Hybrid Surface Research Articles

Designing Organic and Hybrid Surfaces and Devices with Initiated Chemical Vapor Deposition (iCVD).

The initiated chemical vapor deposition (iCVD) technique is an all-dry method for designing organic and hybrid polymers. Unlike methods utilizing liquids or line-of-sight arrival, iCVD provides conformal surface modification over intricate geometries. Uniform, high-purity, and pinhole-free iCVD films can be grown with thicknesses ranging from >15µm to <5nm. The mild conditions permit damage-free growth directly onto flexible substrates, 2D materials, and liquids. Novel iCVD polymer morphologies include nanostructured surfaces, nanoporosity, and shaped particles. The well-established fundamentals of iCVD facilitate the systematic design and optimization of polymers and copolymers. The functional groups provide fine-tuning of surface energy, surface charge, and responsive behavior. Further reactions of the functional groups in the polymers can yield either surface modification, compositional gradients through the layer thickness, or complete chemical conversion of the bulk film. The iCVD polymers are integrated into multilayer device structures as desired for applications in sensing, electronics, optics, electrochemical energy storage, and biotechnology. For these devices, hybrids offer higher values of refractive index and dielectric constant. Multivinyl monomers typically produce ultrasmooth and pinhole-free and mechanically deformable layers and robust interfaces which are especially promising for electronic skins and wearable optoelectronics.

Impact of polypyrrole units (pyr*n; n=3, 5, 7, or 9) on the adsorption and excitation dynamics of enrofloxacin antibiotic interaction with hafnium-doped graphene/boron nitride (Hf@GP/BN) heterostructure: A theoretical perspective

This research work focuses on investigating on influence of pyrrole units (pyr) on the structural stability, reactivity, adsorption potential, bonding variation, and the visible-light interactions of enrofloxacin (xacin) antibiotic with hafnium-doped graphene/boron nitride (Hf@GP_BN) heterostructure within the framework of hybrid exchange-correlation functional and the Monte Carlo molecular simulations. The interaction of enrofloxacin (xacin) with the hybrid surface pyr*n_Hf@GP_BN (where n = 3, 5, 7, or 9) provided insights into the effects of changing the polypyrrole (pyr) chain length on the resulting interactions: xacin_pyr3_Hf@GP_BN, xacin_pyr5_Hf@GP_BN, and xacin_pyr7_Hf@GP_BN respectively to gain more efficient degradation capabilities and the influence of the increase polymer chain. The calculated energy gap decreases due to the increase in LUMO energy experienced upon the addition another of ring, nonetheless when the length of the polypyrrole was further adjusted to seven, the energy gap of the composite increased from 2.184 eV to 2.205 eV which is in the range of semi-conductor to support efficient electron excitation. Results of the molecular dynamic (MD) simulation reveal that while the potential energy of the system decreased for all pyr*n_Hf@GP_BN combinations, the magnitude of the potential energy reduction varied with different pyr chain lengths. Pyr3 exhibited the least reduction of 1310.899 ± 36.119 kcal/mol, followed by 1402.128 ± 38.678 for pyr5, 1511.129 ± 40.494 for pyr7, and 1616.720 ± 43.445 kcal/mol for pyr9, which displayed the most substantial reduction. Longer pyr chains (pyr7 and pyr9) seem to have stronger attractive interactions with enrofloxacin, leading to more significant energy reductions. This indicates that longer pyr chains are more effective in stabilizing the interactions between the antibiotic and the hybrid surface. While the UV-excitation analysis revealed that an increase in the polypyrrole chain length led to a decrease in the wavelength for both the adsorbent and the interactions, decreasing order of exciton binding energy is observed as: 0.602585, 0.606008, and 0.597378 for xacin_pyr3_Hf@GP_BN, xacin_pyr5_Hf@GP_BN, and axacin_pyr7_Hf@GP_BN respectively which is below the 1.9 eV benchmark of efficient materials for photodegradation. The findings could contribute to the broader field of photocatalysis, potentially informing the design of more effective photocatalytic materials. Therefore, research contributes to the development of more efficient methods for antibiotic degradation, with potential applications in environmental remediation.

