Surface Texture Research Articles

Hydrophobic surface texture air-liquid phase composite assisted laser processing and tribological properties

In order to improve the surface hydrophobicity and tribological properties of 304 stainless steel, this study used laser processing technology to prepare three types of surface textures (CSA, CM2, CM5) in an air and air–liquid composite environment. By testing the surface quality, wettability and tribological properties of the texture, it was found that the surface quality and interfacial friction control ability of CSA were poor due to the influence of the processing environment. However, due to the air–liquid composite assisted laser preparation, while using the air medium laser processing technology to ensure the texture depth, the scattering effect of bubbles and the influence of negative pressure on the solid–liquid interface during the liquid phase assisted laser processing remove the oxide recast layer and burr on the surface of the sample, and improve the surface quality of the texture, thereby improving the surface friction behavior of the sample. This study promotes the development of surface texture laser processing technology and broadens the application field of 304 stainless steel.

Optimizing Surface Texture Through Ion Induction for High Areal Capacitance and Enhanced Stability in MXene Electrodes

AbstractTo make supercapacitors a viable commercial product, it is necessary to increase the mass loading (ML) of the electrodes. However, current research on high ML MXene electrodes mainly focuses on internal structure optimization, often neglecting the importance of surface texture in the electrodes, which plays a crucial role in mediating interactions between the internal structure and the electrolyte. This study reports on a simple ion‐intercalation process that can reduce charge transfer resistance and improve cycling stability. Through the integration of 3D visualization models and wide‐angle X‐ray scattering techniques, a comprehensive investigation of the electrode's surface structure and MXene flake arrangement is conducted. The results showed that pre‐oriented aggregates induced by ion‐intercalation create a sophisticated surface structure with rich hills and valleys, promoting electrolyte permeation and ion exchange. This work highlights the significance of surface texture in films and electrodes, guiding the design of high‐performance materials.

Finite Element Simulations and Statistical Analysis for the Tribological Design of Mutually Textured Surfaces and Related Experimental Validation

Abstract In the last few decades, micro-texturing has become a widely studied technique to modify the frictional behavior between surfaces in both dry and lubricated regimes. Among all the available techniques, the laser surface texturing appears to be fast, clean, and flexible, and thus a good candidate in realizing surface micro-patterns, also for the improvement of the tribological performance of automotive components when subjected to dry friction. For this reason, in the present work, the tribological response of four different patterns of micro-holes on two contrasting materials, specifically silicon carbide and carbon black have been investigated with a coupled experimental–numerical approach. The static and the dynamic friction coefficients have been extracted from the 25 different combinations of these surface textures including the flat counterparts. Then, the influence of the holes diameter, their density, and the material has been studied thanks to a multivariate linear regression. Specifically, it emerged that, in a dry regime, the most emerging parameter is the micro-holes diameter, for both static and dynamic frictions. Moreover, for both static and dynamic frictions, the material which more influences the effects of patterns to the overall frictional behavior is here the stiffest one. These insights for the design of micro-patterned surfaces with controlled frictional properties could be useful for those applications in which a dry friction regime is present.

Bionic Strategies for Pump Anti-Cavitation: A Comprehensive Review

The cavitation phenomenon presents a significant challenge in pump operation since the losses incurred by cavitation adversely impact pump performance. The many constraints of conventional anti-cavitation techniques have compelled researchers to explore biological processes for innovative alternatives. Consequently, the use of bionanotechnology for anti-cavitation pumping has emerged as a prominent study domain. Despite the extensive publication of publications on biomimetic technology, research concerning the use of anti-cavitation in pumps remains scarce. This review comprehensively summarizes, for the first time, the advancements and applications of bionic structures, bionic surface texture design, and bionic materials in pump anti-cavitation, addressing critical aspects such as blade leading-edge bionic structures, bionic worm shells, microscopic bionic textures, and innovative bionic coatings. Bionic technology may significantly reduce cavitation erosion and improve pump performance by emulating natural biological structures. This research elucidates the creative contributions of biomimetic designs and their anti-cavitation effects, hence boosting the anti-cavitation performance of pumps. This work integrates practical requirements and anticipates future applications of bionic technology in pump anti-cavitation, offering a significant research direction and reference for scholars in this domain.

Sustainable synthesis of silver nanoparticles from Azadirachta indica: antimicrobial, antioxidant and in silico analysis for periodontal treatment.

