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Inspired by Namib Desert beetle and leaf venation, a wettability-integrated system consisting of wettability-hybrid coatings and venation-like patterns was designed and successfully fabricated via a simple, low-cost, and eco-friendly route. The as-prepared surface can construct a 3D topography with a water layer and efficiently drain through the venation-like patterns. The combination of multiple mechanisms enhances the fog harvesting ability significantly. Meanwhile, the synergistic mechanisms of fog harvesting enhancement by a wettability-integrated surface were further studied and discussed.

This paper reviews the polysaccharide-based aerogels reported in recent years for oil–water separation, compares their efficiency in the oil–water separation process, and provides ideas for the preparation of green oil–water separation materials.

A novel fabrication of TiN/CNTs@CC was presented and can be used as electrodes with good flexibility and conductivity in ZIHCs.

The fabric not only has good electrical conductivity, chemical stability and mechanical durability, but also exhibits excellent electrothermal effects and de-icing properties. In addition, it can be used to monitor various movements of the human body.

The electrical conductivity of SLIPS-A has a negative correlation with the increasing corrosion resistance.

Here, a magnetic responsive composite surface (MRCS) was prepared by injecting a magnetic elastomer into ZnO nanoarrays for intelligent control of droplet/bubble transport. This non-pollution, non-contact operation method has shown great potential in micro-fluids, micro-chemical reactors, chip laboratory environments and other related applications.

It is difficult for traditional droplet manipulation to combine transportation and rapid capture of droplets on an inclined surface. In this work, a slippery magnetic track (SMT) is presented to manipulate droplets and bubbles in a magnetic field. By changing the direction of the magnetic field, the transitions from non-pinning to pinning states on the SMT can be achieved. Through the SMT surface, it is possible to capture and release droplets and bubbles in the vertical direction. The detailed theoretical and experimental studies of droplet and bubble manipulation are discussed. This work demonstrates the versatility of magnetic manipulation, including the transition of droplet trajectory and bubble removal, which will facilitate the research of intelligent interfaces in energy transmission, drug transport and micro engineering.

Here, we adopted a simple method to prepare an integrated mesh with an anisotropic surface (IMAS). The motion mode of the droplet can be switched by changing the tilt angle of the IMAS. This low-cost and convenient operation method has great application potential in biomimetic functional surface preparation, microfluidics

Functional superamphiphobic fabrics have attracted considerable attention for applications thanks to their anti-contamination and increased-buoyancy features.

Cellulose paper derived from plants is used for daily writing and recording, and has historically played an important role in promoting cultural dissemination and inheritance. However, it attracted more and more attentions in recent years serving as a flexible platform or substrate for application in environment and energy, attributing from its many inherent advantages such as biocompatibility, biodegradability, sustainability, low cost, and great capability to be modified. With the development of various industries, especially the flexible electronics industry, the demand for two-dimensional (2D) paper-like materials has increased. Several kinds of inorganic paper are manufactured and have been widely used in many fields. Among them, there are hydroxyapatite (HAP)-based and carbon-based inorganic paper that give play to their own advantages and have been well applied in some fields. In addition, there are many composite papers, which are assembled from several raw materials (cellulose fibers, HAP, carbon), exhibiting excellent characteristics. Cellulose paper is no longer limited to traditional writing applications, but has great potential to be used in many aspects, achieving a gorgeous change in its role. The emergence of inorganic paper and hybrid paper has further demonstrated the application prospects of paper-like two-dimensional materials. This paper will start from the characteristics of the three types of paper and composite paper, and summarize their typical applications in the environment and energy fields.

A smart separation membrane with super-amphiphilic wettability was fabricated by a simple two-step method. The separation efficiency of the membrane towards the emulsion is more than 99.6%, and it can be recycled.

Mechanically and thermally stable hydrophobic aerogels were prepared by simple boric acid condensation, freeze-drying, and chemical vapor deposition for the treatment of oily wastewater.

