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Microfluidics and bioinspired superwetting materials, as two crucial branches of scientific research, are entering their golden age of development. As an emerging interdisciplinary subject of these two fields, bioinspired superwetting open microfluidics is triggering technological revolutions in many disciplines, including rapid medical diagnosis, biochemical analysis, liquid manipulation, 3D printing, etc. However, this new research area has yet to attract extensive attention. So, a timely review is necessary to organize the development process, summarize current achievements, and discuss the challenges or chances for the ongoing scientific trend. In this review, the evolution from closed to open microfluidics is combed first. Then, three typical bioinspired superwetting systems are introduced emphatically. Based on this, the bioinspired superwetting open microfluidics is divided into different categories according to the bionic objects as the focus of this study. Taking natural phenomena as the entry point, the research from the underlying mechanism to the application is systematically discussed and summarized. Several emerging applications are also mentioned. Finally, some views on major problems, existing challenges, and developing trends are briefly put forward in this field to guide future research. [ABSTRACT FROM AUTHOR]

Highlights: Engineering MXene into electrospun nanofibers can effectively enhance its thermal emissivity and conductance, and the unidirectional water transport of the wettability-gradient-induced-diode (WGID) membrane displayed diode-like properties with wettability gradient by tailoring the water contact angle of each single layer. The WGID membrane could achieve a cooling temperature of 1.5 °C in the "dry" state, and 7.1 °C in the "wet" state, with high emissivity of 96.40% in the MIR range, superior thermal conductivity of 0.3349 W m−1 K−1. Zero-energy-consumption for personal cooling management via multiple heat dissipation pathways, including thermal radiation, conduction, and evaporation. Thermoregulatory textiles, leveraging high-emissivity structural materials, have arisen as a promising candidate for personal cooling management; however, their advancement has been hindered by the underperformed water moisture transportation capacity, which impacts on their thermophysiological comfort. Herein, we designed a wettability-gradient-induced-diode (WGID) membrane achieving by MXene-engineered electrospun technology, which could facilitate heat dissipation and moisture-wicking transportation. As a result, the obtained WGID membrane could obtain a cooling temperature of 1.5 °C in the "dry" state, and 7.1 °C in the "wet" state, which was ascribed to its high emissivity of 96.40% in the MIR range, superior thermal conductivity of 0.3349 W m−1 K−1 (based on radiation- and conduction-controlled mechanisms), and unidirectional moisture transportation property. The proposed design offers an approach for meticulously engineering electrospun membranes with enhanced heat dissipation and moisture transportation, thereby paving the way for developing more efficient and comfortable thermoregulatory textiles in a high-humidity microenvironment. [ABSTRACT FROM AUTHOR]

Wetting and spreading are familiar phenomena in nature and commonly observed in our daily life, and of great significance for basic scientific researches as well as providing solutions to the cutting-edge technical applications. Recent decades, learning from Nature, unique wetting and spreading behaviors have been bio-mimetically realized through the construction of artificial materials, which have promoted the ongoing development of relating areas like the liquid transportation, spraying, cleaning, and painting in industry and agriculture, and even influenced the way of our daily life. A systemic and timely review is therefore necessary to summary the existing novel researches and provide some idea of the next tide in leading the scientific trend. Here, we will present how the bio-inspired materials with special wettabilities have been integrated into traditional materials or devices to improve their wetting and spreading performances. The progresses of both fundamental theories and cutting-edge applications that reported in recent years are briefly reviewed. Basing on the impacting state of the liquid, the wetting and spreading progresses have been divided into 3 categories: which include interaction between the solid surfaces with the static contacting drop, dynamic impacting drop, and overflowing fluid. At the end of the review, some challenges and development tendency of the ongoing wetting and spreading research are highlighted. [ABSTRACT FROM AUTHOR]

Janus superhydrophilic/hydrophobic macroporous nickel foam for directional water transport has been demonstrated via a simple floating strategy. Water can transport from hydrophobic to superhydrophilic layer through Janus nickel foam, but cannot transfer from superhydrophilic to hydrophobic layer. This “3D water diode” Janus nickel foam shows extremely high transport rate and outstanding stability. After damaged by abrasion, its directional water transport property retains well. [ABSTRACT FROM AUTHOR]