This study explores potential application of silver nanoparticles (AgNPs) to treat periodontal infection using Azadirachta indica leaf extract. The eco-friendly green synthesis process uses Azadirachta indica as a natural stabilizer and reducer, allowing AgNPs to be formed. Experimental AgNPs were characterized through transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), Zeta potential, ultraviolet-visible spectroscopy (UV-Vis) etc. The antimicrobial, antioxidant potential of AgNPs was tested to identify its efficacy against periodontal infections. AgNPs were found spherical, nanosized (86nm), with negative surface charge (-26.9mV). TEM study depicted clear formation of discrete nanosize particles with smooth surface texture. Results showed strong antibacterial and anti-oxidant action of experimental AgNPs, preventing biofilm growth and bacterial viability. A higher binding affinity was observed between Quercetin and the selected protein, which is implicated in bacterial growth and biofilm formation on teeth. The study suggests that Azadirachta indica derived AgNPs could be a safe, efficacious, and eco-friendly alternative in place of conventional therapies to treat periodontal infection. Future in vivo studies are however warranted.

Corrosion resistance and biocompatibility of magnesium alloy with bioactive glass-reinforced hydrogel composite coatings

Magnesium (Mg) alloy is a promising candidate for biodegradable implants; however, its rapid degradation can create an unstable physiological environment that hampers tissue regeneration. To address this challenge, a polyvinyl alcohol (PVA) hydrogel composite reinforced with bioactive glass (BG) particles was developed as a coating for Mg alloy pellets, which underwent laser surface texturing (LST) and salting-out processes. results demonstrate that these treatments significantly enhance both the adhesiveness and swelling of the hydrogel coating. Notably, electrochemical corrosion assessments reveal a marked improvement in corrosion resistance, with the Mg–B1-L-S specimen exhibiting the highest performance after salting-out treatment. Electrochemical corrosion assessments revealed a significant enhancement in corrosion resistance for Mg alloy with the hydrogel coating, with the Mg–B1-L-S specimen showing superior performance following salting-out treatment. Immersion tests in simulated body fluid (SBF) confirmed the protective effect of the coatings, indicating that the addition of BG particles and salting-out treatment reduced mass loss and maintained pH stability. Biocompatibility evaluations through in vitro viability tests and osteogenic differentiation assays indicate that the Mg–B1-L and Mg–B1-L-S specimens exhibit superior cell activity, surface adhesion, and osteogenic potential. These findings highlight the effectiveness of PVA-BG hydrogel composite coatings in enhancing the corrosion resistance and biocompatibility of Mg alloy implants, positioning this approach as a significant advancement in the development of biodegradable materials for biomedical applications.

A Review on the Effect of Wood Surface Modification on Paint Film Adhesion Properties

Wood surface treatment aims to improve or reduce the surface activity of wood by physical treatment, chemical treatment, biological activation treatment or other methods to achieve the purpose of surface modification. After wood surface modification, the paint film adhesion performance, gluing performance, surface wettability, surface free energy and surface visual properties would be affected. This article aims to explore the effects of different modification methods on the adhesion of wood coating films. Modification of the wood surface significantly improves the adhesion properties of the paint film, thereby extending the service life of the coating. Research showed that physical external force modification improved the hydrophilicity and wettability of wood by changing its surface structure and texture, thus enhancing the adhesion of the coating. Additionally, high-temperature heat treatment modification reduced the risk of coating cracking and peeling by eliminating stress and moisture within the wood. Chemical impregnation modification utilized the different properties of organic and inorganic substances to improve the stability and durability of wood. Organic impregnation effectively filled the wood cell wall and increased its density, while inorganic impregnation enhanced the adhesion of the coating by forming stable chemical bonds. Composite modification methods combined the advantages of the above technologies and significantly improved the comprehensive properties of wood through multiple modification treatments, showing superior adhesion and durability. Comprehensive analysis indicated that selecting the appropriate modification method was key for different wood types and application environments.

