Surface Microtexture Research Articles

D145. A Novel “Smooth” Breast Implant Surface Design That Provides Implant Stability

PURPOSE: The risk of breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) has largely restricted surgeons to using smooth surfaced breast tissue expanders and implants, making the process of tissue expansion less predictable and obviating the application of anatomically shaped devices. Our group has developed a novel smooth breast implant surface that promotes tissue ingrowth into macropores (2-4mm in diameter within the implant surface) which facilitates tissue ingrowth into the shell of the implant and fixes the implant into position without the associated risks of microtextured devices. METHODS: Miniature anatomically (breast) shaped smooth implants (2cc) made from polydimethylsiloxane were designed with pores invaginating into the surface. A range of pore number (per implant), widths and depths were tested. Textured and smooth implant controls with no macropores were included. Implants were placed on the dorsum of wild-type rats (N=4 per group), implant rotation was evaluated monthly, and at explanation, implants were evaluated by gross visualization, histology, and Micro-CT. RESULTS: All macropore conditions demonstrated tissue ingrowth into pores by 1 month. Smooth implants experienced ~80 degrees more rotation than macropore implants at 3 months, and there was no significant difference between macropore and textured implant stability. Lower stability was noted when the macropore density and width decreased. CONCLUSION: We present an innovative design of “macropore” smooth implants which enhance implant positional stability without using the traditional microtextured surface linked to BIA-ALCL. These promising early results have led to ongoing follow-on studies to further identify the optimal macropore configuration that maximizes implant stability.

Predicting Sliding Angles on Random Pit-Distributed Textures Using Probabilistic Neural Networks

The three-phase contact line best reflects the sliding ability of droplets on solid surfaces. Most studies on the sliding angle (SA) of superhydrophobic surfaces are limited to regularly arranged microtextured surfaces, lacking definite models and effective methods for a complex surface of a random texture. In this study, random pits with an area ratio of 19% were generated on 1 mm × 1 mm subregions, and the subregions formed arrays on a sample surface of 10 mm × 10 mm to obtain a randomly distributed microtexture surface with no pit overlaps. Although the contact angle (CA) of randomly pitted texture was the same, the SA was different. The SA of surfaces was affected by the pit location. The location of random pits increased the complexity of the three-phase contact line movement. The continuity of the three-phase contact angle (T) can reveal the rolling mechanism of the random pit texture and predict the SA, but the relationship between the T and SA is a relatively poor linear relation (R2 = 74%), and the SA of the random pit texture can only be roughly estimated. The quantized pit coordinates and SA were used as the input and output labels for the PNN model, respectively, and the accuracy of the model convergence was 90.2%.

Early Cretaceous (late Barremian−Early Albian) expanding aeolian activity in East Asia: Evidence from the stratigraphic evolution of aeolian deposition in the Baiyin-Jingyuan Basin, northern China

Cretaceous aeolian deposition is important for understanding variations of the tropical−subtropical atmospheric circulation under the greenhouse background. Nevertheless, detailed records revealing the response of aeolian deposition to rising atmospheric CO2 are still lacking. To shed light on their linkage, we examined the Early Cretaceous stratigraphic evolution of the Hekou Group in the Baiyin-Jingyuan Basin, northern China, using multiple methods. The results indicate that the lower Hekou Group is characterized by a transition from submerged alluvial to shallow lacustrine deposition. Overlying these facies is loess-like deposition without bedding, distinguished by grain-size distribution, surface microtextures, and geochemical analysis, which is followed by palustrine deposition. In the palustrine deposition, aeolian sand-dune and sand-sheet deposition can be identified, which gradually developed upward in the Hekou Group, with intercalated wet interdunes, damp interdunes, and pebble-sand sheetflood beds. Finally, aeolian sand dunes and sand sheets dominated the upper Hekou Group. Overall, the upward-changing facies indicated the development of aeolian deposition from an aqueous environment, revealing a long-term paleoclimatic shift from semi-humid, semi-arid to extremely arid, which reflects the expanded aeolian activity in East Asia during the Early Cretaceous. Furthermore, various records were combined to investigate the expanding aeolian activity in East Asia, which indicates a west−east-trending arid belt that was wider than the modern counterpart during the late Barremian−Early Aptian and late Aptian−Early Albian, respectively. These stepwise expansions of aeolian activity were mainly driven by rising atmospheric CO2, which strengthened the subsiding branches of Hadley circulation and the subtropical high, eventually leading to intensified aridification.

Numerical Study on the Bearing Capacity of Lubricant Film in Journal Bearing with Micro-textured Surface

For studying the hydrodynamic lubrication performance of micro-textured radial journal bearings, a numerical model of hydrodynamic lubrication for journal bearings was established first. Solve the established numerical model using FDM, and the lubricant film pressure distribution and static characteristics of bearings were obtained. Considering the processing cost and feasibility of the processing technology, the cylindrical texture arranged in the radial of the bearing shell surface is applied, the lubricant film thickness equation considering the micro-texture is introduced into the Reynolds equation. According to the height and distribution density of microstructure, the bearing capacity parameters were obtained. The load-carrying capacity of micro structure journal bearing is significantly higher than that of plain bearing. In this paper, a practical model with cylindrical micro-textured surface is given for journal bearing applications with high capacity demand.

