Desert Beetle Research Articles

Biomimetic Superhydrophobic Triboelectric Surface Prepared by Interfacial Self‐Assembly for Water Harvesting

AbstractExtracting water from air offers a promising route to address the global challenge of water scarcity. However, bionic engineering surfaces for water harvesting often struggle with efficiently coordinating droplet nucleation and desorption. The recently emerging triboelectric effect at the liquid–solid interface offers a novel approach for developing bionic fog harvesting surfaces. In this study, inspired by Namib Desert beetles and lotus leaves, a biomimetic superhydrophobic surface with nanoscale hydrophilic domains is prepared via interfacial self‐assembly, exhibiting heterogeneous wettability for effective water harvesting. The essence of interfacial self‐assembly lies in the synergy of non‐covalent interaction forces, driving the self‐assembly of nanoparticles into surface micro‐nano hierarchical structures, thereby regulating wettability and increasing potential nucleation sites. Additionally, the triboelectric effect can directly utilize the triboelectric charges to facilitate droplet migration. The triboelectric effect can be generated by flexible mechanical input induced by walking, which enhances interfacial mass transfer, thereby rapidly improving droplet removal and achieving a 39.02% increase in water harvesting efficiency. This study has opened up a new breakthrough for the design of portable and efficient water harvesting systems.

A Novel-Potential Wave-Bump Yarn of Plain Weave Fabric for Fog Harvesting.

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.

Diatoms Inspired Green Janus Fabric for Efficient Fog Harvesting

AbstractFog harvesting is a promising path against the global freshwater scarcity. Asymmetric wettability fabric‐based fog collection materials inspired by the Namib desert beetle have been reported widely due to their easy access and adjustable structures. Nevertheless, the single drive force for water transportation produced by the asymmetric wettability is insufficient, causing a non‐ideal fog harvesting efficiency. Moreover, sustainability challenges persist for fog collection materials, primarily due to their heavy dependence on chemical treatments. Herein, a diatom‐inspired Janus fabric (Ly/Csp‐3) based on asymmetric wettability and aperture gradient is developed without additional physical or chemical treatment. The wettability gradient and aperture gradient generate dual directional drive forces that regulate the water transport direction more accurately and enhance the transportation rate more effectively. Ly/Csp‐3 reaches a one‐way transport index of 390.7% and a water collecting rate (WCR) of 1170.5 mg cm−2 h−1, while exhibiting the capability of anti‐acid rain and the resistance to sunlight. This work provides an efficient and programmable biomimetic design proposal for fibrous fog harvesting devices.

Design of nature-inspired patterns on knitted fabrics for directional transportation of sweat and study of their performances

The human body in a hot environment or during intense training will sweat a lot. Traditional cotton fabrics are soft and breathable, but they tend to absorb moisture easily and evaporate it slowly, which makes people feel cold and wet. Sweat staying on fabrics for a long time could also cause bacteria to grow. Thus, it is necessary to transport the excessive sweat from the gathering section to the collection points along the surface paths in time to minimize such problems. The mechanism of directional water transport of desert beetles, cacti, nepenthes, and river meanders was referenced in this paper. The paths in dot, tree, V-shape, and river meander patterns were designed and manufactured from the inspiration of these natural architectures. The paths were coated on the surfaces of selected knitted fabrics with different structures through a one-step coating process. The optimal recipe of hydrophobic solution was determined when 0.1 g hydroxyethyl-cellulose (HEC) was added into MS-S002 solution. The results showed that sweat movement is mainly influenced by FL, FWD, FG, and knitted structure. The continuous and enclosed paths such as tree and river contribute to a better sweat moving track than those of dot and V-shape ones. Terry structure is more suitable for surface sweat transport than plain and pique. The highest movement speed of the terry structure with a tree pattern reaches 0.43 cm/s, followed by that of the terry structure with river pattern 0.35 cm/s. The coated fabrics also have ideal moisture and air permeability for wearing.