A simple preparation of a F-TiO2-HNT superamphiphobic surface with a tube-point-like micro/nano hierarchical structure. The self-cleaning principle and hydrophobic mechanism of the surface were analyzed.

The harsh working environment affects the performance and usage life of Al and its alloys, thus limiting their application. In recent years, Slippery Liquid-infused Porous Surface (SLIPS) has attracted much attention due to excellent anti-corrosion, anti-fouling and anti-icing properties. This may be an effective way to improve the properties of Al and its alloys. Here, the SLIPS with petal-like structure was constructed on the Al alloy via simple hydrothermal reaction, Stearic Acid (STA) modification and lubricant injection. A variety of droplets (including oil-in-water emulsions) can slide on the SLIPS at a low angle, even the Sliding Angle (SA) of the water droplet is only 3°. Furthermore, the SLIPS exhibits outstanding mechanical and chemical properties. It can maintain fine oil-locking ability under high shearing force and keep slippery stability after immersion in acid/alkaline solutions. In addition, the SLIPS possesses excellent anti-corrosion, anti-fouling and anti-icing properties, which provides a new way to promote the application of Al and its alloys. Therefore, the SLIPS is expected to be an effective way to improve the properties of Al and its alloys, as well as play a role in anti-fouling and self-cleaning in construction, shipbuilding and automotive manufacturing industries, thereby expanding the practical application of Al and its alloys.

Hypothesis The droplet manipulation behavior is affected by chemical structural driving force (including the superposition of electric, magnetic, optical and thermal fields), which directly determine transportation velocity. A lot of research has focused on a single driving force that induces the directional transportation behavior, which affects its performance. Experiments A simple method for preparing wettability gradient conical copper needles (WGCCN) combining structural gradient and chemical gradient was formulated. The effect of droplet volume and tilt angles on droplet transport velocity was systematically studied. The process of droplet transport was revealed through theoretical model and mechanical analysis. Finally, the application of WGCCN and its array model in fog collection were explored. Findings A continuous chemical gradient in the conical structure gradient induces the droplet directional transportation, and the transportation velocity depends on the droplet volume. In addition, under the cooperation effect of multiple driving force, the droplet can still be transported in a directional orientation even if it is tilted at a certain angle. The simple droplet manipulation behavior portends that the droplets directional transport behavior can be applied in microfluidic manipulation by cooperation of effective multiple driving force with satisfactory results.

There have been many studies on special wetting surfaces, but most of them just stay superlyophobic in air or underwater. In this work, a membrane with photoresponse is fabricated by spraying hybrid particles of silicon and titanium dioxide. Under the combined action of hybrid particles and 1H,1H,2H,2H-perfluorodecyltrimethoxysilane, the prepared membrane is superhydrophobic in air. Because of the presence of titanium dioxide, the membrane can realize the transformation from superoleophilic underwater to superoleophobic underwater through UV irradiation and heating. Surprisingly, the membranes with superoleophobicity underwater are also superhydrophobic underoil. Thanks to this unique wettability transition, the prepared membrane can be applied to emulsion separation and fog harvesting. This is inspiring for the preparation and the multifunctional application of multiphase media superlyophobic surfaces.

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.

Problems such as increasingly serious water pollution attracted widespread concern. The underwater OCAs of the samples became larger with increasing pH and the under-oil WCAs of the samples did not vary regularly with increasing pH. Nanoneedle structures were grown on metal foam by anodization. Cellulose is fixed to the frame by cross-linking with supramolecular binder poly(vinyl alcohol)/tannin. A cellulose/poly(vinyl alcohol)/tannin porous composite framework with special wettability is prepared. This porous composite framework can be used for the continuous separation of oil/water mixtures with high separation efficiency, high throughput, excellent reusability, and mechanical durability. In addition, due to the coating of cellulose and the supramolecular binder, the pore size of the frame is reduced, and the cagelike structure of the porous framework can promote its demulsification effect. Therefore, the cellulose/poly(vinyl alcohol)/tannic acid porous composite frame can also be used for the separation of oil/water emulsions. This porous frame material has broad application prospects in oil spill treatment and sewage purification.