Enhanced boiling heat transfer on three-dimensional hybrid micropillar array surfaces

Boiling heat transfer is widely used in numerous industrial systems because of its excellent heat dissipation performance. The critical heat flux (CHF) represents the upper limit of efficient heat removal. The most widely applied CHF model is Zuber's hydrodynamic instability model, which posits that the interference between vapor and liquid counterflows results in the CHF. In this paper, a three-dimensional (3D) hybrid micropillar array surface for hindering the liquid–vapor interface is proposed to enhance the CHF and heat transfer coefficient (HTC). The 3D hybrid surface comprises a tall hydrophobic (HB) pillar array surrounded by a short hydrophilic (HP) pillar array. The tall HB pillar array acts as a potential nucleation site for increasing the HTC, and the short HP pillar array acts as a wicking structure for facilitating liquid rewetting. In addition, the height difference between the HB and HP pillar arrays can potentially reduce the interference between liquid and vapor counterflows and increase the CHF. Relative to a plain silica surface, the 3D hybrid surface increases the CHF and HTC by 107% and 360%, respectively. Theoretical modeling suggests that the CHF on the 3D hybrid surface was still limited by pool hydrodynamics.

A review of functionalizing plasma electrolytic oxidation (PEO) coatings on titanium substrates with laser surface treatments

Nowadays, hybrid surface modification techniques are desirable approaches that are widely used to enhance the corrosion and wear behavior and biocompatibility of titanium dental and orthopedic implants. Laser processing is an effective, facile method with high flexibility, accuracy, and controllability for surface modification of titanium implant materials. Plasma electrolytic oxidation (PEO) is a cost-effective and eco-friendly process that can enhance the surface of valve metals like titanium, zirconium, magnesium, and aluminum, as well as non-valve metals such as zinc and niobium. This is achieved by creating thick, hard coatings that are resistant to both corrosion and wear, similar to ceramics. This review focuses on the improvement of anti-corrosion and anti-wear behavior, as well as the biocompatibility of titanium and its alloys through laser surface pre- or post-treatments involving laser surface melting (LSM) and laser surface texturing (LST), combined with PEO technology.

OPTIMIZATION OF DUAL TRANSESTERIFICATION OF JATROPHA SEED OIL TO BIOLUBRICANT USING HYBRIDIZED RESPONSE SURFACE METHODOLOGY (RSM) AND ADAPTIVE NEURO FUZZY INFERENCE SYSTEM (ANFIS)-GENETIC ALGORITHM (GA)

The over-reliance of the industrial and automobile sectors on petroleum-based lubricants, the feedstocks of which pose environmental challenges, has generated the need for sustainable alternatives in order to promote economic development and a sustainable green environment. The study investigated the optimization of process variables for the dual transesterification of jatropha seed oil into a biolubricant using a hybridized response surface methodology-genetic algorithm (RSM-GA) and an adaptive neuro-fuzzy inference system-genetic algorithm (ANFIS-GA). The seed oil was extracted using a Soxhlet extractor and characterized for its physicochemical properties. The catalyst for the reaction was synthesized by the acid modification of clay. The experimental design was created using Design Expert, and process parameters were optimized using RSM-GA and ANFIS-GA. The yield of oil was 56%, and its properties did not impede the catalyst from transesterification without pretreatment. The modified clay effectively converted the jatropha seed oil into a biolubricant. The ANFIS-GA model attained the highest yields (92.36%) under the optimal parameters of 3h reaction time, 120oC reaction temperature, 3% wt catalyst dosage, 5:1 TMP/JSOME molar ratio, and 300rpm agitation speed. Therefore, the incorporation of ANFIS and RSM with GA was more efficient in optimizing and predicting the biolubricant yield.