Water collection through a directional leaf vein pattern by fast laser marker ablation of stainless-steel

Inspired by the natural water harvesting mechanisms of desert beetles, cactus thorns, and leaf veins, we designed a heterogeneous wettability surface with superhydrophilic pattern integrating leaf vein as the directional water transport main channel, attached capillary triangles as auxiliary channel plus a deep rough desorption channel on an overall superhydrophobic surface for an efficient water collection. A superhydrophilic surface was initially fabricated on the stainless steel disc by laser marker ablation allowing 1 μL droplet to spread completely to 0° within 0.12 seconds, followed by fluorine-containing coating transforming superhydrophilic surface to superhydrophobic one. Directional water transport patterns were then etched on the superhydrophobic surfaces by the secondary laser marker. The surface energy gradient and Laplace pressure induced by the pattern facilitated directional fast transport and efficient desorption of droplets, thus improving water collection efficiency. The enhancement mechanism of the water harvesting behavior for such surfaces was analyzed, with one focus on enhancing collection in hydrophobic regions with capillaries to reduce bouncing off loss and the other on improving balanced cycling of the collection process. At a fog flow rate of 1500ml/h and 20cm away from the fog outlet, the directional leaf vein-patterned 19.625cm2 sized surface demonstrated a fog water collection rate (WCR) of 5.6 Kg·m-2·h-1 and first drop collection at the 49th s, an impressively short time rarely reported. Compared to the superhydrophobic, superhydrophilic samples, and the reference, WCR increased by 180%, 62%, and 59%, respectively, and the first droplet collection time decreased by 73%, 46%, and 62%, respectively. This efficient water collection method has huge potential in arid regions.

Dual Biomimetic Synergistic Effects of Cactus Spines and Desert Beetle Shells for Water-In-Oil Emulsion Separation.

Drawing inspiration from the unique properties of cactus spines and desert beetle shells, we have designed a biomimetic stainless steel mesh specifically for efficient water-in-oil emulsion separation. The tapered arrays of cactus spines are prepared by a light-curing-templating method, and the hydrophobic regions are constructed by adhering hydrophobic silica nanoparticles to the surface of the mesh. This innovative design takes full advantage of the unique properties of these two natural plants, which can agglomerate tiny emulsified water to achieve an emulsion-breaking effect only under static conditions. At the same time, the stainless steel mesh with the conical arrays has a high water-in-oil emulsion separation efficiency (up to 99.6%), high permeance (2400 L·m-2·h-1·bar-1), and good cycling performance. The concept of dual biomimetic explored in this work may extend beyond oil-water separation to encompass various applications, such as fog collection, droplet manipulation, and more.

Biomimetic multi-functional 3D fog collector: Independent of fog flow direction

The shortage of freshwater resources has a great impact on the daily life of human beings, and fog collection has become an effective mitigation measure. In this paper, inspired by the nanofabricated desert beetle, honeycomb, Euphorbia antiquorum L. and cactus, a 3D fog collector combining a conical array structural gradient and a wettability gradient was presented, with special three-dimensional array structure (TA-L/B (PPC)) that ensures that the fog-collecting efficiency of the samples is virtually independent of the direction of the fog flow. The fog collection efficiency of sample TA-L/B (PPC) is close to 4.3 g·h−1·cm−2, a value that is 1.77 times higher than the surface fog collection efficiency of the copper sheet (OS) sample. By rationally designing the surface structure of the sample, the fog circulation process is accelerated, and a sustainable and stable fog collection process is achieved.

Fog collection on wettability-mixed patterned surfaces inspired by multiple biological structures

Fog collection has become one of the effective means to solving water scarcity. Wettability-mixed patterned surfaces exhibit great potential in fog collection. In this article, the desert beetle, honeycomb structures and cactus spines served as an inspiration in the proposal of a bionic pattern of honeycomb and cactus spine coupling (BPHCSC) that can efficiently collect fog. First, a superhydrophobic (SHB) surface was successfully prepared on the surface of 5052 Al alloy through combined electrochemical etching with fluorosilane modification. Subsequently, laser etching technology was used in the precise etching of a superhydrophilic BPHCSC on the SHB surface. Compared with the fog collection efficiencies of a single SHB surface and the honeycomb-like wettability-mixed patterned surface composed of rectangular channels, that of the prepared BPHCSC surface increased by approximately 23.5% and 4.27%, respectively. In addition, a thorough exploration was conducted on the effects of factors, such as the distance between the sample surface and the fog outlet, tilt angle and the number of laser etchings, on fog collection efficiency. This study provides a new idea for fog collection and exhibits a broad application potential in fields, such as microfluidic systems, droplet manipulation and cell screening.

Biomimetic Fog Collector with Hybrid and Gradient Wettabilities.

Water scarcity is a global problem and collecting water from the air is a viable solution to this crisis. Inspired by Namib Desert beetle, leaf venation and spider silk, we designed an integrated biomimetic system with hybrid wettability and wettability gradient. The hybrid hydrophilic-hydrophobic wettability design that bionomics desert beetle's back can construct a three-dimensional topography with a water layer on the surface, expanding the contact area with the fog flow and thus improving the droplet trapping efficiency. The venation-like structure with wettability gradient not only provides a planned path for water transportation, but also accelerates water removal under the synergistic effect of gravity and wettability driving force, thus further improving the surface regeneration rate. The collector combines droplet capture, coalescence, transportation, separation, and storage capabilities, which provides new ideas for the design of future high-efficiency fog collectors.

