Infinite Self-Propulsion of Circularly On/Discharged Droplets

Self-propulsion of droplets in a controlled and long path at a high-speed is crucial for organic synthesis, pathological diagnosis and programable lab-on-a-chip. To date, extensive efforts have been made to achieve droplet self-propulsion by asymmetric gradient, yet, existing structural, chemical, or charge density gradients can only last for a while (<50 mm). Here, this work designs a symmetrical waved alternating potential (WAP) on a superhydrophobic surface to charge or discharge the droplets during the transport process. By deeply studying the motion mechanisms for neutral droplets and charged droplets, the circularly on/discharged droplets achieve the infinite self-propulsion (>1000 mm) with an ultrahigh velocity of meters per second. In addition, after permutation and combination of two motion styles of the droplets, it can be competent for more interesting work, such as liquid diode and liquid logic gate. Being assembled into a microfluidic chip, the strategy would be applied in chemical synthesis, cell culture, and diagnostic kits.

Noncontact Microfluidics of Highly Viscous Liquids for Accurate Self-Splitting and Pipetting

Accurate dosing for various liquids, especially for highly viscous liquids, is fundamental in wide-ranging from molecular crosslinking to material processing. Despite droppers or pipettes being widely used as pipetting devices, they are powerless for quantificationally splitting and dosing highly viscous liquids (>100 mPa s) like polymer liquids due to the intertwined macromolecular chains and strong cohesion energy. Here, a highly transparent photopyroelectric slippery (PS) platform is provided to achieve noncontact self-splitting for liquids with viscosity as high as 15 000 mPa s, just with the assistance of sunlight and a cooling source to provide a local temperature difference (ΔT). Moreover, to guarantee the accuracy for pipetting liquids (>80%), the ultrathin MXene film (within a thickness of 20 nm) is self-assembled as the photo-thermal layers, overcoming the trade-off between transparency and photothermal property. Compared with traditional pipetting strategies (≈1.3% accuracy for pipetting polymer liquids), this accurate microfluidic chip shows great potential in adhesive systems (bonding strength, twice than using the droppers or pipettes).

Light-Induced Dynamic Manipulation of Liquid Metal Droplets in the Ambient Atmosphere

Dynamic manipulation of liquid metal (LM) droplets, a material combining metallicity and fluidity, has recently revealed tremendous potential in developing unconstrained microrobots. LM manipulating techniques based on magnetic fields, electric fields, chemical reactions, and ion concentration gradients in liquid environments have advanced considerably, but dynamic manipulation in air remains a challenge. Herein, a photoresponsive pyroelectric superhydrophobic (PPS) platform is proposed for noncontact, flexible, and controllable manipulation in the ambient atmosphere. The PPS can generate additional free charges when illuminated by light, thus generating the driving force to manipulate liquid metal droplets. By using the synergistic effect of dielectrophoretic and electrostatic forces generated under light navigation, liquid metal droplets can achieve a series of complex motion behaviors, such as climbing slopes, going over steps, avoiding obstacles, crossing mazes, etc. We further extend the light control of liquid metal droplets to robots applied in electronic circuits, including circuit switching robots and circuit welding robots. This light strategy for manipulating liquid metal droplets provides insights into the development of intelligent, responsive interfaces and simultaneously provides possibilities for the application of liquid metals.

Photoelectric synergistic anisotropic slippery interface for directional droplets manipulation

Stimuli-responsive anisotropic slippery surfaces have displayed remarkable performance in directionally manipulating droplet transport behavior. However, most current reported anisotropic slippery materials have been limited to a single response mode, which often fails to satisfy the practical conditions of double or synergetic stimulation in complex environments. Here, an anisotropic photoelectric synergistic responsive paraffin-injected directional oxidized copper foam slippery interface (P/DOC3-S) with a low response threshold is reported. Owing to the fast photoelectric response of P/DOC3-S, the reversible control of the anisotropic sliding behavior of droplets is realized by remotely switching on and off the photoelectric field. Additionally, through optimizing the structure, the response voltage for P/DOC3-S can be reduced to 0.3 V under one sunlight. This work will provide insights into creating new types of smart slippery surfaces, which are potentially useful in microfluidics, directional liquid transportation, the semiconductor industry, and other related fields.