Macroscopic perspective on phase transition behavior of natural single-crystal graphite under different pressure environments

Comprehensive understanding of the direct transformation pathway from graphite to diamond under high temperature and high pressure has long been one of the fundamental goals in materials science. Despite considerable experimental and theoretical progress, current experimental studies have mainly focused on the local microstructural characterizations of recovered samples, which has certain limitations for high-temperature and high-pressure products, which often exhibit diversity. Here, we report on the pressure-induced phase transition behavior of natural single-crystal graphite under three distinct pressure-transmitting media from a macroscopic perspective using in situ two-dimensional Raman spectroscopy, scanning electron microscopy, and atomic force microscopy. The surface evolution process of graphite before and after the phase transition is captured, revealing that pressure-induced surface textures can impede the continuity of the phase transition process across the entire single crystal. Our results provide a fresh perspective for studying the phase transition behavior of graphite and greatly deepen our understanding of this behavior, which will be helpful in guiding further high-temperature and high-pressure syntheses of carbon allotropes.

Experimental characterisation and visualisation of a novel two-phase flexible heat transfer device

The importance of passive Flexible Heat Transfer Device (FHTD) in electronic cooling or space applications lies in their ability to provide efficient, reliable, and adaptable thermal management solutions. Heat transfer enhancement studies pertaining to FHTD developed to meet the thermal management demands of futuristic flexible electronic devices are presented in the current work. The possibility of extending the heat transport limit of FHTD beyond 24 W by limiting the maximum operating temperature to 60 °C is discussed. The superior performance of FHTD at varying heat loads from 5 W to 40 W at 45°and 90°bending angles is brought out compared with existing heat transfer devices like Flexible Heat Pipe (FHP) and copper thermal straps. The performance is reported in thermal resistance and equivalent thermal conductivity. A commercial dielectric liquid is used as a working fluid in FHTD to enhance the heat transfer limit employing phase change. The evaporator and condenser sections of the flexible section are made transparent to visualise the boiling and condensation phenomenon. Under steady-state operation at a 45°bending angle, The FHTD demonstrates a minimum thermal resistance of 0.73 K/W and a peak effective thermal conductivity of 8172 W/m K. The heat transfer coefficient ranges from 200 to 700 W/m2 K, consistent with values reported for heat pipes in the literature. Additionally, the study explores the impact of modifying the external surface texture to create more nucleation sites, thereby enhancing the performance of the FHTD. The results show that the laser-textured surface on the heat pipe condenser effectively reduces the onset of nucleate boiling for dielectric fluid by 3.5 °C and decreases the maximum temperature of the evaporator by 4.5 °C. The present work dictates the fundamental baseline for possible design choices of futuristic passive flexible heat transfer devices.

Effect of process temperatures on joining aluminum alloy (AA5052) to polypropylene (PP) by friction lap welding

The joining of aluminum alloy 5052 (AA5052) and polypropylene (PP) by friction lap welding (FLW) was investigated under different process temperature conditions. Welding experiments were conducted at different tool rotational speeds, and the process temperatures were monitored using an infrared camera and thermocouples. The temperature distribution at the cross-section was determined using a validated numerical model. The joint quality was assessed by measuring tensile shear strength and examining the joint morphology. It was found that interfacial temperatures in the range of 156 °C–316 °C were optimal for achieving effective mechanical interlocking, attributed to the appropriate flow of molten PP into the textured aluminum alloy surface. Temperatures below 130 °C resulted in inadequate PP flow, leading to poor joint formation, while temperatures above 316 °C caused over-melting of PP, bubble formation, and approached the PP initial decomposition limit. Raman spectroscopy showed that the process temperatures did not cause significant chemical bonding and that mechanical interlocking was the main contributing joining mechanism. The results showed that dissimilar welding of metals and non-polar polymers can be optimized by the precise monitor and control of the temperature of the process.

Enhanced tribological properties and cyto-biocompatibility of dental Ti6Al4V alloy via laser surface texturing

Currently, the application of titanium-based implants is hindered by challenges such as inadequate wear resistance and limited osseointegration. Surface texturing technique has been recognized as an effective strategy to improve the surface performances of metallic material. The present work adopts a nanosecond laser texturing technique to fabricate micro textures on the titanium substrate. Firstly, the influence of laser parameters on the texture morphology and quality were investigated. Subsequently, both isotropic and anisotropic surface textures were fabricated to examine the impacts of texture form on wettability, tribological behavior, and cell adhesion and proliferation. The obtained results reveal that both the two textures promote the surface wettability of Ti6Al4V alloy towards a hydrophobic direction. Furthermore, the anisotropic micro-groove texture and the isotropic micro-grid texture can reduce the wear rate of titanium alloy by 42.02% and 73.64%, respectively. However, from the perspective of cyto-biocompatibility, the anisotropic micro-groove texture is capable of triggering an excellent cell contact guidance phenomenon, leading to a dramatically accelerated proliferation rate and facilitating the bone tissue growth in a specific direction.

