Search

The preparation of functional surfaces is one of the important methods to enhance the therapeutic performance and safety of medical devices. Currently, the fabrication of functional surface microstructures based on laser processing is widely used in the optimizing medical device surface properties. This paper reviews the current research status of functional microstructures for laser processing of medical implantable and surgical devices in terms of cell function regulation, antimicrobial properties, corrosion resistance, frictional properties, and anti-adhesion, etc. It analyzes the advantages and limitations of laser processing of functional surfaces for medical devices and outlines the development prospects of laser processing technology for functional surfaces for medical devices.

Copyright of Diamond & Abrasives Engineering is the property of Zhengzhou Research Institute for Abrasives & Grinding and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The wettability of metal surfaces is of importance in different practical applications. In the present work, we investigated the role of alumina coatings in the variation of the surface wettability of aluminum alloys by nanosecond laser ablation. The superhydrophilic surface (water contact angle close to 0°) was successfully prepared, and the superhydrophilic surface was transformed into the superhydrophobic surface (water contact angle of about 151.4°) after non-fluorinated N-octyltriethoxysilane (OcTES) treatment. XPS results showed that the Al–OH (–OH) hydrophilic groups generated by coating decomposition occupied the main regions on the surface after laser ablation. After OcTES treatment, the OcTES molecules formed Si–O–Al bonds with the rough surface, which significantly increased the C–C(H) hydrophobic groups of the surface. The superhydrophobic surface showed good self-cleaning, anti-icing and anti-corrosion properties. The fabrication method is fast, non-toxic and environmentally friendly, which makes it potentially useful for engineering applications. [ABSTRACT FROM AUTHOR]

In this study, TiO2 films were deposited via the doctor blade technique on fiber-cement surfaces. Two types of nanoparticles (TiO2-P25 from Degussa and TiO2-PC105 from Tronox) were used to produce films. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) images revealed films with homogeneous and nanoparticulated morphology. The TiO2 PC105 film presented a lower roughness parameter (RMS) in relation to that of the TiO2 P25-based film. Both films exhibited high hydrophilicity when exposed to UV-A radiation (contact angle θ < 6°). The photocatalytic activity of the films was evaluated by standardized methylene blue dye degradation assays under UV-A irradiation (1.0 mW/cm2). The TiO2-PC105 film showed a photonic efficiency of ξ = 0.1%, while for the films obtained with TiO2-P25, ξ = 0.08%. The cement surface modified with the PC105 film was evaluated for antimicrobial activity through the use of multiple pathogens commonly found in hospitals. A considerably high efficiency was measured with visible light. Growth inhibition rates of 99.0% ± 0.2, 99.1% ± 0.2, 99.1% ± 0.2, 97.5% ± 0.5, 98.0% ± 0.5 and 98.0% ± 0.5 were found for Staphylococcus aureus, Klebsiella sp., Escherichia coli, Rhizobium sp., Fusarium sp. and Penicillium sp., respectively. The results show the self-cleaning ability and their potential use for protection, by preventing contamination of the fiber-cement surface and opening new possibilities for the use of this building material. [ABSTRACT FROM AUTHOR]

Aim: The success of dental implants depends on osseointegration can be compromised by well-known related adverse biological processes, such as infection and diabetes. Previously, nanohydroxyapatite-coated titanium surfaces (nHA_DAE) have been shown to contain properties that promote osteogenesis by enhancing osteoblast differentiation. In addition, it was hypothesized to drive angiogenesis in high-glucose microenvironments, mimicking diabetes mellitus (DM). On the other hand, the null hypothesis would be confirmed if no effect was observed in endothelial cells (ECs). Materials and methods: Titanium discs presenting the differential surfaces were previously incubated in an FBS-free cell culture medium for up to 24 h, which was, thereafter, supplemented with 30.5 mM of glucose to expose human umbilical vein endothelial cells (HUVECs, ECs) for 72 h. They were then harvested, and the sample was processed to provide molecular activity of specific genes related to EC survival and activity by using qPCR, and the conditioned medium by ECs was used to evaluate the activity of matrix metalloproteinases (MMPs). Results: Our data guaranteed better performance of this nanotechnology-involved titanium surface to this end once the adhesion and survival characteristics were ameliorated by promoting a higher involvement of β1-Integrin (~1.5-fold changes), Focal Adhesion Kinases (FAK; ~1.5-fold changes) and SRC (~2-fold changes) genes. This signaling pathway culminated with the cofilin involvement (~1.5-fold changes), which guaranteed cytoskeleton rearrangement. Furthermore, nHA_DAE triggered signaling that was able to drive the proliferation of endothelial cells once the cyclin-dependent kinase gene was higher in response to it, while the P15 gene was significantly down-regulated with an impact on the statement of angiogenesis. Conclusions: Altogether, our data show that a nanohydroxyapatite-coated titanium surface ameliorates the EC performance in a high-glucose model in vitro, suggesting its potential application in DM patients. [ABSTRACT FROM AUTHOR]