Slippery Graphene-Bridging Liquid Metal Layered Heterostructure Nanocomposite for Stable High-Performance Electromagnetic Interference Shielding

Gallium-based liquid metal (LM) with intriguing high electrical conductivity and room-temperature fluidity has attracted substantial attention for its potential application in flexible electromagnetic interference (EMI) shielding. However, the EMI shielding performance of the existing LM-based composites is unsatisfying due to the irreconcilable contradiction between high EMI shielding efficiency (SE) and low thickness. In addition, the research on environmentally stable EMI shielding material has become an urgent need due to the increasingly sophisticated application scenarios. Herein, we prepared a reduced graphene oxide (rGO) bridging LM layered heterostructure nanocomposite with the liquid-infused slippery surface (S-rGO/LM), which exhibits an ultrahigh X-band EMI SE of 80 dB at a mere internal thickness of 33 μm, and an extremely high value of 100 dB at an internal thickness of 67 μm. More significantly, protected by the ultrathin (2 μm) yet effective slippery surface, the S-rGO/LM film exhibits exceptional EMI shielding stability (EMI SE stays above 70 dB) after enduring various harsh conditions (harsh chemical environments, extreme operating temperatures, and severe mechanical wearing). Moreover, the S-rGO/LM film also demonstrates satisfying photothermal behavior and excellent Joule heating performance (surface temperature of 179 °C at 1.75 V, thermal response <10 s), which endows it with the capability of anti-icing/de-icing. This work proposes a way to construct an LM-based nanocomposite with reliable high-performance EMI shielding capability, which shows great potential for applications in wearable devices, defense, and aeronautics and astronautics.

Noncontact Charge Shielding Knife for Liquid Microfluidics

Multibehavioral droplet manipulation in a precise and programmed manner is crucial for stoichiometry, biological virus detection, and intelligent lab-on-a-chip. Apart from fundamental navigation, merging, splitting, and dispensing of the droplets are required for being combined in a microfluidic chip as well. Yet, existing active manipulations including strategies from light to magnetism are arduous to use to split liquids on superwetting surfaces without mass loss and contamination, because of the high cohesion and Coanda effect. Here, we demonstrate a charge shielding mechanism (CSM) for platforms to integrate with a series of functions. In response to attachment of shielding layers from the bottom, the instantaneous and repeatable change of local potential on our platform achieves the desired loss-free manipulation of droplets, with a wide-ranging surface tension from 25.7 mN m^-1 to 87.6 mN m^-1, functioning as a noncontact air knife to cleave, guide, rotate, and collect reactive monomers on demand. With further refinement of the surface circuit, the droplets, just as the electron, can be programmed to be transported directionally at extremely high speeds of 100 mm s^-1. This new generation of microfluidics is expected to be applied in the field of bioanalysis, chemical synthesis, and diagnostic kit.

Photothermal Solid Slippery Surfaces with Rapid Self-Healing, Improved Anti/De-Icing and Excellent Stability

Icing phenomenon that occurs universally in nature and industry gets a great impact on human life. Over the past decades, extensive efforts have been made for a wide range of anti-icing/deicing surfaces, but the preparation of anti-icing/deicing interfaces that combine stability, rapid self-healing and excellent anti-icing/deicing performance remains a challenge. In this study, a photothermal solid slippery surface with excellent comprehensive performance is prepared by integrating cellulose acetate film, carbon nanotubes with paraffin wax (CCP). Apart from the excellent anti-icing and deicing properties at -17 ± 1.0 °C under 1 sun illumination, the surface can further achieve deicing at temperatures as low as -22 ± 1.0 °C under infrared light. The fabricated surface also exhibits great stability when placed in harsh conditions such as underwater or ultra-low temperature environments for over 30 days. Even when suffering from physical damage, the prepared surface can rapidly self-repair under 1 sun illumination or near-infrared (NIR) illumination within 16.0 ± 1.5 s. Due to the rapid and repeatable self-healing performance, the lubricating properties of the interface material do not deteriorate even after 50 repeated abrasing-repairing cycles. The photothermal solid slippery surface possesses wide-ranging applications and commercial value at high latitude and altitude regions.

