Nepenthes alata for efficient fog harvesting. The precisely printed MFDs with microscale features, spanning dimensions, and a thin wall are endowed with asymmetric wettability to enable the Janus effects on their surfaces. Fog condenses on the superhydrophobic surface of the MFDs in the form of microdroplets and unidirectionally penetrates its interior due to the Janus effects, and drops onto the designated area with a better fog harvesting rate of 10.64 g cm -2 h -1 . Most significantly, the collected clean water can be used for hydrogen production with excellent stability and durability. The findings demonstrate that safe, large-scale, high-performance water splitting and gas separation and collection with fog collection based on MFDs are possible., (© 2024 Wiley‐VCH GmbH.)

Fog harvesting represents a promising strategy to address the global freshwater shortage. To enhance the water collection efficiency, diverse geometric structures that can effectively drive water droplet movement are essential. Inspired by the Livistona chinensis leaf, which naturally facilitates directional droplet motion through its unique gradually varying V-groove structure, we have developed a novel origami fan structure for fog harvesting through theoretical analysis. A key feature is that we can modulate the speed of droplet transport by adjusting the opening angle of the V-shaped grooves positioned at the outer circumference. Interestingly, the water collection efficiency exhibits a linear correlation with the opening angle. The highest efficiency of the origami fan can reach 5.75 times that of the control group calculated by the projected area and 3.76 times that of the control group calculated by the real area, showcasing its significant potential for enhancing water collection from fog. The simulations demonstrate that the hollow structure enhances the condensation rate of droplets, the geometric gradient of the gradual-variation V-groove drives the condensed droplets to move rapidly on the surface, and the Janus membrane permits the aggregated droplets to transit to the fan's rear side. The synergistic action of these three components ensures a clean surface for the subsequent water-collecting cycle, contributing to the high fog-harvesting efficiency. Given its simple fabrication and superior water transfer efficiency, the origami fan holds substantial promise for widespread application in the field of droplet manipulation.

Fog collection is a promising solution for mitigating the urgent water shortage around the world. Despite the delicate design of various bionic fog harvesting surfaces with prowess to enable fast fog capture and programmed water transport, achieving sustainable and efficient fog collection by regulating the macroscale surface refreshment efficacy remains rarely concerned yet is effective. Here, we proposed a bioinspired structural design to achieve significant improvement on the surface refreshment efficacy to 46.47%, nearly 5 times larger than that of conventional design. Specifically, we constructed superhydrophilic vein-like microchannels on a superhydrophobic brass surface by using laser texture technology and hydrothermal treatment. Our microchannel design acts as a "highway" for synergically transporting and converging the collected fog droplets, as well as rapidly refreshing large surface area for the subsequent fog collection, reminiscent of the leaf veins responsible for the persistent mass transport between plant tissues. The practical implementation also convinced our design of a maximum water collection efficiency of up to 506.67 mg cm -2 h -1 and a long-term performance stability within a 10 h test. Our design is generic to most of the fog harvesting materials, showing great application potential for efficient atmospheric fog collection.

The conventional Slippery Liquid Infused Porous Surface (SLIPS) encounters challenges such as silicone oil leakage and complex manufacturing of rough substrate structures. Thus, it is crucial to develop a lubricant that is highly adaptable and less prone to loss for surface structures; a temperature-controlled method of infusing oleogel into a superhydrophobic surface (SHS) is presented in this paper. This approach draws inspiration from the characteristics of Nepenthes pitcher plant structures, albeit without the need for intricate pore-making or nanowire structures. It is demonstrated that this resulting surface has exceptional fog harvesting capability, with a fog harvesting efficiency of 0.3222 g cm -2 min -1 , which is twice as high as that of the laser aluminum (Al) sheet (0.1553 g cm -2 min -1 ). Moreover, the surface exhibits remarkable anti-icing properties, significantly prolonging the icing time by 21-fold compared to the pure Al sheet while maintaining a minimal ice adhesion force of only 0.16 N. Additionally, the surface showcases excellent antifouling performance, because contaminated droplets readily slide off without leaving residue. The environmentally friendly and straightforward preparation process ensures that it is suitable for large-scale industrial applications., (© 2024 Wiley‐VCH GmbH.)