Magnetically responsive microstructured functional surface (MRMFS), capable of dynamically and reversibly switching the surface topography under magnetic actuation, provides a wireless, noninvasive, and instantaneous way to accurately control the microscale engineered surface. In the last decade, many studies have been conducted to design and optimize MRMFSs for diverse applications, and significant progress has been accomplished. This review comprehensively presents recent advancements and the potential prospects in MRMFSs. We first classify MRMFSs into one-dimensional linear array MRMFSs, two-dimensional planar array MRMFSs, and dynamic self-assembly MRMFSs based on their morphology. Subsequently, an overview of three deformation mechanisms, including magnetically actuated bending deformation, magnetically driven rotational deformation, and magnetically induced self-assembly deformation, are provided. Four main fabrication strategies employed to create MRMFSs are summarized, including replica molding, magnetization-induced self-assembly, laser cutting, and ferrofluid-infused method. Furthermore, the applications of MRMFS in droplet manipulation, solid transport, information encryption, light manipulation, triboelectric nanogenerators, and soft robotics are presented. Finally, the challenges that limit the practical applications of MRMFSs are discussed, and the future development of MRMFSs is proposed.

Hybridization of surface‐bound DNA with complementary strands is the basis of many biotechnological applications. Herein, the structure of interfacial coatings between substrate and bound DNA is a crucial element for hybridization behavior. Herein, three reactive surfaces for constructing DNA‐sensing platforms, namely, plain gold films on silicon, poly(bisphenolA‐co‐epichlorohydrin) (PBAG) surfaces with a brush‐like bilayer structure, and dibenzocyclooctyne monolayers (both on glass), are compared. Fluorescence imaging is employed to survey the effect of coating structure and conformation on hybridization performance. To better understand the interfacial structural properties and chemistry of the coated films, atomic force microscopy, water contact angle measurements, and X‐ray photoelectron spectroscopy are employed to characterize the surface morphology. DNA probe microarrays are created on the different platforms via microchannel cantilever spotting, and their performance for hybridizing with the DNA counterparts is assessed. While all three platforms work reliable for DNA detection, a protein‐binding assay reveals that PBAG surfaces offer the highest hybridization efficiency among these approaches. The results of the present work have significant implications for comprehension of the interactions between the DNA hybridization efficiency and the physico‐chemical properties of surface coatings and can inform the fabrication of DNA sensors.

Designing surfaces with controllable wettability and exploring methodologies for manipulating liquid motion on solid surfaces is an important research challenge. The impact on various interdisciplinary applications, ranging from self‐cleaning technology to the handling of droplets on Lab‐on‐a‐Chip self‐diagnostic devices, is expected to be significant. In this work, it is studied how the combined action of electric fields and pneumatic actuation can be used to achieve wetting transitions from states where droplets stick to surfaces, to states where droplets slide easily with low friction. The manipulation of water droplets on air‐permeable porous surfaces using both electric fields (electrowetting) and air‐pressure is investigated. The control over droplet mobility is achieved by tuning the solid‐liquid adhesion upon voltage application, in order to pin the droplet; de‐pinning is achieved by air pressure application through surface pores. This way low energy consumption and efficient switching between extreme wetting states and droplet mobility are realized. [ABSTRACT FROM AUTHOR]

Abstract Designing surfaces with controllable wettability and exploring methodologies for manipulating liquid motion on solid surfaces is an important research challenge. The impact on various interdisciplinary applications, ranging from self‐cleaning technology to the handling of droplets on Lab‐on‐a‐Chip self‐diagnostic devices, is expected to be significant. In this work, it is studied how the combined action of electric fields and pneumatic actuation can be used to achieve wetting transitions from states where droplets stick to surfaces, to states where droplets slide easily with low friction. The manipulation of water droplets on air‐permeable porous surfaces using both electric fields (electrowetting) and air‐pressure is investigated. The control over droplet mobility is achieved by tuning the solid‐liquid adhesion upon voltage application, in order to pin the droplet; de‐pinning is achieved by air pressure application through surface pores. This way low energy consumption and efficient switching between extreme wetting states and droplet mobility are realized.

As a laser technology, the femtosecond laser is used in biomedical fields due to its excellent performance—its ultrashort pulses, high instantaneous power, and high precision. As a surface treatment process, the femtosecond laser can prepare different shapes on metal surfaces to enhance the material's properties, such as its wear resistance, wetting, biocompatibility, etc. Laser-induced periodic surface structures (LIPSSs) are a common phenomenon that can be observed on almost any material after irradiation by a linearly polarized laser. In this paper, the current research state of LIPSSs in the field of biomedicine is reviewed. The influence of laser parameters (such as laser energy, pulse number, polarization state, and pulse duration) on the generation of LIPSSs is discussed. In this paper, the applications of LIPSSs by femtosecond laser modification for various purposes, such as in functional surfaces, the control of surface wettability, the surface colonization of cells, and the improvement of tribological properties of surfaces, are reviewed. [ABSTRACT FROM AUTHOR]