Superhydrophobic (SHP) coatings inspired by lotus have great application prospect for our daily life. Regrettably, three formidable challenges, namely, complex fabrication, weak mechanical stability and large-scale fabrication, have already existed for a long time in this research field. Here, a robust micro-nanoscale P25 (Nano TiO 2 )/MgO/epoxy resin (ER) SHP coating has been fabricated via facile one-pot route, which can be applied to arbitrary substrates through multiples methods. P25/MgO/ER SHP coating not only displays excellent mechanical stability but also shows unique repairable ability to recover its superhydrophobicity under various damages by extreme environment such as low temperature, strong acid or alkali and this repairable process can be repeated for many times. P25/MgO/ER SHP coating also is easy to large-scale fabrication with very low cost. [ABSTRACT FROM AUTHOR]

The development of fabrication techniques for superhydrophobic coatings is rapidly maturing, yet the problem of low mechanical durability still persists. To address this problem, we introduce a robust micro-nanoscale flowerlike ZnO/epoxy resin superhydrophobic coating possessing a rapid healing ability after ultra-abrasion. The coating was fabricated by a simple immersion method, and it presented a water contact angle above 150° and a sliding angle of less than 2°. A simple abrasion test (2400 linear abrasion times at a pressure of 5 kPa) was conducted to show that the coating could maintain superhydrophobicity, even after undergoing thirty abrasion times. Meanwhile, it could be easily repaired within one minute of the coating losing superhydrophobicity under ultra-abrasion. The abrasion only impacted the thickness of the rough structure (grown on the coating surface by immersion) and had almost no effect on the original thickness of the coating itself. This coating had an extremely long service life and may be useful for a wide range of applications. [ABSTRACT FROM AUTHOR]

The influences and treatments of oil/water mixtures have been plaguing people for many years. To deal with it, the fabrication of separation membranes becomes a significant technology in the application to oily wastewater treatment. Except for the well-known phase inversion method which is promising for polymeric separation membrane fabrication, another imaginable method referred to as in-situ elimination here still suffers from major difficulty in the uniform dispersion of dissoluble micro/nano-particles in polymeric matrix. Aiming at in-situ elimination method, a series of free-standing thin PVDF membranes with interconnected porous structures are fabricated based on low-cost starting materials through a simple process of tape-casting, drying and immersing, in the presence of pore-forming agent of citric acid monohydrate (CAM). Substantially, the pore formation mechanism is studied, which is resulted from the recrystallization of pore-forming agent (CAM) and subsequent in-situ elimination in NaHCO 3 solution. The fabricated free-standing porous PVDF membrane with thickness of ~5 µm and surface pore size of <500 nm showed great flexibility and superoleophilic, under-oil superhydrophobic, anti-water-fouling properties. For the porosity and selective wettability, their applications in oil/water separation are studied also and the results show that the PVDF membrane can separate not only immiscible oil/water mixtures quickly but also various surfactant-stabilized water-in-oil nanoscale emulsions, with filtration flux up to 318 L m −2 h −1 and separation efficiency of 99.81% under the action of self-gravity. To the best of our knowledge, this is the first time the polymeric separation membranes have been positively fabricated by in-situ elimination, which provides a new avenue for porous polymeric membrane fabrication in membrane science field and shows the application in oil/water or emulsion separation. This work provides a new porous membrane-forming method and an energy-efficient strategy for separating immiscible oil/water mixtures and surfactant-stabilized water-in-oil nano-emulsions. [ABSTRACT FROM AUTHOR]

With the development of surface science, surface with special wettability, such as reversible or gradient, gradually becomes the focus of the field of science now. Here, via a facile, green organic solvent-free route, we have fabricated superhydrophobic hybrid MWCNTs membrane on mixed cellulose ester filter with great flexibility and tailorability. Importantly, induced by acetic acid vapour and NH 3 vapour without external energy, wettability of it can be reversibly switched between superhydrophobic (low adhesion) to hydrophobic (high adhesion). Furthermore, hybrid MWCNTs membrane can achieve diverse range of gradient wettability. The principle of theory behind phenomenon also has been explained through surface chemical composition and microscopic surface topography by means of Field-emission scanning electron microscope (FESEM) images, X-ray photoelectron spectroscopy (XPS) and Fourier transformer infrared spectra (FTIR) spectroscopy. This work has solved some critical problems in this field. The limitations and potential application of our work also be summarized. [ABSTRACT FROM AUTHOR]