Polydopamine as a multifunctional biomimetic polymer with nonselective strong adhesion properties has become a hot research topic in recent years. However, there are a few reports on the durable and effective emulsion separation of polydopamine composites from other materials. Therefore, it is necessary to construct durable polydopamine composites to achieve selective adsorption of materials. In this work, polypyrrole (PPy)-PDA was obtained on sponges by an in situ polymerization reaction, followed by the attachment of SiO

Biomimetic 3D hydrophilic-superhydrophobic hybrid surfaces with bump structures were prepared by a combination of spin-coating and high-temperature calcination. How wettability and different bulge morphologies affect droplet capture and removal behavior were compared and analyzed. Hydrophilic-superhydrophobic hybrid PDMS@copper with linear bumps showed the best water-collecting performance, bettering by 151% the original copper sheet and showing a 135% improvement over a superhydrophobic surface without bulges. Both hemispherical and linear bulges accelerate droplet nucleation and growth, but the unique anisotropy of linear bulges enhances the water collection performance of samples with linear bulges. This combination of hybrid wettability and surface morphology inspires 3D structured surfaces and hybrid wettability surfaces.

Small-scale robots (SSRs) have emerged as promising and versatile tools in various biomedical, sensing, decontamination, and manipulation applications, as they are uniquely capable of performing tasks at small length scales. With the miniaturization of robots from the macroscale to millimeter-, micrometer-, and nanometer-scales, the viscous and surface forces, namely adhesive forces and surface tension have become dominant. These forces significantly impact motion efficiency. Surface engineering of robots with both hydrophilic and hydrophobic functionalization presents a brand-new pathway to overcome motion resistance and enhance the ability to target and regulate robots for various tasks. This review focuses on the current progress and future perspectives of SSRs with hydrophilic and hydrophobic modifications (including both tethered and untethered robots). The study emphasizes the distinct advantages of SSRs, such as improved maneuverability and reduced drag forces, and outlines their potential applications. With continued innovation, rational surface engineering is expected to endow SSRs with exceptional mobility and functionality, which can broaden their applications, enhance their penetration depth, reduce surface fouling, and inhibit bacterial adhesion. This article is protected by copyright. All rights reserved.

Graphic abstract Based on aphid wax–honeydew marble and the hydrophobic wax structure of lotus and its derived applications with superareophilic and superhydrophobic properties, edible carnauba wax and beeswax particles were mixed and utilized to mimic lotus wax and wrap liquid, thus forming liquid marbles (LMs). Through the utilization of continuous production system (CPS), wax as an interfacial surfactant, water and solid, air-phase or mixed-phase marble content was produced. The edible liquid marble (ELM) could encapsulate water and food droplets. Edible solid marble (ESM) and edible solid hollow marbles (ESHMs) could be fabricated by applying pectin or syrup. Moreover, through the heating of wax powders with different melting temperatures, stable tablets and hollow capsules could be produced. The wax powder as interfacial surfactant could firmly bind with pectin through hydrogen bonds on ESM. The edible LMs can therefore be applied for residue reduction, corrosion reduction, biohazard prevention and cleaning in the food industry. The other phase LMs could act as novel tools in the pharmaceutical and food industries with the above-mentioned water transport, preservation, sustained releasing and selective releasing abilities. Supplementary Information The online version contains supplementary material available at 10.1007/s42242-021-00158-z.