• Studies on functional molecule surface segregation in electrospinning are reviewed. • Design and regulation methods of surface segregation are illustrated. • Characterization methods revealing the surface segregation extent are summarized. • Prevalent applications of surface segregation electrospun fibers are discussed. Electrospinning has garnered significant attention for fabricating functional composite fibers. Recently, surface segregation exhibits great potential in shaping functional surface of fibers due to the ability to impart surface compositions different from those in the bulk phase. Moreover, the segregation behavior could be effectively regulated by altering the components' properties and the process designs, generating various functional composite electrospun fibers with controllable morphologies and superior performance. Despite the ongoing development and various applications of surface segregation electrospun fibers, surface segregation engineering in electrospinning has not been reviewed by far. To address this gap, this review presents the state-of-the-art developments of the functional molecules surface segregation engineering in electrospinning. Firstly, surface segregation phenomenon and the combination with electrospinning is presented. Secondary, process design and regulation methods of surface segregation during the whole electrospinning process are illustrated. Thirdly, characterization methods revealing the occurrence and extent of the surface segregation are comprehensively summarized. Finally, application of surface segregation electrospun fibers in prevalent fields such as gas sensing, separation and purification, superhydrophobization, anti-bacteria and biocompatibility improvement is discussed. We also highlight the challenges and further perspectives of the surface segregation engineering in electrospinning. This review aims to provide a comprehensive understanding and serve as a guide for future research and innovation in the design and application of functional molecules' surface segregation in electrospun fibers. [ABSTRACT FROM AUTHOR]

Freeform surfaces including both the aspherical and prismatic concave/convex have been widely utilized in optical, electronical, and biomedical areas. Most recently, it is reported that grinding with structured wheels provides new possibility to generate patterns on hard and brittle materials. This paper reports the latest research progress on micro-grooving glass ceramic using laser structured diamond grinding wheels. A nanosecond pulse laser is firstly integrated into an ultra-precision machine tool and used for the in-line conditioning of super abrasive grinding wheels, i.e., truing, dressing, and profiling/texturing. Meanwhile, an offset compensation method, considering the shifting depth of focus (DoF) at different laser irradiation positions, is proposed to accurately generate various profiles on the periphery of the grinding wheels. Three types of patterns (riblets, grooves, and pillars) are successfully fabricated on the ceramic substrate using the laser textured grinding wheels. The results indicate that the integrated laser system offers high flexibility and accuracy in shaping super abrasive grinding wheels, and the grinding using textured grinding wheels provides a promising solution to generate functional microstructures on hard and brittle materials. [ABSTRACT FROM AUTHOR]

Aim: The success of dental implants depends on osseointegration can be compromised by well-known related adverse biological processes, such as infection and diabetes. Previously, nanohydroxyapatite-coated titanium surfaces (nHA_DAE) have been shown to contain properties that promote osteogenesis by enhancing osteoblast differentiation. In addition, it was hypothesized to drive angiogenesis in high-glucose microenvironments, mimicking diabetes mellitus (DM). On the other hand, the null hypothesis would be confirmed if no effect was observed in endothelial cells (ECs). Materials and methods: Titanium discs presenting the differential surfaces were previously incubated in an FBS-free cell culture medium for up to 24 h, which was, thereafter, supplemented with 30.5 mM of glucose to expose human umbilical vein endothelial cells (HUVECs, ECs) for 72 h. They were then harvested, and the sample was processed to provide molecular activity of specific genes related to EC survival and activity by using qPCR, and the conditioned medium by ECs was used to evaluate the activity of matrix metalloproteinases (MMPs). Results: Our data guaranteed better performance of this nanotechnology-involved titanium surface to this end once the adhesion and survival characteristics were ameliorated by promoting a higher involvement of β1-Integrin (~1.5-fold changes), Focal Adhesion Kinases (FAK; ~1.5-fold changes) and SRC (~2-fold changes) genes. This signaling pathway culminated with the cofilin involvement (~1.5-fold changes), which guaranteed cytoskeleton rearrangement. Furthermore, nHA_DAE triggered signaling that was able to drive the proliferation of endothelial cells once the cyclin-dependent kinase gene was higher in response to it, while the P15 gene was significantly down-regulated with an impact on the statement of angiogenesis. Conclusions: Altogether, our data show that a nanohydroxyapatite-coated titanium surface ameliorates the EC performance in a high-glucose model in vitro, suggesting its potential application in DM patients.

Bioelectronics, the merging of biology and electronics, can monitor and modulate biological behaviors across length and time scales with unprecedented capability. Current bioelectronics research largely focuses on devices' mechanical properties and electronic designs. However, the thermofluidic control is often overlooked, which is noteworthy given the discipline's importance in almost all bioelectronics processes. It is believed that integrating thermofluidic designs into bioelectronics is essential to align device precision with the complexity of biofluids and biological structures. This perspective serves as a mini roadmap for researchers in both fields to introduce key principles, applications, and challenges in both bioelectronics and thermofluids domains. Important interdisciplinary opportunities for the development of future healthcare devices and precise bioelectronics will also be discussed., (© 2023 The Authors. Advanced Healthcare Materials published by Wiley‐VCH GmbH.)

Flow boiling is one of the most effective mechanisms in heat transfer thanks to the latent heat of vaporization. Surface modifications such as mixed-wettability have a considerable effect on the boiling heat transfer performance in terms of enhancement in boiling heat transfer as well as critical heat flux. This study introduces a new method of fabrication of biphilic surfaces, where C4F8 (Octafluorocyclobutane) islands are surrounded by silicon. Two different biphilic surfaces were fabricated and compared with the entirely uniform hydrophobic surface taken as a reference,. Each of the biphilic surfaces has three different sections, namely inlet, middle and outlet regions. The first region is mainly hydrophobic (inlet), while the third region is mainly hydrophilic (outlet). The heat transfer coefficients were obtained at different heat fluxes. Compared to the entirely uniform hydrophobic surface, the results show that biphilic surfaces enhance the boiling heat transfer performance by up to 50%. The visualization results revealed that the biphilic surfaces lead to more nucleation sites in the bubbly flow regime and break up the elongated bubbles in the slug flow regime.