Recent development of innovative steel fibers for ultra-high-performance concrete (UHPC): A critical review

This paper presents a comprehensive review of recent advancements in innovative high-strength steel fibers for ultra-high-performance concrete (UHPC). Firstly, commercially available ordinary steel fibers for UHPC products are introduced, and the analysis of fiber aspect ratio on the mechanical properties of UHPC follows. Subsequently, the historical development of deformed steel fibers, including hooked, corrugated, twisted, half-hooked, and curvilinear steel fibers for UHPC, is reviewed, accompanied by a discussion of their impact on various properties of UHPC. In response to limitations associated with specific deformed steel fibers in UHPC due to stress concentration, recent development of surface-refined straight steel fibers is presented. The paper further highlights the development of surface-roughened steel fibers through physical and chemical methods aimed at increasing surface roughness and interfacial friction in UHPC, along with an explanation of the benefits of these surface-roughened steel fibers in enhancing both fiber-matrix interfacial bond and tensile performance. Additionally, the adoption of active and inert nanomaterial-based surface coatings on steel fibers for UHPC is explored to intensively reinforce the interfacial transition zone between the fiber and matrix. Hybrid surface refining methods and various chemical treatment techniques for modifying the surface properties of steel fibers in UHPC are reviewed and discussed. Finally, based on the available current database, optimal fiber types as reinforcements for UHPC, in terms of tensile and flexural performances, are suggested.

Universal differential equations for glacier ice flow modelling

Abstract. Geoscientific models are facing increasing challenges to exploit growing datasets coming from remote sensing. Universal differential equations (UDEs), aided by differentiable programming, provide a new scientific modelling paradigm enabling both complex functional inversions to potentially discover new physical laws and data assimilation from heterogeneous and sparse observations. We demonstrate an application of UDEs as a proof of concept to learn the creep component of ice flow, i.e. a nonlinear diffusivity differential equation, of a glacier evolution model. By combining a mechanistic model based on a two-dimensional shallow-ice approximation partial differential equation with an embedded neural network, i.e. a UDE, we can learn parts of an equation as nonlinear functions that then can be translated into mathematical expressions. We implemented this modelling framework as ODINN.jl, a package in the Julia programming language, providing high performance, source-to-source automatic differentiation (AD) and seamless integration with tools and global datasets from the Open Global Glacier Model in Python. We demonstrate this concept for 17 different glaciers around the world, for which we successfully recover a prescribed artificial law describing ice creep variability by solving ∼ 500 000 ordinary differential equations in parallel. Furthermore, we investigate which are the best tools in the scientific machine learning ecosystem in Julia to differentiate and optimize large nonlinear diffusivity UDEs. This study represents a proof of concept for a new modelling framework aiming at discovering empirical laws for large-scale glacier processes, such as the variability in ice creep and basal sliding for ice flow, and new hybrid surface mass balance models.

Numerical Simulation of Dropwise Condensation of Steam over Hybrid Surfaces via New Non-Dimensional Heat Transfer Model

Dropwise condensation (DWC) of steam over hybrid hydrophobic–hydrophilic surfaces is numerically investigated via a phenomenological, Lagrangian model. The full non-dimensionalization of the heat transfer model, needed to determine the droplet growth, allows for generalization of computational results. Hybrid surfaces characterized by recursive geometries are implemented via the introduction of proper boundary conditions. The numerical size distribution of both the large and the small droplet populations, crucial for development of simplified, statistically sound models, is compared with empirical and theoretical correlations. Then, the validation with experimental data involving DWC over an hybrid surface is successfully conducted and the heat flux is enhanced under different operating conditions via hybrid geometry optimization.

Uniformly Hybrid Surface Containing Adjustable Hydrophobic/Hydrophilic Components Obtained by Programmed Strain for Synergistic Anti-Icing.

Sufficient efforts have been put into the design of anti-icing materials to eliminate the icing hazard. Among the currently approved anti-icing concepts, hydrophilic/hydrophobic hybrid anti-icing materials inspired by antifreeze proteins show excellent properties in inhibiting ice nucleation, inhibiting ice crystal growth, and reducing ice adhesion. However, it is still a great challenge to accurately regulate the hydrophilic and hydrophobic hybrid components of the coating surface to clarify the synergistic mechanism. This work proposes a strain-manipulated surface modification strategy, and an anti-icing coating with adjustable hydrophilic/hydrophobic hybrid components prepared by combining chemical vapor deposition and siloxane chemistry is obtained. According to the ice resistance experiment at -15 °C, the performance of anti-icing is closely related to the proportion of hydrophilic and hydrophobic hybrids. The icing delay time and ice adhesion strength of the material with the optimal hydrophilic/hydrophobic components are 280 s and 18.6 kPa, respectively. These unique properties can be attributed to the synergistic effect of hydrophilic and hydrophobic structures on the regulation of interfacial water.