Fog-harvesting performance is influenced by surface wettability, patterned structure and the heat transfer coefficient. In this work, we have prepared different surfaces with a stripe array of superhydrophilic, superslippery and superslippery/superhydrophilic surfaces for fog harvesting on silicon substrates using photolithography and silver-assisted chemical etching. The surface wettability and heat transfer coefficients of the above samples have been investigated. We analyzed the contact angle, sliding angle and transport state of droplets on these surfaces. The fog-harvesting rate of all samples under different voltages of the cooling pad (V = 0, 2.0, 2.5, 3.0, 3.5 V) was measured. Results showed that the superslippery/superhydrophilic striped surface could achieve rapid droplet nucleation, directional transport and efficient collection due to its superhydrophilic striated channels and the Laplace pressure difference between different wettability regions. At a condensation voltage of 3.5 V, the fog-harvesting rate efficiencies of the uniformly striped superhydrophilic and superslippery surface were 1351 mg·cm−2·h−1 and 1265 mg·cm−2·h−1, respectively, while the fog-harvesting rate of the superslippery/superhydrophilic striped surface was 1748 mg·cm−2·h−1. Compared with the original silicon surface, the maximum fog-harvesting rate of the superslippery/superhydrophilic striped surface was improved by 86.9%. This study offers significant insights into the impact of heat transfer and silicon surface wettability on the process of fog collection.

The increasing demand for clean water driven by the rapid growth of the population and the pollution of water necessitates the development of direct and rapid water harvesting methods. Fog harvesting is proven as a highly efficient water capture method in dry but foggy areas. Herein, the state‐of‐the‐art developments on the multiple biomimetic fog harvesting devices (FHDs) are presented. First, the fundamental and specific mechanisms of fog harvesting involving the Namib Desert beetle, spider silk, cactus, and Nepenthes alata are described in detail, respectively. Second, an in‐depth discussion on the mechanisms of fog harvesting including fog capture and water transport is proposed. Third, a detailed account of the innovative design strategies and fabrication technologies of FHDs is proposed, from single to multiple biomimetic FHDs with typical examples and the merits and demerits are compared. Finally, a critical analysis of current challenges and future development is presented, aiming to promote next‐generation FHDs from scientific research to practical application. [ABSTRACT FROM AUTHOR]

Abstract Fog harvesting is an unconventional source of water that can be used in some regions with water scarcity to overcome water shortages. The most commonly used collectors are meshes which have intrinsic limitations, the most important of which are clogging and aerodynamic deviation of droplets around the wires. Here, three techniques are compared and combined to overcome these limitations, i.e., replacing the mesh with an array of vertical wires, addition of a hydrophobic layer to the wires, and forcing the ionized droplets to move toward the wires by applying an electric field. The combination of these techniques was found to result in higher fog harvesting efficiency compared to each individual method with the highest impact from the addition of the electric field. The combined methods lead to a 60-fold increase in fog harvesting efficiency compared to meshes. The findings showed that when the fog droplets are forced in an electric field toward the wires, the shading coefficient for collectors can be increased to 1 from 0.55 (maximum for collectors without the electric field) without affecting the fog harvesting efficiency, allowing for lower construction cost of the collectors. Addition of the electric field showed two distinctive promotional effects. First, increasing the aerodynamic efficiency and second, reducing the size of droplets sliding down the wires by disturbing the three-phase contact line and reducing the contact angle hysteresis and the pinning force. Energy analysis shows that this technique can be 100 times more energy efficient compared to the conventional atmospheric water generators.