The study of spectral signatures of various elements has been enabled with the ability to diffract light using optical gratings, coupled with the ability to control light using lenses and mirrors. As technological devices seek to become more compact while maintaining or increasing operational efficiency, integration of functions becomes necessary to reduce the overall component count. However, due to the lack of axial flexibility, integrated microstructures on complex forms have shown to be challenging to manufacture. Thus, the need for fabrication techniques to be able to produce such microstructures on non-planar surfaces arises. The Continuous Rotating Freeform Shaping (CRFS) algorithm proposed in this paper utilizes the axial flexibility and precision of Ultra-Precision Machining (UPM) to directly fabricate optical quality blazed gratings on complex profiles which can directly be used as mirrors or molds. The developed algorithm not only maintains the tool along the primary profile of the optical surface, but also the rake angle of the tool at every point along the surface for a constant cutting mechanism. This is coupled with a rotation of the tool to maintain the blazed angle across the surface, optimizing the surface for the efficiency of the grating for a specific wavelength. In this paper, the developed algorithm is presented with experimental verifications of the generation of blazed gratings on a high curvature spherical surface and a freeform tri-axial ellipsoidal surface, followed by the corresponding analysis. • Blazed gratings can now be done on challenging freeform surfaces by 5-axis Ultra-precision machining. • The CFRS algorithm deterministically controls the grating process and maintains the rake of the tool along the surface. • The shift in the point locale to maintain rake angle is translationally compensated by the linear axes. • Successfully machined blazed gratings on highly curved ellipsoidal surface using the CFRS algorithm. • Deterministic nature of the process allows for repeatability with relative efficiency. [ABSTRACT FROM AUTHOR]

The recent developments in additive manufacturing (AM) are providing unprecedented opportunities in various fields, including the fabrication of advanced materials for tribological applications. The present work describes the results of an exploratory study focused on the analysis of 17-4 PH steel surfaces obtained using selective laser melting (SLM). In particular, the study includes the analysis of baseline (as-produced) and textured steel surfaces. Surface texturing comprises hexagonal prism structures (with or without dimples) arranged in a honeycomb pattern with 50 µm or 100 µm gap spacing. Starting from the minimum printing size enabled by the 3D printing platform, various textures are prepared by scaling up the characteristic dimensions of the prisms up to 500%. The obtained surface patterns are characterized (qualitatively and quantitatively) using a non-contact computerized numerical control (CNC) measuring system. The coefficient of friction (COF) was investigated using a Ball-on-Disk configuration using bearing steel balls as counterparts. For a fixed sliding speed, different contact loads and sliding radii were considered, while the tests were carried out in either dry or lubricant-impregnated conditions. The results of wear tests in both dry and lubricated conditions indicated that the baseline samples are provided with lower COF compared to the textured ones. For the latter, neither the gap spacing nor the presence of dimples led to significant variations in the COF. However, in lubricated conditions, the values of the COF for baseline and textured surfaces were closer and much smaller. In particular, the results provide clear indications regarding reducing the gap between prisms, which had a beneficial effect on the COF in lubricated conditions. Similarly, sensitivity to dimples was quite remarkable, with a reduction in the COF of about 30% when the larger gap spacing between the prisms was used. [ABSTRACT FROM AUTHOR]

The high specific surface area and electrical conductivity of new 2D metal carbide MXenes make them become a suitable candidate as sensor platform of the gas sensor. Herein, density functional theory (DFT) is implemented to investigate the adsorption of the SF6 decomposed gases (SOF2, SO2, and H2S) on Ti3C2O2, Ti3C2F2, and Ti3C2(OH)2. Modification of the surface of Ti3C2O2 and Ti3C2F2 by O and F point vacancy, respectively, is then performed to improve the adsorption performance. The band structure, charge density differences, electron localization function (ELF), and projected density of states (PDOS) are investigated to study the adsorption mechanism. The results indicate that as compared with the weak adsorption on pristine Ti3C2O2 and Ti3C2F2, the SOF2, SO2, and H2S gas molecules tend to be chemisorbed on Ti3C2O2 and Ti3C2F2 with point vacancy with high adsorption energies. Furthermore, the study of electronic properties suggests that all adsorption systems show high electronic conductivity and the exposed Ti atoms by point defect mainly contribute to the formation of ionic bond with high adsorption energy. Thus, the present results show that Ti3C2O2 and Ti3C2F2 with point vacancy are feasible novel sensing materials to detect SF6 decomposed species with high sensitivity and low electronic noise. The sensitive detection capability of SO2 is particularly noticeable. [ABSTRACT FROM AUTHOR]

Directional droplet transport on smart surfaces with superwettabilities arouse extensive attentions from both the scientific community and industry due to the exciting applications in healthcare, environmental protection, and energy harvesting. The past decades have witnessed the progress and achievements in mechanism disclosure, device preparation, and applied investigation. Herein, various droplet transport schemes are summarized, such as electrohydrodynamic strategy, self‐propelled droplet on anisotropic surfaces, gravity driven droplet on slippery lubricant impregnated porous surfaces (SLIPS), and other engineering strategies. Accordingly, the basic mechanism of droplet manipulation, devices configuration, and key features are presented. The recent cutting‐edge applications of directional droplet transport, including digital microfluidics, electric energy harvesting, fag/water collection, and oil‐water separation are also reviewed. At the end, current challenges and future perspectives in this field are discussed. [ABSTRACT FROM AUTHOR]