Hybrid surface implants: Influence of residual stress on mechanical behavior, evaluated by finite element analysis and validation by fatigue tests

ObjectivesTo determine the influence of different surface roughness and residual stress of hybrid surface implants on their behavior and mechanical failure. MethodsThree types of implants with different surface roughness were used as specimens: smooth, rough, and hybrid. A diffractometer was used to determine the residual stress of the implants according to their different surface treatment. These results were used as an independent variable in a finite element analysis that compared the three specimens to determine the von Mises stress transferred to the implants and supporting bone and the resulting microdeformations. Flexural strength and fatigue behavior tests were performed to compare the results of the three types of implants. ResultsHigher residual stress values were found for rough surfaces (p < 0.05, Student’s t-test) compared to smooth surfaces, and both types of stress were different for the two types of hybrid implant surfaces. Finite element analysis found different von Mises stress and microdeformation results, both at the level of the implant and the bone, for the three types of implants under study. These results were correlated with the different flexural strength behaviors (lower resistance for hybrids and higher for rough surfaces, p < 0.05) and fatigue behavior (the rough implant had the longest fatigue life, while the hybrid implant exhibited the worst fatigue behavior). SignificanceThe results show a trend toward a less favorable mechanical behavior of the hybrid implants related to the retention of different residual stresses caused by the surface treatment.

Effect of Hybrid Surface Treatment Composed of Plasma Nitriding and Various DLC Coatings on Properties of Stainless Steel SUS316

Effect of Hybrid Surface Treatment Composed of Plasma Nitriding and Various DLC Coatings on Properties of Stainless Steel SUS316

Towards tailored surface topography on electrospun wound dressings for exudate absorption

Since electrospinning can generate micro- to nanometre-scale fibres, it is widely used for fabricating wound dressings. Electrospun scaffolds with defined three-dimensional patterns at the mat surface can be efficiently fabricated using textured collectors that transfer the topography during the manufacturing process. However, the efficacy of surface pattern transfer from the collector to the mat, the correlation between the topography and the absorption capability and the effect of sterilisation on absorption have not yet been analysed. In this study, textured patterns were imprinted over polycaprolactone electrospun mats using textured collectors. The successful transferability of the patterns was quantified through height, hybrid and functional surface topography parameters. Additionally, ethylene oxide, hydrogen peroxide (H2O2) and ultraviolet (UV) sterilisation methods were tested, of which only UV preserved the morphological and functional integrity of the mat. Finally, fibroblasts were used to analyse the cytotoxicity and cellular response of the dressings, verifying their biocompatible nature. This study demonstrates that absorption capacity can be modulated by the surface texture of the wound dressing. The S dq and S dr parameters were identified as key surface characteristics for enhancing absorption capacity and yielded an increase of up to 176.76% compared with the non-textured control, thus revealing the potential of surface functionalisation for increasing exudate absorption.

(Invited) Hybrid Bonding for 3D Applications: Improvements and Limitations

With hybrid bonding pitch reduction, many challenges are arising such as optimized metrology measurement, bonding wave propagation understanding and hybrid surface characterization. By analyzing incoming wafer and how tool setting impacts bonding, overlay values below 110 nm for production wafers can be achieved with 100% electrical yield. Hybrid bonding extends further to IC Logic application or Memory and not only CMOS image sensor. For some of those products, the temperature of usual post bonding thermal annealing (400°C) cannot be applied. Consequently, many studies have been performed on developing low-temperature bonding. To add flexibility to hybrid bonding, new processes such as Surface Activation Bonding (SAB) and Die to Wafer bonding (D2W) have been developed to fit heterogenous integration.