Slippery Surface Based on Photoelectric Responsive Nanoporous Composites with Optimal Wettability Region for Droplets' Multifunctional Manipulation

The development of responsive slippery surfaces is important because of the high demand for such materials in the fields of liquid manipulation on biochips, microfluidics, microreactions, and liquid-harvesting devices. Although great progress has been achieved, the effect of substrate wettability on slippery surfaces stability is overlooked by scientists. In addition, current responsive slippery surfaces generally function utilizing single external stimuli just for imprecisely controlling liquid motion, while advanced intelligences are always expected to be integrated into one smart interface material for widespread multifunctional applications. Therefore, designing slippery surfaces that collaboratively respond to complex external stimuli and possess sophisticated composite function for expanding applications from controlling droplets motion to patterned writing is urgently needed but remains a challenge. Here, a photoelectric cooperative-responsive slippery surface based on ZnO nanoporous composites is demonstrated. First, the effect of composite surface wettability on slippery surface stability is systematically researched and the optimum wettability region for fabricating stable slippery surfaces is determined. Furthermore, controllable droplet motion and patterned writing are realized on the same slippery surfaces under photoelectric cooperative stimuli, and the related response mechanism is also deeply studied. This kind of material has potential applications in biochips, microfluidics, in situ patterning, and water-harvesting systems.

Tough Reversible Adhesion Properties of a Dry Self-Cleaning Biomimetic Surface

Geckos have one of the world's most efficient reversible adhesion systems. Even walking in dusty conditions, geckos can dislodge up to 80% of contaminants and recover their adhesion capability after walking as few as four steps. Thus far, artificial dry self-cleaning materials inspired by the geckos' hierarchical fibrillar structure have been only able to remove 55% of collected large particle contaminants with 30 steps. Challenges, including low mechanical strength, low stiffness, and short fatigue time keep these materials from being used in practical applications. This study involves the novel fabrication of dry self-cleaning surfaces with a high mechanical performance and an outstanding dry self-cleaning property. Imposing a load-drag-pull process similar to a gecko's foot adhesion process, our biomimetic surfaces could dislodge up to 59% of microparticles (∼8 μm) with as few as five steps. Furthermore, the surface had an excellent screening ability at low temperatures regardless of the surface roughness similarity. The surfaces were also proven to be scratch resistant. The biomimetic surfaces exhibit enhanced dry self-cleaning and mechanical properties and could be promising in applications such as reusable adhesives, biochips, aerospace satellite waste collection, and screening equipment.

Preparation of Polyurethane/Graphite Composite Films with Stable Mechanical Property and Wear Resistance Underwater

The wear resistance and stable mechanical properties affect the service life of the underwater functional materials to a certain extent. Unfortunately, the current study of underwater functional materials is rarely related to these aspects. Herein, we successfully designed and prepared polyurethane/graphite nanosheet (PU/GN) composite materials, which exhibited excellent wear resistance and stable mechanical properties underwater. The PU/GN composite films were prepared by evaporating a mixed solution of PU and GN on concave hexagonal honeycomb silicon templates. The mechanical properties of the composite films were determined by tensile test, and the wear resistance was evaluated by comparing the surface morphology before and after grind. By adjusting the content of graphite in the composite films, we found that the composite films containing 23 wt% GN had higher tensile strength and superior wear resistance. Moreover, this composite film showed an outstanding stability when expose to water. The impressive results along with simple preparation process made PU/GN composite films had potential applications in robust underwater functional materials.

Underwater Mechanically Robust Oil-Repellent Materials: Combining Conflicting Properties Using a Heterostructure

The development of underwater mechanically robust oil-repellent materials is important due to the high demand for these materials with the increase in underwater activities. Based on the previous study, a new strategy is demonstrated to prepare underwater mechanically robust oil-repellent materials by combining conflicting properties using a heterostructure, which has a layered hydrophobic interior structure with a columnar hierarchical micro/nanostructure on the surface and a hydrophilic outer structure. The surface hydrophilic layer imparts underwater superoleophobicity and low oil adhesion to the material, which has oil contact angle of larger than 150° and adhesion of lower than 2.8 µN. The stability of the mechanical properties stemming from the interior hydrophobic-layered structure enables the material to withstand high weight loads underwater. The tensile stress and the hardness of such a heterostructure film after 1 month immersion in seawater and pH solution are in the range from 83.92 ± 8.22 to 86.73 ± 7.8 MPa and from 83.88 ± 6.8 to 86.82 ± 5.64 MPa, respectively, which are superior to any underwater oil-repellent material currently reported.