In this work, we present an exceptionally high heat transfer coefficient (HTC) and critical heat flux (CHF) achieved by graphene nanoplatelets (GNPs) and copper composite coatings with tunable surface properties. These coatings were created by a combination of powder metallurgy and manufacturing processes including ball milling, sintering, electrodeposition, and salt-patterning. We demonstrated correlations between various coating processes, resultant surface morphologies, properties, and improved boiling mechanism. Electrodeposition of GNP and copper particles led to formation of tall ridge-like structures and valleys to contain the boiling fluid in between. Higher CHF achieved for these coatings was attributed to the microlayer evaporation. It was observed that ball milling of GNP and copper particles prior to their sinter-coating enhanced their surface roughness that resulted in very high HTC, nearly 5.4 times higher than plain copper surfaces. Additional salt-patterning along with sinter-coating yielded interconnected porous networks with high nucleating activity that rendered record-breaking HTC of 1,314°kW/m2-°C. Combination of these coating processes can be adopted to tailor the surfaces and achieve better boiling performance. Novel techniques developed in this work can be applied to a variety of thermal engineering applications.

Hydrophobic surfaces require finely tuned process chains due to the scale, complexity, and patterning methods. For this purpose, vat photopolymerization (VPP) additive manufacturing is a promising method for surface generation; however, together with the fabrication process, the design phase needs to be optimized to achieve the desired surface property. This work presents the influence of the design features of hydrophobic surfaces through multiple studies on simple pillar structures, intrinsic single-unit geometries, and surface deposition on complex substrates. The results showed that depending on the dimensions of single pillar dimensions, wetting properties can extend between the contact angles (CA) of 83°-115.11°. The hydrophobicity was further increased by applying a re-entrant structure, reaching the CA of 115.24°. The surface deposition on the complex substrates significantly increased water droplet adhesion, preventing it from rolling off, which can be beneficial for manifold device protection from the hazardous influence of the environment. In addition, the influence of the surface on the acoustic properties was examined, which showed that the pattern application in the real-life device does not have a detrimental effect on the intrinsic functionality. This study showed that the design phase should be an essential part of the VPP process chain as it significantly influences the wetting properties of the surfaces., (Copyright 2023, Mary Ann Liebert, Inc., publishers.)

In nature, surfaces are evolutionarily designed to allow adaptation of species to their environments. Insects make extensive use of interfacial phenomena because of their small size and thus, large surface‐area‐to‐volume ratio. This enables them to walk on different terrains, dive, swim, and adhere to surfaces in air and underwater. Moreover, they toggle between different interfaces, move in confined spaces, and overcome a wide range of obstacles. This progress report summarizes emerging directions in the field of bioinspired robotics with an emphasis on micro and nanoscale dynamic interactions. It is envisioned that interfacial phenomena will allow to miniaturize robots and increase the complexity of their operation. The key to success is the combination of functional surfaces, structural design and multiple modes of locomotion. For this to be realized, however, new paradigms are needed in terms of materials, fabrication, energy consumption, and actuation. This report discusses the development of small robots inspired by water striders, the bell spider, the leaf and ladybird beetles, backswimmers and cockroaches, among many others. It also discusses small soft robots inspired by roundworms, larvae, and parasites. From a broader perspective, fabrication of many small robots will enable to study collective effects and self‐assembly, group behavior and swarming. [ABSTRACT FROM AUTHOR]

Fog formation decreases light transmission of optically clear materials. A promising approach to address this problem is to control the wetting properties of the material at extremes states, which requires imparting micro and nano morphology features on the surface. However, such features may affect the optical properties of the surface. In this work, superhydrophobic and superhydrophilic surfaces, with different morphology characteristics ranging from nanoscale to hierarchical micro‐nanoscale are fabricated and evaluated in order to investigate which wetting extreme and surface morphology is more suitable to preserve the light‐transmitting properties and exhibit antifogging functionalities. The performance of the aforementioned surfaces is compared for the first time in two different testing modes: under intense fog flow and no surface cooling, and under no‐flow and surface cooling, which enhances dew condensation on the surfaces. It is demonstrated that superhydrophilic surfaces with nanoscale morphology maintain their optical transmittance under fog flow for more than 20 min. This duration is one of the longest reported in the literature revealing the long‐term antifogging functionality of the proposed surfaces. Finally, by tailoring the morphology and the surface wetting properties, an optically switching surface (initially "milky" which becomes "clear") when exposed to humidity is demonstrated. [ABSTRACT FROM AUTHOR]

In microwave antenna applications, continuum structures usually support attached functional surfaces to realize some specific electromagnetic performance. Topology optimization of continuum supporting structures with functional surfaces is a challenge for microwave antenna applications. By introducing the concept of aperture field distribution into the design domain, a weighting approach for the topology optimization of continuum supporting structures with functional surfaces is presented based on the SIMP model. With the weighting aperture field distribution, the objective function of compliance in the previous SIMP method is changed to a weighted compliance. By selecting an optimized control factor, a different truss topology structure with several components from the previous method is clearly obtained. The effectiveness of the proposed method is validated through three typical applications: array antennas, reflector antennas, and conformal antennas with planar and curved functional surfaces. [ABSTRACT FROM AUTHOR]