Water collection from atmospheric fog was deemed to be an efficient and sustainable strategy to defuse the freshwater scarcity crisis. Fog harvesting and trapping fibers, therefore, has aroused extensive interest due to their ease of preparation, weave, and use. However, the traditional fibers used in fog collector usually have a low fog collection capacity and efficiency because of their unreasonable morphology and structure design. Herein, we proposed a simple process to construct advanced fibers using a one-step wet spinning of hydrophobic polyvinylidene fluoride (PVDF) and hydrophilic cellulose mixture fiber for fog harvesting. The as-prepared fibers featured a petaloid structure and surface hydrophobic gradient, thus facilitating fog deposition, water droplet formation, and drainage. The unique longitudinal groove structure above enabled the hybrid fiber to achieve an excellent fog collection efficiency of 2750.26 mg/cm2/h per monofilament, which outstripped most of other fiber materials. When woven these fibers were in a longitudinal array network with an interval of 1 mm, and the fog collection efficiency can maintain at 10.30 L/m2/h. Therefore, this work provided a new strategy for further exploration of effective fog collection by cellulose-based fiber materials. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A conical shaped self-healing slippery film with tunable cone angles is fabricated via simple template method and Chinese traditional origami craft. • The advantage of conical structure on preventing droplets splashing in windy condition is demonstrated. • The scratches of different widths on the fabricated film surface can be quickly repaired under solar illumination. Wind presents both advantages and disadvantages for water collection. It can bring an abundant fog resource to arid areas for water harvesting, however, some of the captured water droplets are inevitably blown away in a windy environment because of the easy-sliding property of the material surface. Herein, a conical-shaped, self-healing, liquid-infused film with tunable cone angles based on candle soot, thermoplastic poly (ethylene-co-vinyl acetate) (EVA), and hydrophobic silicone oil has been developed using a simple template method and traditional Chinese origami. Benefiting from the inward force induced by the conical structure, the condensed droplets prefer to gather toward the top of the conical structure in windy environments rather than splashing out, which usually occurs on a plane surface. This advantage can greatly ensure the high water collection efficiency of materials in windy regions. In addition, owing to the unique photothermal property and thermoplasticity of the designed conical structure, surface scratches during application can be quickly repaired under solar illumination without extra fossil energy consumption, and long-term stable application of the materials can be guaranteed. Therefore, this study finely synergized structure design and performance enhancement and established a new paradigm for effective and reliable fog harvesting applications. [ABSTRACT FROM AUTHOR]

Ongoing climate change and anthropogenic impacts will continue to worsen the problem of water crisis. In order to explore practical solutions for drought and climate change adaptation, this work uses a set of different methodologies to evaluate an operational fog collection project and discuss solutions for some emerging challenges. This study uses fog collection rate, Water Quality Index (WQI) and interviews with the community as indicators for the assessment. Results indicate that the project continues to deliver improved drinking water access to the community. Fog harvesting rate yielded an annual average from 1.6 to 6 L/m2/d. Interviews confirm the social commitment of the local community. However, challenging points emerge: (1) ongoing groundwater pollution due to the lack of sanitation; (2) if fog water is the only source, inconsistent fog yields may negatively impact water availability; (3) poor solid waste management. The findings represent a baseline for assessing and benchmarking other similar projects or project proposals in the Atlantic coast of North Africa. Therefore, the proposed methodology can also be used in other fog collection projects around the world. [Display omitted] • Sidi Ifni project, Morocco, is the largest fog collection project in the world. • A pilot multi-aspect assessment procedure is proposed. • The fog harvesting rate yielded an annual average of 1.6–6 L/m2/d. • Interviews confirm the technology appropriation by the local community. • Environmental pollution and fog yield variability represent the main challenge. [ABSTRACT FROM AUTHOR]

Collecting water from the fog becomes a promising strategy to address the water shortage. In this work, the CoO nanoneedle hierarchical structure was designed and prepared on the surface of the copper mesh by hydrothermal synthesis. The number of nanoclusters on the CoO nanoneedle array was changed by adjusting the mass concentration of the precursor solution. CoO nanoneedle array and nanoclusters form a hierarchical structure, which is conducive to the binding of air and the aggregation of water droplets. The results show that the surface of CoO nanoneedle hierarchical structure with good orientation and moderate sparsity has weak adhesion and stronger air binding capacity. Compared with other CoO nanoneedle structures, the hierarchical structure can effectively maintain the Cassie state wetting model for a long time, which improves the fog harvesting efficiency. This research offers a new strategy to design nanostructures for efficient fog collection, which has important implications on water harvesting from the air. Inspired by the surface structure of cactus, CoO nanoneedle hierarchical structure was obtained by hydrothermal synthesis on the surface of copper mesh for fog collection. By adjusting the conditions of hydrothermal synthesis, the hierarchical structure with good orientation and moderate sparsity can maintain the Cassie state wetting model for a long time, which effectively promotes the falling speed of water droplets and improves the efficiency of fog collection. [ABSTRACT FROM AUTHOR]