Enhanced Photocatalytic Activity in Photocatalytic Concrete: Synthesis, Characterization, and Comprehensive Performance Assessment of Nano-TiO2-Modified Recycled Aggregates

This study presents an exhaustive exploration into the development and rigorous evaluation of nano-TiO2-modified recycled aggregates (NT@RAs) as an environmentally sustainable substitute for natural aggregates in concrete applications. A methodical framework was devised for the synthesis and thorough characterization of NT@RAs, emphasizing the optimization of nano-TiO2 loading onto the RA surface and within its intricate porous structure. The investigation encompassed three distinct types of recycled aggregates: recycled glass sands (RGSs), recycled clay brick sands (RCBSs), and recycled concrete sands (RCSs). Of particular interest, NT@RGS, with its properties of an inherently smooth surface texture and low water absorption, was found to exert a favorable influence on the rheological behavior of concrete, manifested in reduced yield stress, thereby underscoring the potential for fine-tuning mix designs to enhance workability. As the substitution levels of NT@RGS and NT@RCBS escalated, an initial decrement in compressive strength was discernible, which subsequently reversed to strength restoration at optimized substitution ratios. This phenomenon is attributed to the synergistic interplay among NT@RA components. Remarkably, NT@RA-incorporated concrete demonstrated unparalleled self-cleaning abilities, surpassing the performance of concrete with direct nano-TiO2 powder incorporation. This comprehensive research contributes significantly to the advancement in sustainable, high-performance photocatalytic construction materials within the realm of concrete technology. It underscores the potential for enhancing not only the rheological and mechanical properties but also the environmental responsiveness of concrete through the innovative utilization of NT@RAs.

Palaeobiological and geochemical aspects of reptilian coprolites from a Maastrichtian Deccan volcano-sedimentary intertrappean deposit of central India

Cretaceous-Paleogene coprolite (fossilized faecal matter) records are significant in terms of providing direct palaeobiological evidence (from inclusions) in order to understand the diet of producer animal(s). In the past >150 years, research investigations (in India) have focussed on the Maastrichtian Type-A coprolite morphotype. Consequently, little information is available on the overall assemblage of Indian Maastrichtian vertebrate coprolites in terms of their morphological diversity, chemical composition, biotic-abiotic inclusions in the context of producer linkage(s) and geographic distribution within the Deccan volcano-sedimentary infra- and intertrappean deposits of India. Therefore, we present a detailed record of a coprolite assemblage from the Maastrichtian intertrappean deposits of Lotkheri, central India. This coprolite assemblage comprises five morphotypes based on their geometry, surface, and internal textures. Morphological considerations and biotic inclusions suggest that reptiles were the most likely producers of these ichnofossils. The associated faunal remains of reptiles (mainly chelonians and crocodilians) support this hypothesis. Dentalites or bite traces of Garfish (genus Lepisosteus) observed on the external surface of a few coprolite specimens (studied herein) are a rarity in the global fossil records. The analytical evidence confirm the phosphatic composition of the coprolites with the unique presence of three distinct morphologies (i.e. spherical, rods, and needles) of apatite crystals. Finally, we provide the chemical nature and plausible mechanism of apatite crystal formation via the chemical processes undergoing during the biomineralization of these crystals observed within coprolites.

Pen-based vibrotactile feedback rendering of surface textures under unconstrained acquisition conditions

Haptic rendering of surface textures enhances user immersion of human–computer interaction. However, strict input conditions and measurement methods limit the diversity of rendering algorithms. In this regard, we propose a neural network-based approach for vibrotactile haptic rendering of surface textures under unconstrained acquisition conditions. The method first encodes the interactions based on human perception characteristics, and then utilizes an autoregressive-based model to learn a non-linear mapping between the encoded data and haptic features. The interactions consist of normal forces and sliding velocities, while the haptic features are time–frequency amplitude spectrograms by short-time Fourier transform of the accelerations corresponding to the interactions. Finally, a generative adversarial network is employed to convert the generated time–frequency amplitude spectrograms into the accelerations. The effectiveness of the proposed approach is confirmed through numerical calculations and subjective experiences. This approach enables the rendering of a wide range of vibrotactile data for surface textures under unconstrained acquisition conditions, achieving a high level of haptic realism.