Goal: Tread patterns are widely used to increase traction on different substrates, with the tread scale, geometry and material being tailored to the application. This work explores the efficacy of using macro-scale tread patterns for a medical application involving a colon substrate – renowned for its low friction characteristics. Methods: Current literature was first summarized before an experimental approach was used, based on a custom test rig with ex vivo porcine colon, to assess different macro-scale tread patterns. Performance was based on increasing traction while avoiding significant trauma. Repeated testing (n = 16) was used to obtain robust results. Results: A macro-scale tread pattern can increase the traction coefficient significantly, with a static traction coefficient of 0.74 ± 0.22 and a dynamic traction coefficient of 0.35 ± 0.04 compared to a smooth (on the macro-scale) Control (0.132 ± 0.055 and 0.054 ± 0.015, respectively). Decreasing the scale and spacing between the tread features reduced apparent trauma but also reduced the traction coefficient. Conclusion: Significant traction can be achieved on colon tissue using a macro-scale tread but a compromise between traction (large feature sizes) and trauma (small feature sizes) may have to be made. Significance: This work provides greater insight into the complex frictional mechanisms of the intestine and gives suggestions for developing functional tread surfaces for a wide range of clinical applications. [ABSTRACT FROM AUTHOR]

Metal additive manufacturing is a major field of study and innovation. In almost every industry, a lot of effort goes into modelizing and optimizing designs in order to minimize global mass. In this context, despite all efforts, metal additive manufacturing, especially SLM, still produces parts generally considered as raw parts with some surfaces still needing to be machined in order to obtain the required geometrical quality. Despite sometimes, great complexity and cost, the machining stage is never taken into account in the design process, especially during the topological optimization approach. This paper proposes a new design for the additive manufacturing method in order to optimize the design stage and takes into account topological optimization machining as well as geometrical and mechanical constraints. The machining constraints are initially integrated as forces and functional surfaces, but also as the result of a topological optimization loop, in order to find the best possible mounting solution for machining. It is shown on a typical aeronautic part that machining forces may be indeed the greatest forces during the part's lifetime. Using two different topological optimization software, i.e. Inspire and Abaqus Tosca, the paper illustrates that it is possible to take into account most of the machining constraints to only slightly modify the initial design and thus simplify the machining stage and reduce cost and possible failure during machining. [ABSTRACT FROM AUTHOR]

Drug resistance to bacteria becomes an emerging intractable problem, therefore, developing novel antibacterial agents has become urgently needed. Herein, a bio-inspired design strategy was adopted to synthesize a series of beetle-like macromolecule of multiple quaternary ammonium salts (QASs), which was designed with different cationic charge densities and numbers of hexadecane chains by adjusting their different quaternization degree (QD). It was found that the fabricated fabric surface with them exhibited controllable and outstanding antibacterial and bacterially anti-adhesive properties. More importantly, the antibacterial efficiency was demonstrated to be enhanced with the increasing of QD, and related to the zeta potential, and surface tension. Additionally, the proposed bacterially anti-adhesive model of action revealed the "resisting effect" of hydration layer which greatly resisted the adhesion of bacteria. Unlabelled Image • A bio-inspired beetle-like multiple QAS was prepared; • Excellent antibacterial and anti-adhesive properties; • "resisting effect" of hydration layer was revealed. [ABSTRACT FROM AUTHOR]

In the past few decades, the self‐healing surface materials with durable mechanical, functional, and structural properties have attracted enormous research interests, which exhibit great potential in energy conversion devices, sensors, electronic skins, superhydrophobic fabrics, medical/biological hydrogel, and a protective coating. Despite the remarkable progresses achieved in the self‐healing surface, the systematic and overall reviews that focus on self‐healing surface materials are still lacking and in urgent need. Herein, the recent advances in the development of self‐healing surface materials are summarized. The surface damage forms that composed of cracks, scratches, punctures, and surface wear, are systematically reviewed. The self‐healing mechanism and methods at interface are then introduced to briefly explain the basic design principle. The recent developments of functional surfaces including superhydrophobic, oleophobic, antifogging, anti‐icing, antibiofouling, and anticorrosion surfaces with self‐healing functions are further discussed. Finally, the contemporary challenges, and the future perspectives that motivate are proposed to create more innovative self‐healing materials for diverse fields. [ABSTRACT FROM AUTHOR]

Surface microstructures can provide various functionalities, and wettability is a typical surface property that can be controlled by the surface textures. This study attempted to fabricate hierarchical microstructures through ultrasonic-assisted face milling (UAFM) to change the surface functionality by specifically focusing on the wettability. The fabrication involved the use of an ultrasonic generating spindle and a self-designed diamond tool. The locus of the tip of the diamond tool was computed based on the equation of motion, and the micro- and macrostructures are illustrated in this paper. The structures were confirmed through observations using a white-light interferometer. The wettability on six zones of the processed area was measured, and the results indicated that the central zone of the UAFM surface became hydrophobic, whereas the edge zone became hydrophilic. [ABSTRACT FROM AUTHOR]

