The controllable transport of fluids as well as bubbles is the cornerstone of various bioprocesses and microporous technology applications, with a wide range of applications in microfluidics, bioassays, gas transport, and oil–water separation technologies. Although functional modulation of solid surfaces to achieve different surface responses for directional manipulation of microfluidics has been extensively investigated, non-contact bubble/droplet directional manipulation remains a challenge in this field. Here, we report a simple candle soot deposition method to construct oil-filled surface nanoroughness, achieve the combination of oil-locking performance and photothermal response performance on the polydimethylsiloxane (PDMS) surface, and produce a near-infrared light (NIL)-responsive soot nanoskeleton oil-filled surface (NSNOS), which can be effectively applied to the directional manipulation of droplets and bubbles. Soot nanoparticles act as a backbone to support the SiO₂ shell to provide structural stability, whereas Fe₃O₄ nanoparticles combine to provide the surface with excellent NIL photothermal response properties. It can be heated to more than 150 °C within 60 s. Precise droplet/bubble orientation manipulation is thus achieved. Through the localized thermal response to near-infrared light, we can control droplets and bubbles to achieve anti-gravity and anti-buoyancy motions with precise, controllable trajectories. We believe that this work provides important insights for the development of smart droplet/bubble micromanipulation.

In recent years, miniature robots have shown remarkable potential for applications in the fields of in vivo drug delivery, disease treatment, and extreme environment sensing. However, due to their high structural rigidity, poor biocompatibility, low adaptability in complex terrains, and lack of active obstacle avoidance, traditional synthetic miniature robots can usually only be investigated for proof-of-concept studies while ignoring their in vivo safety or the complexity of the application environments, which is still a significant gap from the needs of practical applications in vivo or in extreme environments. Due to their superior biocompatibility and living biological function, living biohybrid miniature robots (LBMs) have great clinical applications in vivo disease diagnosis and treatment, and in extreme environment sensing, search, and rescue. They have environmental adaptive capabilities comparable to natural organisms, thus maximizing the functionality and locomotor capabilities of living organisms. Here, we systematically summarize the components and fabrication strategies of LBMs, and comprehensively discuss the driving modes of them, as well as the efficient goal-oriented realization of these mechanisms in specific application scenarios. Finally, we discuss the current challenges facing the field and provide an outlook on future developments and research directions.

The poor wear performance and susceptibility to pitting corrosion of titanium alloys in practical applications have attracted increasing attention. Layered double hydroxides (LDH) coatings, with two-dimensional structure, have shown great potential in protecting metals from corrosion and wear. However, the dense oxide layer on titanium alloys has hindered the development of LDH on these materials. In this study, a ZnAl LDH coating was fabricated on the surface of TC4 alloy via an in situ growth method. Molybdic acid anions were subsequently incorporated into the LDH interlayer through an ion exchange process. Inspired by biomimetic principles, a UV-grafted PDMS-infused slippery surface was prepared based on the nanoporous structure of ZnAl LDH, resulting in a protective surface with excellent hydrophobicity, corrosion resistance, and wear resistance. The anti-corrosion performance of the surface was evaluated using Tafel polarization and electrochemical impedance spectroscopy (EIS). The results demonstrated excellent corrosion protection for the TC4 substrate, as indicated by a low corrosion current density of 2.34 × 10^-7 A/cm². Compared with the bare TC4 alloy, the modified surface exhibited improved improved wear performance, owing to the infused silicone oil and ZnAl LDH nanosheets. This work not only provides valuable insights into the controllable in situ fabrication of LDH coatings but also offers a new strategy for the broader application of TC4 alloys and further research in the field of metal protection.

Friction phenomena are strongly affected by interfacial mechanical and tribochemical effects, which involve major factors such as loads, sliding rates, sliding times, humidity, temperatures, and oxide films. For practical applications at different vacuum levels, friction mechanisms (adhesive wear, abrasive wear, fatigue wear, corrosive wear, and micromotor wear) are highly important for the development of advanced materials with desirable tribological properties to promote vacuum tribology. In this review, in combination with the current understanding of friction‒wear interactions, the tribological phenomena caused by changes in the surfaces of friction pairs that are highly dependent on complex conditions in different vacuum environments are analyzed and summarized. Subsequently, protection strategies for different structural materials are summarized. Finally, this work provides an outlook for designing advanced and sustainable protective materials under different vacuum conditions.

The lack of freshwater resources is a global problem. Fast and efficient water capture from fog is a good solution for many organisms living in arid regions. Compared with superhydrophobic surfaces, slippery liquid-filled porous surfaces (SLIPS) exhibit excellent droplet transport and shedding properties with very low sliding angles (SAs). It is not easy to produce a water film which can effectively improve the efficiency of fog collection. The shape and size of the micro/nanostructure are flexibly adjusted by laser etching, the nanowires on the micron-scale pillars and groove structure are uniformly covered by ammonia etching, and silicone oil is injected by spin-coating to obtain a slippery liquid-infused surface with a micro/nanostructure. Under the synergistic effect of our constructed micro/nanostructure, the superhydrophobic surface injected with lubricant exhibited efficient droplet capture, aggregation, and removal properties, which greatly improved the fog collection efficiency (107% higher than that of the original sample). More importantly, the surface has excellent stability, ice resistance, and acid/alkali resistance and is expected to be used in various extreme adjustments.