Recycled paper with superhydrophobicity and flame-retardancy has been demonstrated here due to the synergistic action of dopamine-silica trimethylsilyl modified gel powder and stearic acid modified Mg(OH) 2 . This multifunctional recycled paper displays great self-cleaning and anti-fouling ability and can be used for oil-water separation. Surprisingly, the absorbed organic can be reused as fuel via simple combustion method for multiple cycles. This work will not only expand the usable range of paper but also ease the energy and environment crisis. [ABSTRACT FROM AUTHOR]

It is important to explain the triboligical mechanism of solid interfaces at the atomic scale. Theoretical models developments involving atomic-scale tribology and the most classical first-principles theory for atomic-scale friction have been described. The construction of potential energy surface based on first-principle calculation is found extremely useful to unveil the tribological mechanism for atomic-scale solid sheets. Furthermore, atomic-scale tribological mechanisms exploring achievements for metals interfaces, tribo-chemisty, carbon-based solid lubrication material and 2h -MoS 2 have also been reviewed. [ABSTRACT FROM AUTHOR]

Inspired by mussels we designed a novel green superhydrophobic gel nanocoating with good transparency and stability through a facile copolymerization reaction at room temperature and a subsequent trimethyl silyl modified process, which is applicable to various substrates via a simple spray process without requiring toxic substances. Importantly, this well-designed nanocoating has rapid self-healing superhydrophobicity induced by usual organic solvents to face complicated work conditions, which satisfies the need of daily life and can be applied in industry as well. [ABSTRACT FROM AUTHOR]

Microfluidics has experienced rapid progress in additive manufacturing and microfluidic soft robots. The design of microfluidics is already moving into a more intelligent, integrated, and detachable direction. However, the pipeline resistance needs more external energy input to achieve high flow speed. Guided transport of liquid in the open‐air‐space microfluidics will be an effective solution. Inspired by the water shuttle on the pitcher plant tendril, herein, an open‐air microfluidic transport device is designed that consists of a superhydrophilic microwick with multi‐microgrooves by stereolithography. The liquid film confined in microgrooves can promote rapid fluid shuttle on the wet surface to enhance transport rate and inhibit the Rayleigh‐Plateau instability from forming larger dripping drops. The dripping volume and threshold Capillary number are optimized for effective liquid transport and drainage. State‐of‐the‐art microwick liquid shuttle technologies can guide liquid continuously in a prescribed direction or into multiple directions with 98% transport efficiency (the ratio of liquid collection volume and liquid injection volume) for water and 97% for ethanol in the closed‐open‐closed space. The proposed mechanism has the potential to streamline microfluidic applications—and, therefore, accelerate relevant liquid delivery development and ultimately their applications in microfluidic chip and additive manufacturing. [ABSTRACT FROM AUTHOR]

Highly sensitive flexible pressure sensors are extensively investigated for various applications, such as electronic skin, human physiological monitoring, and artificial intelligence. However, traditional fabrication technologies are hard to realize the large‐area and mass production of wearable sensing devices. Current trend of miniaturization, systematization, and multifunction has raised the problems of total energy consumption, frequent charging, and reduced usage time. These issues have hindered the progress of wearable sensing electronics. In the light of nanomaterial design, mass production, and facile manufacturing, electrospun piezoelectric pressure sensors offer the best properties of self‐powering, breathability, stretchability, and flexibility, providing ideal interfacing platforms for smart wearables. Tremendous advances have been achieved recently in the high sensitivity, piezoelectric output, composite optimization, and nano‐/microstructure design of nonwoven nanofiber membranes. Nevertheless, how to fulfill real textile‐level integration in consideration of biocompatibility, integration, wearability, geometrical design, multifunction, and systematization remains a big challenge. Therefore, recent progress of piezoelectric pressure sensors from electrospun nanofibers to their fabrics is comprehensively summarized. Plentiful strategies, structure designs, and underlying mechanisms that boost the piezoelectric properties are discussed. Lastly, the challenges and possible solutions for the future electrospinning‐based pressure sensing systems are proposed. [ABSTRACT FROM AUTHOR]

Review: 67 refs. [ABSTRACT FROM AUTHOR]