Wettability is a fundamental property of solid surfaces that can be effectively manipulated by altering the surface chemistry or microstructural morphology. Functional surfaces with reversible wettability conversion are of interest due to their unique properties and wide range of potential applications. This paper presents a systematic and comprehensive review of the latest research progress in the field of reversible wettability conversion. The background and significance of surface wettability research are introduced, the basic models and related theories of wettability are summarized, and the mechanism of wettability conversion is discussed. Moreover, the main stimulus modalities, including physical and chemical stimuli, that respond to wettability conversion are discussed. Furthermore, specific applications of wettability reversible conversion surfaces in the areas of anti-icing/de-icing, directional transportation, signal detection, droplet manipulation, droplet storage, microdroplet response, oil-water separation are presented. Finally, the challenges and future prospects of wettability reversible conversion functional surfaces are discussed. The review provides a reasonable reference for the construction of wettability reversible regulatory mechanisms and responsive surfaces, and provides useful insights into the application and development of wettability reversible conversion surfaces. • Comprehensive review of research advances in reversibly switchable wettability • The background and significance of surface wettability research are introduced. • The basic models and related theories of wettability are summarized. • The main stimulus modalities that respond to wettability switching are discussed. • Challenges and future prospects for reversible wettability switching are discussed. [ABSTRACT FROM AUTHOR]

Roll-to-roll nanoimprint lithography (RTR-NIL) is a low-cost and continuous fabrication process for large-area functional films. However, the partial ultraviolet (UV) resin filling obstructs the ongoing production process. This study incorporates UV resin filling process into the nanopillars and nanopores by using RTR-NIL. A multiphase numerical model with a sliding mesh method is proposed in this study to show the actual phenomena of imprint mold rotation and feeding of UV resin on the polyethylene terephthalate (PET) substrate. The implementation of UV resin filling under environmental conditions was performed by utilizing the open-channel (OC) boundary conditions. The numerical model was solved by using the explicit volume of fluid (VOF) scheme to compute the filling on each node of the computational domain. The effects of different processing parameters were investigated through the proposed numerical model such as imprinting speed (IS), contact angles (CAs), viscosity, initial thickness of the PET, and supporting roll diameter. A good agreement was found between numerical simulations and experimental results. The proposed numerical model gives better insights of the filling process for the mass production of functional surfaces with nanopillars and nanopores patterns for different applications on an industrial scale.

By using sandpaper of different grit, we have scratched up smooth sheets of acrylic to cover their surfaces with disordered but near parallel micro-grooves. This procedure allowed us to transform the acrylic surface into a functional surface; measuring the capillary rise of silicone oil up to an average height h¯, we found that h¯ evolves as a power law of the form h¯∼tn, where t is the elapsed time from the start of the flow and n takes the values 0.40 or 0.50, depending on the different inclinations of the sheets. Such behavior can be understood alluding to the theoretical predictions for the capillary rise in very tight, open capillary wedges. We also explore other functionalities of such surfaces, as the loss of mass of water sessile droplets on them and the generic role of worn surfaces, in the short survival time of SARS-CoV-2, the virus that causes COVID-19.

The recent developments in additive manufacturing (AM) are providing unprecedented opportunities in various fields, including the fabrication of advanced materials for tribological applications. The present work describes the results of an exploratory study focused on the analysis of 17-4 PH steel surfaces obtained using selective laser melting (SLM). In particular, the study includes the analysis of baseline (as-produced) and textured steel surfaces. Surface texturing comprises hexagonal prism structures (with or without dimples) arranged in a honeycomb pattern with 50 µm or 100 µm gap spacing. Starting from the minimum printing size enabled by the 3D printing platform, various textures are prepared by scaling up the characteristic dimensions of the prisms up to 500%. The obtained surface patterns are characterized (qualitatively and quantitatively) using a non-contact computerized numerical control (CNC) measuring system. The coefficient of friction (COF) was investigated using a Ball-on-Disk configuration using bearing steel balls as counterparts. For a fixed sliding speed, different contact loads and sliding radii were considered, while the tests were carried out in either dry or lubricant-impregnated conditions. The results of wear tests in both dry and lubricated conditions indicated that the baseline samples are provided with lower COF compared to the textured ones. For the latter, neither the gap spacing nor the presence of dimples led to significant variations in the COF. However, in lubricated conditions, the values of the COF for baseline and textured surfaces were closer and much smaller. In particular, the results provide clear indications regarding reducing the gap between prisms, which had a beneficial effect on the COF in lubricated conditions. Similarly, sensitivity to dimples was quite remarkable, with a reduction in the COF of about 30% when the larger gap spacing between the prisms was used.