Enhancement of water collection efficiency by optimizing hole size and ratio of hydrophilic-superhydrophobic area on hybrid surfaces

The scarcity of freshwater resources has had a significant impact on human life and wildlife survival. Fog harvesting has emerged as one of the most effective solutions to alleviate water scarcity in arid areas. At present, researchers have focused on optimizing hybrid surface designs to capture fog from the air and convert it into water droplets. Here, we prepared a hybrid surface for fog harvesting by a combination of chemical etching and surface modification with mechanical drilling. By adjusting the hole size and the ratio of hydrophilic-superhydrophobic area of the hybrid surfaces, the water collection efficiency was improved. The results indicated that the hole size affected the critical size of sliding water droplets, and the ratio of hydrophilic-superhydrophobic area affected the water droplet sliding speed and water collection frequency, thereby affecting the water collection efficiency per unit time. Therefore, by matching a specific hole size and ratio of hydrophilic-superhydrophobic area, the water collection volume and mobility of water droplets on the hybrid surfaces reached a dynamic equilibrium, achieving the optimal water collection efficiency. When the hole size was 1.0 mm, and the ratio of hydrophilic-superhydrophobic area was 1:4, the highest water collection rate was 805 mg/cm2/h, and the water collection efficiency was 17.5 %. By optimizing the hole size and the ratio of hydrophilic-superhydrophobic area, the water collection efficiency of the hybrid surface was maximized. This lays a solid foundation for promoting the practical applications of hybrid surfaces for fog harvesting.

Experimental Study on the Condensation Heat Transfer on a Wettability-Interval Grooved Surface

To provide further insight into humid air condensation on hybrid surfaces, an experiment was conducted to visually investigate the condensation process on wettability-interval grooved surfaces, which had hydrophobic ridges and hydrophilic grooves. The droplet dynamic behavior and heat transfer performance of condensation on a wettability-interval grooved surface were explored and compared with four other functional surfaces, including the plain hydrophilic surface, plain hydrophobic surface, hydrophilic grooved surface, and hydrophobic grooved surface. The presence of hydrophobic ridges perpendicular to the groove direction and hydrophilic grooves allowed for the exclusion and easy spreading of droplets, respectively. Compared with the other four functional surfaces, the coupling phenomena during condensation, i.e., the spontaneous suction and directional drainage via hydrophilic grooves, were only found on the wettability-interval grooved surface. These could not only remove condensate quickly but also suppress the formation of the flooded liquid film, which was beneficial to the enhancement of heat transfer performance. It was proven by the experimental results that at subcooling 12 K, the condensation heat flux on the wettability-interval grooved surface reached 1280 W/m2, which was 1.25 times that of the plain hydrophobic surface (1030 W/m2), and 15% higher than that of the hydrophobic grooved surface (1110 W/m2). This indicated that the wettability-interval microgrooves could effectively enhance humid air condensation heat transfer performance.

Hybrid surface wave propagation through the interface of semiconductor and metal waveguide

Hybrid surface wave propagation through the interface of semiconductor and metal waveguides consisting of CuO/Al and ZnO/Al have been investigated by numerical simulation due to their potential applications. COMSOL Multiphysics is used to simulate the waveguides by adjusting model properties. For the comparative study, the propagation constant (γ), normalized phase (β), attenuation constant (α), propagation length (L), total electric and magnetic energy propagated through the CuO-based Al waveguides and ZnO based Al waveguide is discussed. Comparative studies for both modifications were performed from 0 THz to 12 THz. This study employed boundary conditions to have the continuous behavior of the electric field component of hybrid surface waves (exhibits characteristics of both transverse waves and longitudinal waves) at the interface between metal and semiconductor. The ZnO-based modification shows a higher propagation constant (γ) at all frequencies. Similar trends are observed for propagation length (L) and propagation constant (γ). Meanwhile, the attenuation constant (α) of the CuO-based Al waveguide is higher than that of the ZnO-based Al waveguide. An identical trend was perceived for both electrical and magnetic energy. Maximum parameters favour the ZnO-based Al waveguide, which makes it superior to the CuO-based Al waveguide for high-frequency applications.