With the global population growing, energy demand has increased drastically. Simultaneously, environmental concerns have been increasing at an alarming rate. In transportation systems such as pipelines and ships, the resistance caused by friction is a major factor leading to energy loss. This not only leads to high energy consumption but also hinders improving the overall efficiency of transportation processes. Therefore, finding a solution to minimize this energy loss has emerged as a critical research area among scholars. A viable solution inspired by the unique structures in nature is deemed an effective drag reduction method. This paper outlines the bionic structures of earthworms, sharks, and dolphins and discusses their theory and mechanism for reducing drag. Furthermore, this paper compares recent approaches employing bionic drag–reduction interfaces based on earthworm, shark, and dolphin body structures. The applications of bionic interfacial drag reduction materials in agriculture, transportation, and industry are also analyzed, along with a summary of the limitations and challenges associated with bionic interfacial drag reduction. Finally, the authors look forward to future research directions and application prospects of bionic interfacial drag reduction materials.

Untethered and self-transformable miniature robots are capable of performing reconfigurable deformation and on-demand locomotion, which aid the traversal toward various lumens, and bring revolutionary changes for targeted delivery in gastrointestinal (GI) tract. However, the viscous non-Newtonian liquid environment and plicae gastricae obstacles severely hamper high-precision actuation and payload delivery. Here, we developed a low-friction soft robot by assembly of densely arranged cone structures and grafting of hydrophobic monolayers. The magnetic orientation encoded robot can move in multiple modes, with a substantially reduced drag, terrain adaptability, and improved motion velocity across the non-Newtonian liquids. Notably, the robot stiffness can be reversibly controlled with magnetically induced hardening, enabling on-site scratching and destruction of antibiotic-ineradicable polymeric matrix in biofilms with a low-frequency magnetic field. Furthermore, the magnetocaloric effect can be utilized to eradicate the bacteria by magnetocaloric effect under high-frequency alternating field. To verify the potential applications inside the body, the clinical imaging-guided actuation platforms were developed for vision-based control and delivery of the robots. The developed low-friction robots and clinical imaging-guided actuation platforms show their high potential to perform bacterial infection therapy in various lumens inside the body.

Oil pollution and the energy crisis make oil-water separation an urgent for human need. The widespread use of materials with a single emulsion separation capability is limited. Multifunctional on-demand separation materials can adapt to a wide range of application scenarios, thus having a wider range of applications. The underoil superhydrophilic surface is of great significance for realizing the on-demand separation of oil/water emulsions through the removal of water in the oil and oil in the water. A 3D porous emulsion separation material based on the superhydrophilic principle of sphagnum moss was designed. The material was prepared in a simple step by taking advantage of the adhesion of polydopamine and the introduction of the as-prepared superhydrophilic BaSO₄ nanoparticles to achieve superhydrophilicity with a water contact angle (WCA) of 0° and an oil contact angle (OCA) of 157.3°, resulting in excellent separation performance for both water-in-oil and oil-in-water emulsions. Underoil superhydrophilic porous composite (OSPC) can complete two kinds of emulsion separations by filtration or adsorption. It adsorbs water from water-in-oil emulsion to achieve separation, with a good adsorption capacity of 74.38 g/g and efficiency up to 99%. It can also filter oil-in-water emulsions with an efficiency of 99.92%. The separation efficiencies are all almost unchanged after ten separation cycles. Furthermore, the material has excellent flame retardancy, which reduces the possibility of secondary disasters. The three-dimensional porous sponge has excellent on-demand separation performance for multiple emulsions. It provides a new preparation strategy for underoil superhydrophilic materials and a new idea for the design direction of special wetting materials for the on-demand separation of oil/water emulsions.

The separation of oil-in-water emulsion is an urgent challenge because its massive production and discharge from daily and industrial activities have caused severe hazards to the ecosystem and serious threats to human health. Membrane technology is considered an outstanding solution strategy for the separation of oil-in-water emulsions due to its unique advantages of low cost, high efficiency, easy operation, and environmental friendliness. However, the membrane is easily fouled by the emulsion oil droplets during the separation process, causing a sharp decline in permeation flux, which greatly inhibits the long-term use of the membrane and largely shortens the membrane’s life. Recently, it was found that endowing the membranes with special wettability e.g., superhydrophilic and superoleophobic can greatly enhance the permeability of the continuous water phase and inhibit the adhesion of oil droplets, thus promoting the separation performance and anti-oil-fouling property of membrane for oily emulsions. In this paper, we review and discuss the recent developments in membranes with special wettability for separating oil-in-water emulsions, including the mechanism analysis of emulsion separation membrane, membrane fouling issues, design strategies, and representative studies for enhancing the membrane’s anti-oil-fouling ability and emulsion separation performance.

Lubricants are often contaminated by water in different ways. Water-polluted lubricants extremely accelerate wear corrosion, leading to the deterioration of lubricity performance. Recently, multiphase media superwettability has been developed to endow one surface with compatible functions, such as on-demand separation of oily wastewater. However, realizing the robustness of the dual superlyophobic surface to solve water-caused lubricant deterioration and water contamination as needed remains challenges. Herein, a robust dual superlyophobic membrane is presented to realize on-demand separation for various lubricant–water emulsions. Compared to pure lubricants, the purified lubricants have equivalent tribology performance, which are much better than that of water-polluted lubricants. The as-prepared membrane maintains dual superlyophobicity, high-efficient for water or lubricant purification, and excellent tribology performance of the purified lubricant, even after immersion in hot liquids for 24 h, multicycle separation, and sandpaper abrasion for 50 cycles. Water-polluted lubricant extremely accelerates wear corrosion to promote catalytic dehydrogenation of lubricants, generating too much harmful carbon-based debris. This work shows great guiding significance for recovering the tribology performance of water-polluted lubricants and purifying water by the dual superlyophobic membrane.