The use of ultra-short pulsed lasers enables the fabrication of laser-induced periodic surface structures (LIPSS) on various materials following a single-step, direct-writing technique. These specific, well-ordered nanostructures with periodicities in the order of the utilised laser wavelength facilitate the engineering of surfaces with functional properties. This review paper discusses the physical background of LIPSS formation on substrates with different material properties. Using the examples of structural colours, specific wetting states and the reduction of friction and wear, this work presents experimental approaches that allow to deliberately influence the LIPSS formation process and thus tailor the surface properties. Finally, the review concludes with some future developments and perspectives related to forthcoming applications of LIPSS-based surfaces are discussed. [ABSTRACT FROM AUTHOR]

Growing demand for superhydrophobic surfaces in recent years is associated to many attractive science and engineering applications including self-cleaning, anti-icing and anti-corrosive behaviours. Stainless steel type AISI 316L is one of the most versatile and widely used engineering material in industries. Inspired by the "lotus effect" nano/microstructures has been fabricated by direct laser writing method with nanosecond laser source using two ablation regimes. Primarily, microstructures were fabricated with a tightly focused beam and covered by nano-scale structures by defocused laser beam in the second fabrication step. However, freshly prepared laser patterned metal surface shows hydrophilic behaviour. The hydrophilic to superhydrophobic transformation takes several days or weeks by aging technique in atmospheric condition. In this study, the transition time has been drastically reduced by high vacuum processing technique. Wetting properties with respect to laser processing parameters and surface morphology were examined and found to be consistent for large droplet volumes. [ABSTRACT FROM AUTHOR]

Micro-structured surfaces are increasingly being used on parts and products to embed functional properties that could be optical, electrical, thermal, or likewise. In this work, directional optical properties were achieved on plastic with a microstructure composed of a close array of ridges, defined by a constant width and by the angle with respect to the normal of the generative surface. Under constrained lighting, the reflectance was maximized from a certain viewing angle and direction, and minimized from its horizontally orthogonal position. The purpose was the generation of quick response codes that could be easily scanned by means of commercially available software, e.g. smartphone applications, or professional equipment for identification or embedding specific information within the sample parts. To evaluate the functionality, defined as the generated light contrast from contingent micro ridges, the replicates were characterized by means of a robot assisted vision system, provided with a light source and a camera, used as a gonioreflectometer. The contrast was then correlated to the replication quality, i.e. the deviation of three defining parameters of the structures from the mould insert, thus determining the best processing conditions. The results showed that high injection speed, 60 °C mould temperature and 100 MPa packing pressure were required to achieve optimal replication and generated contrast: large variations in the surface functional behaviour were present even for small differences between the parts. However, an empirical approach highlighted that even for processing parameters that were less likely to promote replication, sufficient information decoding was achieved. [ABSTRACT FROM AUTHOR]

The article offers information on the Langmuir-Blodgett deposition techniques used to introduce molecular systems onto surfaces. Topics discussed include information on the utilising the Langmuir-Blodgett technique to transition from solution-based applications to functional surfaces; discussions on the Langmuir-Blodgett technique used to introduce metal-based functionality; and the Spin crossover complexes on Langmuir-Blodgett surfaces.

The distribution of surface functional groups was tuned through the use of the trimethylsilane spacer units which kept statistically fixed intermolecular intervals between functional molecules. We propose a simple and efficient procedure that does not require any optimization: statistical horizontal distances between the functionalities can be defined a priori regardless of the conditions of the functionalization (assuming only the minimal reaction time). We studied three various distributions of propyl silver carbonate functional units obtained through a five steps synthesis route. We showed that the quantity of immobilized complexes is proportional to the spacer density. The efficiency of the method was tested by differential pulse anodic stripping voltammetry (DPASV), which confirmed the assumed number of immobilized metal complexes on the sample surface. Unlabelled Image • The distribution of surface functional groups can be tuned using trimethylsilane spacer units. • Spacer units keep statistically fixed intermolecular intervals between the propyl silver carbonate molecules. • Three different distributions of functional units were studied. • The efficiency of the functionalization method was tested with DPASV technique. [ABSTRACT FROM AUTHOR]

Laser surface texturing is a promising technology for future wide applications of functional surfaces with specific properties like hydrophobic, antibacterial, adhesive, self-cleaning, anticorrosion, light absorbing, low friction, etc. Great advancements have been made in this field in the last few years, but in most cases, it takes from minutes up to 1 h to produce 1 cm2 of a functional surface. Even the availability of high-power ultrashort pulsed lasers in the last few years did not dramatically increase productivity, because there are physical limitations of current processing methods: heat accumulation and oxidation, plasma shielding effect, and precision at high speeds. In order to solve these limitations, there have been developed a new method called a shifted laser surface texturing (sLST) method. The new method has a potential to be at least 100 times more productive with no heat accumulation effect and virtually unlimited number of complex shape objects produced with high precision on the surface. In the present work, the principle and advantages of the method are described. The results of the method are compared with two standard methods (path filling of objects and hatch over all objects). The sLST method is presented in both single pulse and burst variants. Examples of its application on different materials for increased adhesion of surface coatings are shown. [ABSTRACT FROM AUTHOR]

We show that an azopolymer can be used to create a supramolecular architecture in a parallel process with patterned surface properties. By illuminating with an interference pattern, we created adhesion and charge patterns that reflect the molecular ordering. We studied the recording process in two limit situations. When birefringence dominates over mass transport, an adhesion pattern was recorded even in absence of a surface relief grating (SRG). When mass transport dominates, we measured a higher frequency adhesion and relief patterns on top of the SRG. We measured an increased negative charge in the regions where molecules are expected to be parallel aligned in trans conformational state. Image 1 • Supramolecular architectures with patterned surface properties are created in a parallel process. • Adhesion and electrical charge patterns are generated during the SRG recording process. • Azobenzene interactions enhance adhesion even in absence of SRG. • π - stacking interaction contributes to generate a charge pattern. [ABSTRACT FROM AUTHOR]