Multibioinspired Hybrid Superwetting Surface for Efficient Fog Collection and Power Generation.

Obtaining water and renewable energy from the atmosphere provides a potential solution to the growing energy shortage. Leveraging the synergistic inspiration from desert beetles, cactus spines, and rice leaves, here, a multibioinspired hybrid wetting rod (HWR) is prepared through simple solution immersion and laser etching, which endows an efficient water collection from the atmosphere. Importantly, benefiting from the bionic asymmetric pattern design and the three-dimensional structure, the HWR possesses an omnidirectional fog collection with a rate of up to 23 g cm-2 h-1. We further show that the HWR could be combined with a droplet-based electricity generator to convert kinetic energy from falling droplets into electrical energy with a maximum output voltage of 200 V and a current of 2.47 μA to light up 28 LEDs. Collectively, this research provides a strategy for synchronous fog collection and power generation, which is promising for environmentally friendly energy production.

Biomimetic Leaf-Shaped Wedge Structure with Mixed Wettability for Fog Harvesting.

Water scarcity is a pressing issue in arid and semi-arid regions, making fog harvesting a promising method for water collection. However, enhancing the rate of fog harvesting remains a challenge. Controlling the movement of droplets on functional surfaces is crucial for the development of effective water-harvesting devices. In this study, a three-dimensional (3D) fog-harvesting device with mixed wettability is fabricated using a combination of physical and chemical techniques. With inspiration drawn from natural organisms, such as the desert beetle and Nephrolepis cordifolia, which can both live in low humidity, a copper substrate with a leaf-shaped wedge superhydrophilic structure and flat superhydrophobic regions is fabricated for fog harvesting. The modified surface results in a maximum 49.89% improvement in fog-harvesting efficiency compared to the original copper substrate. The synergistic effect of the 3D structure and mixed wettability of this study offers an idea for improving fog collection efficiency, with potential implications for energy sustainability water resources.

Bioinspired superwettable electrode towards sensitive detection of myocardial infarction-specific miRNA

The development of a reliable and sensitive method for the detection of myocardial infarction (MI)-specific miRNAs is of great significance in the diagnosis and management of MI. Electrochemical biosensors have emerged as a promising tool for the detection of biomolecules due to their high sensitivity, selectivity, simplicity of operation, and miniaturization. In order to further improve the sensitivity and selectivity of DNA electrochemical biosensors and meet the requirements of microRNA detection in biological samples, we fabricated a patterned superwettable gold electrode (PS-Au electrode) by mimicking the superwettable micropatterns of the desert beetle. Combining this bioinspired electrode with a DSN-assisted target recycling amplification strategy, we achieved ultrasensitive detection of myocardial infarction-specific miRNA-483 ranging from 10 aM to 100 fM with a low detection limit of 5.32 aM for miRNA-483. The electrochemical biosensor based on PS-Au electrode and DSN-assisted target recycling amplification (PSE-DTRA-EB) has good stability and specificity. Our study provides a new method for the ultrasensitive detection of MI-specific miRNAs, which may have important clinical applications in the diagnosis and prognosis of MI.

In Situ Collection and SERS Detection of Nitrite in Exhalations on Facemasks Based on Wettability Differences.

As one of the common carriers of biological information, along with human urine specimens and blood, exhaled breath condensate (EBC) carries reliable and rich information about the body's metabolism to track human physiological normal/abnormal states and environmental exposures. What is more, EBC has gained extensive attention because of the convenient and nondestructive sampling. Facemasks, which act as a physical filter barrier between human exhaled breath and inhaled substances from the external environment, are safe, noninvasive, and economic devices for direct sampling of human exhaled breath and inhaled substances. Inspired by the ability of fog collection of Namib desert beetle, a strategy for in situ collecting and detecting EBC with surface-enhanced Raman scattering is illustrated. Based on the intrinsic and unique wettability differences between the squares and the surrounding area of the pattern on facemasks, the hydrophilic squares can capture exhaled droplets and spontaneously enrich the analytes and silver nanocubes (AgNCs), resulting in good repeatability in situ detection. Using R6G as the probe molecule, the minimal detectable concentration can reach as low as 10-16 M, and the relative standard deviation is less than 7%. This proves that this strategy can achieve high detection sensitivity and high detection repeatability. Meanwhile, this strategy is applicable for portable nitrite analysis in EBC and may provide an inspiration for monitoring other biomarkers in EBC.