Inspired by Nepenthes pitcher plants, slippery liquid-infused porous surfaces (SLIPSs) have attracted wide attention and exhibited remarkable liquid repellency, droplet motion control and antifouling properties. However, lubricant-impregnated surfaces have poor durability, leading to loss of control of the movements of droplets during applications. Herein, WO3-based slippery coatings with high stability were prepared by the spray method and photocatalytic reaction. Notably, on the basis of the hierarchical structures, the strong intermolecular forces between the polydimethylsiloxane brush and silicone oil led to the formation of a stable lubricant layer on the WO3-based slippery coating, which can suppress lubricant loss during water collection. After a series of stability tests, such as high-speed centrifugation, long-term storage, acidic solution and multiple heating/cooling cycles, the biomimetic slippery surface still displays excellent surface-slippery stability. Furthermore, the slippery surface exhibits superior water mist capture, water droplet expansion and harvested water removal abilities, leading to good water collection performance. The silicone oil content in the collected water was 28 mg/L, demonstrating that the loss of oil was lower during the water collection process. Even under harsh environments, including multiple heating/cooling cycles, long-term storage and high shear force, lubricant-impregnated coatings can also maintain good water collection efficiency. Therefore, these slippery coatings are promising for widespread application.

The performance degradation of oil caused by moisture and water pollution induced by the infiltration of oil can result in huge losses for society. This is especially true of stable emulsified mixtures of oil and water, which are difficult to separate and urgently require a processing method. In this work, a robust Janus membrane prepared by combining simple electrodeposition and spraying processes was used to separate water-in-transformer oil/lubricating oil emulsions and various oil-in-water emulsions. The membrane with outstanding separation efficiency was also endowed high flux to emulsions, even after 10 separation cycles and 100 sand impact tests, indicating that separation ability was retained. Furthermore, the excellent resistance to acidic and alkaline liquids of the superhydrophobic side groups of the membrane increased the possibility of its service in harsh environments. This study's findings reveal great potential regarding the expansion and application of oil-water separation materials.

There has never been a dose-response meta-analysis of the relationship between physical activity and the risk of depression. Hence, we aimed to explore the dose-response relationship between leisure-time physical activity (LTPA) and the risk of depression through a meta-analysis to provide a basis for the prevention of depression.PubMed and Web of Science databases were searched using a computer to collect prospective cohort studies on the relationship between LTPA and depression between January 1997 and July 2021. A dose-response meta-analysis was performed using the Stata 14 software to calculate the combined effect size relative risk (RR and 95% confidence interval CI).Twelve cohort studies included 310,359 subjects who met the inclusion criteria. The categorical dose-response analysis results showed that the risk of incident depression was 27%, 17%, and 8% lower for the light, moderate, and highest dose LTPA participants, respectively (RR: 0.73, 95% CI: 0.64-0.82; RR: 0.83, 95% CI: 0.78-0.87; RR: 0.92, 95% CI: 0.86-0.99), compared with the lowest LTPA category. Continuous dose-response analysis showed a nonlinear relationship between LTPA and the risk of incident depression (P = .04). The risk of incident depression was reduced by 3% (RR: 0.97, 95% CI: 0.95-0.98) for every 5 MET-h/week increase in LTPA 25 MET-h/week; when LTPA was higher than 25 MET-h/week, a 4% increase in the risk of depression for every 5 MET-h/week increase was observed (RR: 1.04, 95% CI: 1.02-1.05).There was a nonlinear relationship between LTPA and the risk of incident depression. Moderate and low doses of LTPA were protective factors in preventing the risk of incident depression, while high doses of LTPA may increase the risk of incident depression.

In recent years, the rapid development of microfluidic technology has caused a revolutionary impact in the fields of chemistry, medicine, and life sciences. Also, droplet control is one of the most important technologies in the field of microfluidics. In order to achieve different degrees of droplet transport, the dynamic balance of the competing processes of droplet driving force and fluid resistance should be controlled to achieve good selectivity of droplet transport. Here, we focus on the principles of droplet transport in microfluidic devices, including the driving forces for droplet transport in fluids and the effects of transport properties on droplet transport. After that, the effects of external fields on the directional transport of droplets and the advantages and disadvantages of each external field in droplet transport are discussed in detail. Finally, the applications and challenges of droplet microfluidics in chemical, biomedical, and mechanical systems are comprehensively introduced.