Although the development of superhydrophobic coatings is rapidly maturing, issues related to their low mechanical durability persist. In this context, the effect of substrate roughness on the service life of superhydrophobic coatings was studied. In this study, superhydrophobic coatings were fabricated on sandpapers of different roughness and reciprocating wear tests were conducted. The wear-resistance number of the superhydrophobic coating, defined as the maximum number of friction cycles after which the superhydrophobic surface started to lose its superhydrophobicity, increased from 50 to 24,000 with an increase in the substrate roughness from 2000 CW to 240 CW (CW is defined as the number of particles arranged in an inch), while it decreased from 24,000 to 17,000 with a further increase in the substrate roughness from 240 CW to 60 CW. Observations of the surface structure and wear analyses indicated that the superhydrophobic material infiltrated the spaces between the sand grains, and the rough peaks could consequently protect the superhydrophobic material during the wear tests. However, this protection weakens when the substrate roughness increases or decreases beyond certain values. Furthermore, these phenomena and results were also verified by applying the superhydrophobic coatings to different types of common substrates. [ABSTRACT FROM AUTHOR]

Highlights: Bioinspired directional moisture-wicking electronic skin (DMWES) was successfully realized by surface energy gradient and push–pull effect via the design of distinct hydrophobic-hydrophilic difference. The DMWES membrane showed excellent comprehensive pressure sensing performance with high sensitivity and good single-electrode triboelectric nanogenerator performance The superior pressure sensing and triboelectric performance enabled the DMWES for all-range healthcare sensing, including accurate pulse monitoring, voice recognition, and gait recognition. Electronic skins can monitor minute physiological signal variations in the human skins and represent the body's state, showing an emerging trend for alternative medical diagnostics and human–machine interfaces. In this study, we designed a bioinspired directional moisture-wicking electronic skin (DMWES) based on the construction of heterogeneous fibrous membranes and the conductive MXene/CNTs electrospraying layer. Unidirectional moisture transfer was successfully realized by surface energy gradient and push–pull effect via the design of distinct hydrophobic-hydrophilic difference, which can spontaneously absorb sweat from the skin. The DMWES membrane showed excellent comprehensive pressure sensing performance, high sensitivity (maximum sensitivity of 548.09 kPa−1), wide linear range, rapid response and recovery time. In addition, the single-electrode triboelectric nanogenerator based on the DMWES can deliver a high areal power density of 21.6 µW m−2 and good cycling stability in high pressure energy harvesting. Moreover, the superior pressure sensing and triboelectric performance enabled the DMWES for all-range healthcare sensing, including accurate pulse monitoring, voice recognition, and gait recognition. This work will help to boost the development of the next-generation breathable electronic skins in the applications of AI, human–machine interaction, and soft robots. [ABSTRACT FROM AUTHOR]

In the past few years, bioinspired eco-friendly superhydrophobic materials (EFSMs) have made great breakthroughs, especially in the fields of environment, energy and biology, which have made remarkable contributions to the sustainable development of the natural environment. However, some potential challenges still exist, which urgently need to be systematically summarized to guide the future development of this field. Herein, in this review, initially, we discuss the five typical superhydrophobic models, namely, the Wenzel, Cassie, Wenzel–Cassie, "lotus", and "gecko" models. Then, the existence of superhydrophobic creatures in nature and artificial EFSMs are summarized. Then, we focus on the applications of EFSMs in the fields of environment (self-cleaning, wastewater purification, and membrane distillation), energy (solar evaporation, heat accumulation, and batteries), and biology (biosensors, biomedicine, antibacterial, and food packaging). Finally, the challenges and developments of eco-friendly superhydrophobic materials are highlighted. [ABSTRACT FROM AUTHOR]

An ideal wound dressing should include excellent physical property, comfortability, and protection. Critical properties, such as robust tensile stress, high water vapor transmission rate (WVTR), air permeability (AP), waterproofness, biocompatibility, and particle filtration efficiency (PFE) should be covered. However, previous research regarding wound dressings omitted some of these elements, leading to the fact that wound healing management was ineffective. Herein, inspired by human skin structure, we designed a skin-like wound dressing with a hydrophilic healing interlayer and a hydrophobic protective surface based on polyvinylidene fluoride. The prepared membrane not only possesses an excellent physical property, comfortability, and protective function but also can accelerate cell migration and the wound healing process. Particularly, the dressing demonstrates robust tensile stress of 25.9 MPa, a toughness of 12.2 MJ/m3, a typical WVTR over 17.4 kg/(m2·d), a high AP of 4.2 mL/s, a high PFE of 99.9%, excellent biocompatibility, and a more rapid scratch healing rate than the commercial product, Nexcare. The dressing is proven to be similar to human skin (i.e., tensile strength of 21.6 ± 8.4 MPa and failure strain of 54 ± 17%). We believe that the achieved scalable nanostructured membrane can make meritorious contributions to materials science and biomedical engineering. [ABSTRACT FROM AUTHOR]