Droplet Bottom Expansion and Its Wettability Control Mechanism Based on Macroscopic Defects.

Biomimetic surfaces with special wettability have received much attention due to their promising prospects in droplet manipulation. Although some progress has been made, the manipulation of droplets by macroscopic defects of the millimeter structure and the wetting-state transition mechanism have rarely been reported. Herein, inspired by lotus leaves and desert beetles, biomimetic surfaces with macroscopic defects are prepared by laser processing and chemical modification. Various functions of droplet manipulation are achieved by controlling the millimeter-scale macroscopic defects, such as droplet capture, motion trajectory changing, and liquid well. And a droplet bottom expansion phenomenon is proposed: wetting-state transition in superhydrophobic regions around defects. The "edge failure effect" is proposed to explain the force analysis of droplet capture and the droplet bottom expansion to distinguish it from the adhesion phenomenon presented by the droplet sliding. 53.28° is defined as the expanded saturated angle of the as-prepared surface, which is used to distinguish whether the defect could cause the droplet bottom expansion. An enhanced edge failure effect experiment is designed to make the droplet bottom expansion more intuitive. This work provides a mechanistic explanation of the surfaces that utilize macroscopic defects for droplet manipulation. It can be applied to the monitoring of droplet storage limits, providing a perspective on the design and optimization of superhydrophobic surfaces with droplet manipulation.

Beetle-inspired AuNPs semi-embedded colloidal crystal chips for the highly sensitive and colored detection of chloramphenicol in foods

Inspired by the desert beetle, a novel biomimetic chip was developed to detect chloramphenicol (CP). The chip was characterized by a periodic array in which hydrophobic Au nanoparticles (AuNPs) were semi-embedded on hydrophilic polymethyl methacrylate (PMMA) spheres. Among them, the AuNPs exhibited both a localized surface plasmon resonance effect to amplify the reflected signal and a synergistic effect with PMMA spheres to create a significant hydrophilic-hydrophobic interface, which facilitated the enrichment of target CP molecules and improved sensitivity. After optimization, the chip showed direct, ultrasensitive (as low as 0.2 ng/mL), fast (5 min), and selective detection of CP with a wide concentration range extending from 0.2 ng/mL to 1000 ng/mL. During detection, color changes of the chip were observed by naked eyes without any color display equipment. The recovery of CP was between 94.65 % and 108.70 % in chicken and milk samples.

Improved Fog Collection on a Hybrid Surface with Acylated Cellulose Coating.

Fog collection serves as an efficient method to alleviate water scarcity in foggy, water-stressed regions. Recent research has focused on constructing a hybrid surface to enhance fog collection efficiency, with one approach being the prevention of liquid film formation at hydrophilic sites. Inspired by the desert beetle, a coating (10-MCC) made by partially acylating microcrystalline cellulose (MCC) exhibits hydrophilic sites alongside a hydrophobic skeleton enabling rapid droplet capture despite its overall hydrophobicity. The captured droplets quickly coalesce into a large droplet driven by the wetting gradient created by the hydrophobic backbone and hydrophilic sites. To achieve greater fog collection efficiency, a hydrophobic-superhydrophobic hybrid surface is formed by combining a coating of 10-MCC with a superhydrophobic surface. The construction of superhydrophobic surfaces typically involves creating a rough surface with a distinctive structure produced by the anodization technique and modifying it with stearic acid. The superhydrophobic surface exhibits excellent corrosion resistance and mechanical stability. Moreover, the hybrid surface shows high efficiency in fog collection, with a tested maximum efficiency of approximately 1.5092 g/cm2/h, 1.77 times that of the original Al sheets. The results demonstrate a remarkable enhancement in fog collection capacity. Furthermore, this work serves as an inspiration for the low-cost and innovative design of engineered surfaces for efficient fog collection.

Patterned Quasi‐Liquid Surfaces for Condensation of Low Surface Tension Fluids

AbstractExtensive research concerns dropwise condensation of low surface tension fluids to promote energy efficiency and decarbonization in thermal energy systems. However, it is challenging as these fluids typically result in filmwise condensation. Drawing inspiration from the Namib desert beetle that enhances condensation through patterned wettability, conventional beetle‐inspired surfaces excel in water condensation but flood when condensing low surface tension fluids. In this work, a patterned quasi‐liquid surface is reported that achieves exceptional dropwise condensation of low surface tension fluids. The surface consists of alternating stripes with low surface energy, that is, a perfluoropolyether (PFPE) and fluorinated quasi‐liquid surface (FQLS), that shows ultralow contact angle hysteresis for ethanol and hexane. The PFPE stripes are slightly more slippery, acting as slippery bridges that accelerate droplet coalescence and removal. It is experimentally demonstrated that the striped PFPE‐FQLS pattern exhibits a heat transfer coefficient 85%, 330%, and 550% higher than that of PFPE, fluorinated silane, and filmwise condensation, respectively. This study reveals that a high contact angle is desired to sustain dropwise condensation, irrespective of contact angle hysteresis. These findings provide a new paradigm for promoting the dropwise condensation of low surface tension fluids and offer valuable insights into surface design for energy sustainability.