Temperature-Responsive Anisotropic Slippery Surface for Smart Control of the Droplet Motion

Development of stimulus-responsive anisotropic slippery surfaces is important because of the high demand for such materials in the field of liquid directional-driven systems. However, current studies in the field of slippery surfaces are mainly conducted to prepare isotropic slippery surfaces. Although we have developed electric-responsive anisotropic slippery surfaces that enable smart control of the droplet motion, there remain challenges for designing temperature-responsive anisotropic slippery surfaces to control the liquid droplet motion on the surface and in the tube. In this work, temperature-responsive anisotropic slippery surfaces have been prepared by using paraffin, a thermo-responsive phase-transition material, as a lubricating fluid and directional porous polystyrene (PS) films as the substrate. The smart regulation of the droplet motion of several liquids on this surface was accomplished by tuning the substrate temperature. The uniqueness of this surface lies in the use of an anisotropic structure and temperature-responsive lubricating fluids to achieve temperature-driven smart control of the anisotropic motion of the droplets. Furthermore, this surface was used to design temperature-driven anisotropic microreactors and to manipulate liquid transfer in tubes. This work advances the understanding of the principles underlying anisotropic slippery surfaces and provides a promising material for applications in the biochip and microreactor system.

Wettability with Aggregation-Induced Emission Luminogens

Aggregation-induced emission luminogens (AIEgens) have become an emerging field since the concept of AIE was proposed in 2001. Recently, AIEgens have attracted considerable attention due to their abnormal non-emissive fluorescent behavior in solution but strongly emissive behavior in the aggregate state. By utilizing the inherent hydrophobicity, AIEgens can be used to monitor the crystal formation and dewetting behavior in the self-assembly process. More importantly, some stimuli-responsive AIE-active surfaces have been successfully fabricated. In this perspective review, we outline the advances of surface wettability of AIEgens and its applications.

Super water absorbency OMMT/PAA hydrogel materials with excellent mechanical properties

Montmorillonite/poly(acrylic acid) composite hydrogels, fabricated through UV irradiation polymerization, have a super water absorbency of 2786 g g⁻¹ and excellent mechanical properties.

Multiphase Media Antiadhesive Coatings: Hierarchical Self-Assembled Porous Materials Generated Using Breath Figure Patterns

The cleaning of interface pollutants typically consumes a large amount of energy. Therefore, the development of multiphase media antiadhesive materials is urgently required to meet the demand of energy savings and environmental protection. In this study, the antiadhesive properties toward several liquid droplets and bubbles in multiple media are demonstrated on a porous Fe₂O₃ coating, which is prepared via a facile spin-coating-assisted breath figure approach and a phase separation strategy. The prominent antiadhesive characteristic of these porous surfaces lies in their high-surface-energy hierarchical micro/nanoscale structure, which easily entraps one medium (oil or water) in the pore and repels other unmixable liquids and air bubbles. In addition, we successfully demonstrate an antifouling application of the coating, which shows excellent antiadhesive and super-antiwetting characteristics under multiple liquids. Our work extends relevant antiadhesion research from a single medium to multiple media and promises to broaden the applications of antiadhesive materials in sophisticated activities performed under complicated liquid environments, such as marine antifouling or pipeline transportation.

Robust Underwater Oil-Repellent Material Inspired by Columnar Nacre

Inspired by natural columnar nacre, artificial montmorillonite/hydroxyethyl cellulose columnar nacre-like materials with a site-specific layered structure in the interior and a hierarchical columnar structure on the surface are prepared. The materials exhibit improved tensile strength, good chemical stability in seawater, superior resistance to sand-grain impingement, and robust underwater low-adhesive superoleophobicity.

Anisotropic Slippery Surfaces: Electric-Driven Smart Control of a Drop's Slide

Anisotropic slippery surfaces composed of directional, porous, conductive poly(3-hexylthiophene) (P3HT) fibers, and silicone oil exhibit excellent anisotropic sliding properties for several liquid droplets and the reversible control of conductive liquid droplets sliding on these surfaces under the application of voltage.