Fabrication & investigation of properties of hybrid surface composite of magnesium matrix reinforced with aluminum & zinc by friction stir processing

Pure magnesium, despite its advantages, lacks crucial strength and corrosion resistance. With a continuous quest for improved materials and techniques, this study investigates innovative composite materials and the use of FSP for broader industrial applications. The study succeeded in producing this composite with enhanced properties compared to pure magnesium. Notably, the composite exhibited better corrosion resistance, increased strength and hardness. The grain size in the stir zone was significantly smaller, the grain structure was fine without defects, and recrystallized grains were present, resulting in more grain boundaries. Importantly, the properties of this surface composite approached or even surpassed those of some conventionally cast magnesium metal matrix composites. This suggests the potential for using this surface composite and FSP in industrial applications with further process parameter optimization. These findings highlight the promising prospects of surface composites and FSP in replacing traditional methods and bulk composites in specific industries.

Asymmetric Plasmonic Moth-Eye Nanoarrays with Side Opening for Broadband Incident-Angle-Insensitive Antireflection and Absorption.

Plasmonic absorbers with broadband angle-insensitive antireflection have attracted intense interests because of its wide applications in optical devices. Hybrid surfaces with multiple different sub-wavelength array units can provide broadened antireflection, while many of these antireflective surfaces only work for specific angles and require high complexity of nanofabrication. Here, a plasmonic asymmetric nanostructure composed of the moth-eye dielectric nanoarray partially modified with the top Ag nanoshell providing a side opening for broadband incident-angle-insensitive antireflection and absorption, is rationally designed by nanoimprinting lithography and oblique angle deposition. This study illustrates that the plasmonic asymmetric nanostructure not only excites strong plasmonic resonance, but also induces more light entry into the dielectric nanocavity and then enhances the internal scattering, leading to optimized light localization. Hence, the asymmetric nanostructure can effectively enhance light confinement at different incident angles and exhibit better antireflection and the corresponding absorption performance than that of symmetric nanostructure over the visible wavelengths, especially suppressing at least 16.4% lower reflectance in the range of 645-800 nm at normal incidence.Moreover, the reflectance variance of asymmetric nanostructure with the incident angle changing from 5° to 60° is much smaller than that of symmetric nanostructure, making our approach relevant for various applications in photocatalysis, photothermal conversion, and so on.

Directive and coherent thermal emission of hybrid surface plasmon-phonon polaritons in n-GaN gratings of linear and radial shapes

Beaming and coherent thermal emission of the hybrid surface plasmon phonon polaritons (SPPhPs) was numerically and experimentally investigated employing the n-GaN surface relief gratings (SRGs) shaped in a linear and radial geometry. The polariton propagation losses were minimized numerically with the help of a rigorous coupled wave analysis model, while the spatial and temporal quality of selected mode radiation in a normal direction was maximized by fixing the grating period value at 17.5 µm and varying the grating filling factor from 75% to 25%. A set of optimal design linear and radial geometry SRG samples were fabricated in order to validate the emission characteristics of hybrid SPPhPs found by numerical modeling. We demonstrated that both efficient emission and beaming are possible to achieve through the excitation and interference of the same number but opposite sign hybrid polariton modes in n-GaN SRG.

Thermally and mechanically tuned interfaces of magnesium alloys for bioimplant applications

The advent of magnesium (Mg) alloys has ushered in a paradigm shift in the field of biomedical implants, owing to their inherent biodegradability, commendable mechanical strength, and excellent biocompatibility. These unique attributes have given Mg alloys a transformative potential, leading to significant advantages and advancements in patient care. Nevertheless, Mg alloys' rapid degradation upon physiological immersion compromises their mechanical integrity and biocompatibility, challenging their full-scale clinical translation. This review article explores the potential of various thermo-mechanical surface modifications in addressing existing challenges associated with biodegradable Mg alloys. Surface textures with modified dislocation densities, ultrafine twins, stacking fault energy, and wettability characteristics are discussed along with their cellular responses, including protein adhesion, growth factor release, and osteogenic differentiation. To evade the longstanding ‘strength-ductility-corrosion’ trade-off associated with Mg alloys, this review article emphasizes the potential of hybrid surface textures: gradient nano/micro-structured features integrated with chemical modifications. The review concludes by providing future perspectives and research directions on advancements in thermo-mechanically tuned interfaces of magnesium alloys for bioimplant applications.