Enhancing gas film stability by alternating superhydrophobic and hydrophobic surfaces for stable drag reduction

Superhydrophobic surfaces can significantly reduce the resistance of underwater vehicles, but as the speed increases, the gas film is prone to be destroyed, leading to a decrease in the drag reduction effect or even an increase in the drag. Therefore, enhancing the stability of the gas film is crucial for maintaining the drag reduction effect. Inspired by the honeycomb array pit structures, the high adhesion hydrophobic properties of rose petals, and the wetting gradient surface of Namib desert beetles, an alternating superhydrophobic and hydrophobic surface (ASHHs) was constructed by femtosecond laser to enhance the stability of the gas film. The high adhesion hydrophobic surface (HAHs) provides greater adhesive force, allowing the gas film to firmly pin at the junction of a low-adhesion superhydrophobic surface (LASHs) and HAHs, thereby enhancing the stability of the gas film. The critical failure velocity of ASHHs can reach 2.3 m/s, which is significantly greater than that of low-adhesion superhydrophobic surface samples (LASH-S) (1.7 m/s). ASHHs maintains a stable drag reduction effect of 37% at a velocity of 2.3 m/s, while that of LASH-S is only 6%. It is envisioned that such superhydrophobic surfaces that enhance gas film stability should find widespread applications in minimizing resistance and reducing energy consumption in the marine engineering field.

Bioinspired 1T-MoS2-based aerogel beads for efficient freshwater harvesting in harsh environments

Freshwater scarcity is one of the most critical issues worldwide, particularly in arid regions, stemming from population growth and climate change. Inspired by the hydrophilic bump structures of desert beetles, 1T-MoS2-based aerogel beads with porous structures and CaCl2-crystal loading (termed as MoAB-m@CaCl2-n) were prepared for freshwater harvesting. Metallic-phase MoS2 nanospheres exhibit excellent photothermal conversion abilities, facilitating solar-driven water desorption and evaporation. Owing to the synergistic effect of its localized surface features, hydrophilic groups, and dispersive CaCl2 particles, MoAB-2@CaCl2-2 efficiently harvests water from atmosphere with a superior moisture adsorption capacity (0.18–0.82 g g−1) at a wide range of relative humidity (10 %-70 %). Under one-sun illumination, MoAB-2@CaCl2-2 demonstrates an outstanding solar-driven water evaporation rate of 2.25 kg m-2h−1. The water evaporation rate from soil (water content = 20 %) is 1.19 kg m-2h−1, which is sufficient for sustainable freshwater generation from the soil in arid regions. More importantly, the multifunctional MoAB-2@CaCl2-2-based homemade freshwater generation prototype delivers a certain amount of water harvesting (0.99 g g−1 day−1) on a rainy day and provides an impressive daily freshwater yield (53.7 kg m−2) under natural sunlight. The integrated device exhibits excellent efficiency and practicality and offers a feasible method for freshwater harvesting in harsh environments.

Fog harvesting efficiency analysis of biomimicking surfaces: A review

With a rapidly increasing population, pollution levels and industrial water and energy demand are on a constant rise in the past century. Populations residing in arid and semi-arid regions have been victims of water shortage issues since decades. Efficient water harvesting techniques are becoming highly significant today for ensuring the availability of essential resources throughout the globe. Inspired from nature where certain creatures have attractive surfaces which can collect water from the fog or mist even in no rainfall conditions, researchers have developed high-efficient novel water harvesting materials that could effectively address water scarcity issues. Through an in-depth analysis of the wettability and water droplet transportation of these creatures in nature, novel bionic surfaces that combine desirable natures and properties have been developed through innovative fabrication and coupling techniques. This could achieve 2.5 to 5.3 times more efficient water harvesting than conventional superhydrophobic and superhydrophilic surfaces. The efficiency value increased by 250% to 600% by merging different morphologies like Desert beetle, cactus and Janus, compared to their individual uniform morphology surfaces. The review also presents current challenges and scope for future development in water harvesting materials.