Superhydrophobic conductive materials have gained more attention due to their broad applications in oil-water separation, electromagnetic shielding, and wearable heaters. With their inherent softness and breathability, fabrics are an excellent choice for wearable heater substrates. In this work, we decorate MXene(Ti

The slippery liquid-infused porous surface(s) (SLIPS) that imitates the Nepenthes pitcher plant has proven to be highly versatile and can be combined with various surface characteristics such as dynamic response, antifouling, selective adhesion, and optical/mechanical tunability. In addition, the introduction of a lubricating fluid layer also gives it extremely low contact angle hysteresis and self-repairing properties, which further expands its application range. Currently, SLIPS has been proven to be suitable for many frontier fields such as aerospace, communications, biomedicine, and microfluidic manipulation. In this review, we explain the theoretical background of SLIPS and the preparation methods currently available, including the choice of substrate materials and lubricants, and we discuss the design parameters of the liquid injection surface and how to deal with the consumption of lubricants in practical applications. In addition, the paper focuses on current and potential applications, such as preventing pathogen contamination of and blood adhesion of medical equipment, manipulation of tiny droplets, and directional transportation of liquids. Finally, some weaknesses that appear when SLIPS is used in these applications are pointed out, which provides a new perspective for the development of SLIPS in the future.

With the explosive growth of the world’s population and the rapid increase in industrial water consumption, the world’s water supply has fallen into crisis. The shortage of fresh water resources has become a global problem, especially in arid regions. In nature, many organisms can collect water from foggy water under harsh conditions, which provides us with inspiration for the development of new functional fog harvesting materials. A large number of bionic special wettable synthetic surfaces are synthesized for water mist collection. In this review, we introduce some water collection phenomena in nature, outline the basic theories of biological water harvesting, and summarize six mechanisms of biological water collection: increased surface wettability, increased water transmission area, long-distance water delivery, water accumulation and storage, condensation promotion, and gravity-driven. Then, the water collection mechanisms of three typical organisms and their synthesis are discussed. And their function, water collection efficiency, new developments in their biomimetic materials are narrated, which are cactus, spider and desert beetles. The study of multiple bionics was inspired by the discovery of Nepenthes’ moist and smooth peristome. The excellent characteristics of a variety of biological water collection structures, combined with each other, are far superior to other single synthetic surfaces. Furthermore, the main problems in the preparation and application of biomimetic fog harvesting materials and the future development trend of materials fog harvesting are prospected.

Droplet manipulation plays an important role in scientific research, daily life, and practical production such as biological and chemical analysis. Inspired by the structure and function of three typical leaf veins, the bionic texture was replicated by the template method, and the artificial leaf was selectively treated by nanoparticles to obtain a quasi-three-dimensional hybrid superhydrophobic-hydrophilic surface. When the droplet touches the surface of the leaf, it will be attracted to the bottom of the main vein from different directions even in horizontal conditions due to the Laplace pressure gradient and energy gradient. The simulation analysis demonstrates that the reason for directional transportation is the energy gradient of the droplets on the different levels of veins, including the thin veins, lateral veins, and main vein. Meanwhile, the experimental result of water collection also showed an outstanding directional transportation effect and excellent water collection efficiency. In addition, when the sample is tilted upside down, the droplet will flow back to the main vein along the lateral vein and then flow down the main vein, showing a good droplet pumping effect. Therefore, the directional and polydirectional transportation of droplets on the same sample is successfully realized, and the conversion between executing single and multiple tasks simultaneously can be realized only by upright and inverted samples. This work provided a new strategy for directional and polydirectional water manipulation, water collection, directional drainage, and microfluidic devices.