Application of impact-based and laser-based surface severe plastic deformation methods on additively manufactured 316L: Microstructure, tensile and fatigue behaviors

Applying post-processing methods can play a crucial role in addressing defects inherent in the as-built state of additively manufactured materials. This study comprehensively examined the effects of various post-processing techniques, including surface severe plastic deformation (SSPD) methods such as severe shot peening (SSP), ultrasonic shot peening (USP), ultrasonic nanocrystal surface modification (UNSM), and laser shock peening (LSP), combined with stress relieving (SR) on the tensile properties and fatigue behavior of laser powder bed fusion (LB-PBF) stainless steel AISI 316L specimens. Experimental characterization was carried out, focusing on microstructure, porosity, surface texture, hardness, residual stresses, monotonic tensile properties, and rotating bending fatigue behavior. The results demonstrated an excellent combination of enhanced strength and ductility after applying SR and SSPD treatments. Additionally, the post-processing methods significantly improved fatigue behavior by increasing strength, closing subsurface pores, surface layer nanocrystallization and hardening, inducing compressive residual stresses, and modifying the surface texture. Notably, in the high-cycle fatigue regime at the lowest stress amplitude, the SR + UNSM treated specimens exhibited the greatest improvement in fatigue life, followed by SR + USP, SR + SSP, SR + LSP, and SR, when compared to the as-built state.

Enhancing the anti-wear performance of graphene sheets embedded carbon films through interface nanotexture fabricated on the substrate

The effect and mechanism of surface texture on friction have been extensively explored, such as storing the abrasive and reducing the real contact area. However, studying the impact of the interface texture remains crucial, especially as the texture size approaches the nanoscale. In the present work, the silicon substrate with different parameters nanotexture was fabricated using a metal-assisted chemical etching process, and the graphene sheets embedded carbon (GSEC) film was deposited on the nanotextured substrate via a low-energy electron irradiation process to produce the interface nanotextured carbon films. After the addition of the interface nanotexture, the tribological performance of carbon films exhibited significant enhancement, with the degree of improvement being influenced by the parameters of the interface nanotexture. A super-low wear rate was achieved, with a value of 6.54 ± 0.70 × 10−8 mm3/N m. The improved tribological performance is due to the enhancement of film-substrate adhesion strength facilitated by interface nanotexture, and its role in promoting the rapid formation of a stable transfer film on the counter-grinding ball. The carbon film with nanotexture displays a small size of the abrasive particles, which contributes to the stabilization of the friction process.

Ultra-high brightness Micro-LEDs with wafer-scale uniform GaN-on-silicon epilayers

Owing to high pixel density and brightness, gallium nitride (GaN) based micro-light-emitting diodes (Micro-LEDs) are considered revolutionary display technology and have important application prospects in the fields of micro-display and virtual display. However, Micro-LEDs with pixel sizes smaller than 10 μm still encounter technical challenges such as sidewall damage and limited light extraction efficiency, resulting in reduced luminous efficiency and severe brightness non-uniformity. Here, we reported high-brightness green Micro-displays with a 5 μm pixel utilizing high-quality GaN-on-Si epilayers. Four-inch wafer-scale uniform green GaN epilayer is first grown on silicon substrate, which possesses a low dislocation density of 5.25 × 108 cm−2, small wafer bowing of 16.7 μm, and high wavelength uniformity (standard deviation STDEV < 1 nm), scalable to 6-inch sizes. Based on the high-quality GaN epilayers, green Micro-LEDs with 5 μm pixel sizes are designed with vertical non-alignment bonding technology. An atomic sidewall passivation method combined with wet treatment successfully addressed the Micro-LED sidewall damages and steadily produced nano-scale surface textures on the pixel top, which unlocked the internal quantum efficiency of the high-quality green GaN-on-Si epi-wafer. Ultra-high brightness exceeding 107 cd/m2 (nits) is thus achieved in the green Micro-LEDs, marking the highest reported results. Furthermore, integration of Micro-LEDs with Si-based CMOS circuits enables the realization of green Micro-LED displays with resolution up to 1080 × 780, realizing high-definition playback of movies and images. This work lays the foundation for the mass production of high-brightness Micro-LED displays on large-size GaN-on-Si epi-wafers.