Strengthening of polymer ordered porous materials based on a layered nanocomposite internal structure

Ordered porous polymeric films attract more and more attention because they have many advantages and broad application prospects in many fields. But because of their large flexibility and poor mechanical properties, some of the scope for application is greatly limited. Inspired by the ordered pore structure of the honeycomb and the layered structure of natural nacre, we prepared an ordered porous polymer film with a layered structure in the pore wall by the solvent-evaporation-restriction assisted hard template method. Compared with other samples, this kind of film with the layered structure showed both excellent mechanical properties and good stability. This kind of film with high mechanical strength, is considered to have wide applications in the areas of separation, biomedicine, precision instruments, aerospace, environmental protection and so on.

Biomimetic heterogeneous multiple ion channels: a honeycomb structure composite film generated by breath figures

We design a novel type of artificial multiple nanochannel system with remarkable ion rectification behavior via a facile breath figure (BF) method. Notably, even though the charge polarity in the channel wall reverses under different pH values, this nanofluidic device displays the same ionic rectification direction. Compared with traditional nanochannels, this composite multiple ion channel device can be more easily obtained and has directional ionic rectification advantages, which can be applied in many fields.

Special adhesion of natural honeycomb walls and their application

In this paper, we investigated the wettability and adhesive behavior of the natural honeycomb wall for water and honey droplets. The cell walls have hydrophobic and highly adhesive properties for both water and honey in air. This highly adhesive cell wall was used as a "mechanical hand" to transfer micro-droplets. These findings will help us to comprehensively understand the surface properties of honeycomb walls, and will provide a novel strategy for achieving functional biomimetics based on honeycombs.

Wettability and permeation of ethanol/water mixture on porous mesh surface

A serial of copper meshes with different chemical composition and roughness was prepared by modifying different mixed thiols, which showed different wetting behavior and permeation behavior for different ethanol/water mixed solution.

Conductive Polymer Porous Film with Tunable Wettability and Adhesion

A conductive polymer porous film with tunable wettability and adhesion was fabricated by the chloroform solution of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyricacid-methyl-ester (PCBM) via the freeze drying method. The porous film could be obtained from the solution of 0.8 wt%, whose pore diameters ranged from 50 nm to 500 nm. The hydrophobic porous surface with a water contact angle (CA) of 144.7° could be transferred into a hydrophilic surface with CA of 25° by applying a voltage. The water adhesive force on the porous film increased with the increase of the external voltage. The electro-controllable wettability and adhesion of the porous film have potential application in manipulating liquid collection and transportation.

Polymer porous interfaces with controllable oil adhesion underwater

Porous montmorillonite (MMT)/poly acrylic acid (PAA) composite surfaces with different oil adhesions were achieved by controlling the MMT arrangement in the pore wall.

Design of honeycomb structure surfaces with controllable oil adhesion underwater

We fabricate honeycomb-like poly acrylic acid (PAA) surfaces and achieve oil adhesion regulation underwater by changing the pore size and the solution pH, which affect triple-phase contact line (TCL) continuity and the negative pressure in the pores.

A visual and organic vapor sensitive photonic crystal sensor consisting of polymer-infiltrated SiO2 inverse opal

Tetraphenylethene polymer-infiltrated SiO₂ inverse opal can detect tetrahydrofuran/acetones vapors according to the color change, which is resulted from the adsorption–desorption of vapors.

Ordered porous structure hybrid films generated by breath figures for directional water penetration

A highly ordered open-pore hybrid film was fabricated by controlling the substrate roughness and wettability. The composite with different wettability on the two side resulted in an attractive unidirectional water-penetration function (see figure).

Chemically controllable fabrication of one-dimensional ZnO nanostructures and their applications in solar cells

One-dimensional (1D) ZnO nanostructures have attracted much attention due to their interesting optical and electronic properties, which make them suitable for a wide variety of current and future technological applications, including photodetectors, photovoltaics, photocatalysis, field emissions, gas sensors and solar cells. This review gives a comprehensive overview of recent developments in chemically controllable fabrication of 1D ZnO nanomaterials. We will cover the synthetic techniques including chemical vapor deposition (CVD), metal-organic chemical vapor deposition (MOCVD), hydrothermal technique, solvothermal synthesis, sol-gel method, electrochemical deposition, and nanosphere lithography technique. Finally, we will also highlight their application in the energy conversion system.

Ordered honeycomb structural interfaces for anticancer cells growth

The patterned honeycomb structure film with the aggregation-induced emission property was prepared successfully by the breath figure method and photopolymerization method. Characterization of the HeLa and HepG2 cell culture on this surface indicates the porous honeycomb structures show anticancer cells growth function. So this kind of honeycomb structure will be promising for the control of cancer cell growth behaviors and achieving the application of anticancer.

Bioinspired design of honeycomb structure interfaces with controllable water adhesion

Inspired by biological attachment systems, we fabricated the honeycomb structural films with different diameters by breath figure (BF) method, which were similar to the patterned octopus suckers. The experimental results showed, besides different van der Waals forces between the polystyrene (PS) surfaces and water, another important factor; that is, different negative pressures produced by different volumes of sealed air could be a crucial factor for the different adhesions. So the water adhesive forces of the as-prepared films can be effectively controlled from relative high to relative low adhesion by varying the pore diameters, which effectively adjusted the negative pressures produced by the pores. This unique adhesive phenomenon of honeycomb structure will be very useful for manipulating water droplet behaviors, as well as controlling liquid collection and transportation. These findings are interesting and helpful for us to further understand the biological attachment systems and to optimize the design of artificial analogues.

Thermoresponsive wettability of photonic crystals fabricated by core-shell poly(styrene-acrylamide) nano/microspheres

The photonic crystals (PCs) films with tunable wettability were fabricated from self-assembly of an amphiphilic latex nano/microspheres poly(styrene-acrylamide) at different temperatures. The results demonstrate that the surface wettability of the PCs film can be tuned from high hydrophilic (CA, 17 degrees) to high hydrophobic (CA, 127.8 degrees) by controlling the assembly temperature from 30 degrees C to 90 degrees C, while the position of the photonic stopbands of the PCs films unchanged virtually. The obvious wettability transition is due to the change of the surface chemical component of the latex spheres, which mainly derives from the phase separation of polymer segments driven toward minimum interfacial energy. The facile method could open new application fields of PCs in diverse environments.

Advances in Fabrication Materials of Honeycomb Structure Films by the Breath-Figure Method

Creatures in nature possess almost perfect structures and properties, and exhibit harmonization and unification between structure and function. Biomimetics, mimicking nature for engineering solutions, provides a model for the development of functional surfaces with special properties. Recently, honeycomb structure materials have attracted wide attention for both fundamental research and practical applications and have become an increasingly hot research topic. Though progress in the field of breath-figure formation has been reviewed, the advance in the fabrication materials of bio-inspired honeycomb structure films has not been discussed. Here we review the recent progress of honeycomb structure fabrication materials which were prepared by the breath-figure method. The application of breath figures for the generation of all kinds of honeycomb is discussed.

Sensing mechanism of nanofibrous membranes for fluorescent detection of metal ion

We have reported a hexaphenylsilole/polymethyl methacrylate (HPS/PMMA) composite film with a lotus-leaf-like structure shows highly stability and excellent sensitivities for metal ions (Fe3+ and Hg2+) a few years ago. In the above paper, it was considered that the special surface morphology is the important aspects which enhance the stability of the sensor. But it is still a lack of research on the sensing mechanism. In this paper, the sensing mechanism of fiber membrane is continuing to study in detail. The experimental results show that the electron-transfer mechanism is a crucial factor for the fluorescent quenching.

Morphology controllable self-assembly of hierarchical hexaphenylsilole structures and their properties

Morphology controllable hexaphenylsilole hierarchical homo-aggregations have been prepared by the self-assembly method in this paper. Tuning the solvent parameters can significantly affect the morphologies of the resulting HPS aggregations. The solvent properties play an important role in the shape-controlled synthesis of nanostructures. The possible self-assembly mechanism was also discussed. All of the different hierarchical structures aggregated from different solvents show different florescence and different absorption spectra properties, which could be of importance and have potential applications in the fields of optoelectronic functional materials.

Dual high adhesion surface for water in air and for oil underwater

A new type of dual high surface adhesion both in an oil/water/solid system and in a water/air/solid system is reported. A walnutlike cuprous iodide (CuI) microcrystal surface, which is composed of numerous CuI nanocrystals, shows an amphiphobic, highly adhesive surface for water in air and for oil underwater. The maximum adhesive force is about 120.3 ± 1.6 μN in the air for a water droplet and about 23.8 ± 2.1 μN underwater for an oil droplet. These findings will help us to design novel high adhesive materials in two-phase or multiphase mediums.