Application of 3D Printing to Design and Manufacture Pancreatic Duct Stent and Animal Experiments.

Objective: Postoperative pancreatic fistula (POPF) is a common and challenging complication following pancreaticoduodenectomy (PD), occurring in 2% to 46% of cases. Despite various pancreaticojejunostomy techniques, an effective method to prevent POPF has not been established. This study aimed to develop and evaluate a novel 3D-printed biodegradable pancreatic duct stent to simplify the surgical process of pancreaticojejunostomy, reduce anastomotic complexity, and minimize postoperative complications. Methods: Data from 32 patients undergoing total laparoscopic pancreaticoduodenectomy were utilized. Preoperative CT scans were transformed into 3D reconstructions to guide the design and printing of customized stents using polylactic acid (PLA). The stents were assessed for mechanical integrity, surface texture, and thermal stability. Animal experiments were conducted on 16 mini pigs, with the experimental group receiving the novel stent and the control group receiving traditional silicone stents. Results: The 3D-printed stents demonstrated accurate dimensional replication and mechanical reliability. In the animal experiments, the experimental group showed no significant difference in postoperative complications compared to the control group. At 4 weeks post-surgery, CT scans revealed well-healed anastomoses in both groups, with no significant inflammation or other complications. Histological examination and 3D reconstruction models confirmed good healing and device positioning in the experimental group. Conclusion: The 3D-printed biodegradable pancreatic duct stent offers a promising solution for pancreaticojejunostomy, with comparable safety and efficacy to traditional methods. Further research is needed to validate its clinical application.

Influence of Multiple Repair Welding on Microstructure and Properties of 06Cr19Ni10 Stainless Steel

AbstractRepair welding technology is widely used in the manufacturing and maintenance of rail transit equipment to repair welding defects. However, repair welding induces modifications in joint performance, and it is necessary to study the microstructure evolution behavior to reveal the reasons. In this study, the effects of multiple repair welding on the microstructure, mechanical, and fatigue properties of 06Cr19Ni10 stainless steel samples were studied. The surface texture and fracture morphology analyses of the samples were conducted by optical microscopy (OM), scanning electron microscopy (SEM), and its equipped backscattered electron diffraction (EBSD) technique. The mechanical and fatigue properties of the samples with different repair welding times were further obtained by hardness, tensile, and fatigue tests. The results show an increase in the grain size and the substructure content in the heat-affected zone (HAZ), and the austenite orientation is changed, attributable to multiple repair welding. Multiple heat inputs result in a significant increase in hardness from 165 HV to 185 HV, a noticeable decrease in tensile strength and elongation, and an upward trend in yield strength. Under the constant stress level, the heat input of multiple repair welding causes a decrease in the fatigue life and significantly reduces toughness in the instantaneous fracture zone of the secondary repair sample.

Tunable Topological Wetting State of Water Droplets on Planar Surfaces: Closed-Loop Chemical Heterogeneity by Design.

Understanding droplet wetting on surfaces has broad implications for surface science and engineering. Here, we report a joint theoretical/experimental study of the topological wetting states of water droplets on chemically heterogeneous closed-loop and planar surfaces. Interestingly, we provide both simulation and experimental evidence of biloop or even multiloop transition wetting states of water droplets. Specifically, in our molecular dynamics simulations, we designed surfaces patterned with alternating closed-loop superhydrophilic and hydrophobic nanobands. On these surfaces, we find that the contact shape and contact angle of water nanodroplets can be tailored by changing the shape of the nanobands. Overall, the contact angle of the droplets is dependent on the initial location of the water droplet, the interaction between the water molecules and hydrophobic particles, and the width of the superhydrophilic and hydrophobic nanobands. The wetting-state transition dynamics is also dependent on the nanoband shape. In the biloop or multiloop transition wetting states, the three-phase contact line is not limited to only one loop nanoband but can be located at two or more distinct loops. Guided by the simulation results, the corresponding experiments confirmed the presence of topological wetting states and multiloop wetting states on planar chemically heterogeneous surfaces with closed-loop microbands. Importantly, we provide an explanation of the mechanism of the topological wetting state formation and transition. Our study facilitates a deeper understanding of the droplet-surface interactions and offers an alternative way to tune the droplet shape and contact angle on planar surfaces by engineering chemically heterogeneous surface textures.