Conical Grinding Wheel Ultrasonic-Assisted Grinding Micro-Texture Surface Formation Mechanism

The rotating ultrasonic-assisted grinding (RUAG) experiment of the conical grinding wheel generated the intermittent pit-shaped micro-texture on the surface of the workpiece, reducing thermal damage and improving the lubrication characteristics compared with conventional grinding (CG). To further optimize the surface properties, this paper studied the formation mechanism of micro-texture. This study used as basis the theory that micro-debris volume equals the macroscopic material removal one to establish the mathematical equation of grinding depth. Thereafter, formulas of micro-texture feature parameters, including pit length, pit depth, and texture spacing were deduced. The solved microscopic grinding depth was alternatingly positive and negative, indicating that the alternating separation between the grinding grain and workpiece caused intermittent pits in the grinding. Through response surface analysis (RSA), this paper analyzed the relationships among macroscopic grinding depth, micro-texture feature parameters, and machining parameters (i.e., amplitude, feed rate, and rotational speed). Single-factor experiments of machining parameters, with finite element simulation and experiment methods, were performed to verify the theoretical micro-texture features. The simulated program formed three-dimensional surfaces with micro-textures. Their measurement results were consistent with the theoretical ones. Experimental results proved that the range of pit length covers the theoretical ones, further verifying the accuracy of the grinding depth model. For this grinding wheel, the 8–10 μm amplitude was optimal for better roughness, lubrication, and thermal damage. Roughness was improved when increasing the rotational speed or reducing the feed rate based on the experiment. If the rotational speed and feed rate exceed the limiting values, then continuous grinding will break down the abrasive grains and even damage the cubic boron nitride (CBN) coating. Experimental results likewise showed that the pit shape was closely related to the surface properties, which deserves further investigation.

Influence of alcoholic polar surfactants on PEDOT:PSS for enhanced performance of organic/Si hybrid solar cell

Conducting polymer, poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), has gained prominent interests in organic/n-Si hybrid solar cells (HSCs). Alcoholic polar solvents, 2-propanol (IPA) or methanol (MeOH) addition in PEDOT:PSS by simple solution mixing process have been investigated to arrest the critical issues related to poor affinity of aqueous (aq.) PEDOT:PSS on Si surface, a key prerequisite for efficient HSCs. Remarkably enhanced electrical conductivity of the polymer layer has been found for 100 v/v% IPA and 70 v/v% MeOH addition to the aq. PEDOT:PSS. Formation and performance of the PEDOT:PSS/n-Si junction under various concentration of the IPA and MeOH addition are investigated and compared with that of aq. PEDOT:PSS. The optimum IPA or MeOH addition led to structural modification of aq. PEDOT:PSS from coil-like benzoid to linear quinoid one and hence improved electrical properties. The polar solvents not only served as the surfactant leading to conductive PEDOT:PSS conformal coverage on the micro-textured Si surface but also offered modulation of optical, electrical, structural, morphological, and passivation properties of the polymer layer. Improved solar cell performance with maximum efficiency >11.50% could be achieved for optimum IPA added PEDOT:PSS/n-Si solar cells, which is ∼2.5 fold enhanced compared to that with aq. PEDOT:PSS. The study may lead to better understanding of PEDOT:PSS/n-Si interface and efficient hybrid photovoltaic devices employing the cost-effective polar surfactants.

Grain-size analysis and quartz surface microtextures observations of sediments from Jijelian East coast, Algeria: sedimentary environment implications

Grain-size analysis and quartz surface microtextures observations of sediments from Jijelian East coast, Algeria: sedimentary environment implications

Grain Shape Evolution of Sand‐Sized Sediments During Transport From Mountains to Dune Fields

AbstractGrain shape is used less frequently in identifying the origin of sediments than grain size distributions and/or surface microtextures because of technological limitations. In addition, systematic studies on grain shape change of sand‐sized sediments from a source‐to‐sink perspective are lacking, and yet the evolutionary mechanism of grain shape along the sediment transport pathway remains poorly understood. Here, we investigated grain shape changes in sand‐sized sediments ranging from mountains to dune fields using an efficient and quantitative dynamic image analysis technique. By means of the detailed hydro‐geomorphic analysis and field sampling in a quasi‐closed sedimentary system, we collected 41 samples from the Hulunbeier Sandy Land (HSL) in northern China and its potential source region. Also, 21 typical fluvial deposit samples from different river systems in China were collected for comparison. We identify that the sphericity, symmetry, aspect ratio, and mineralogical maturity of the fluvial deposits from mountains are significantly lower than the eolian sand in dune fields. Despite the apparent inheritance of sediments from the mountains to the dune fields, the abrupt changes in the sedimentological and geochemical properties along their pathway suggest that multiple cycles of eolian abrasion within the HSL modify the sediments significantly after they are transported away from the fluvial environments. The well‐defined separation between eolian sand and fluvial deposits by grain shape parameters such as sphericity and symmetry underscores that grain shape can be a powerful tool for tracing sediment transport history in paleoenvironmental or extraterrestrial studies.

Replication Study of Molded Micro-Textured Samples Made of Ultra-High Molecular Weight Polyethylene for Medical Applications

In articular joint implants, polymeric inserts are usually exploited for on-contact sliding surfaces to guarantee low friction and wear, a high load-bearing capacity, impact strength and stiffness, and biocompatibility. Surface micro-structuring can drastically reduce friction and wear by promoting hydrostatic friction due to synovial fluid. Ultra-High Molecular Weight Polyethylene (UHMWPE) is a suitable material for these applications due to its strong chemical resistance, excellent resistance to stress, cracking, abrasion, and wear, and self-lubricating property. However, surface micro-texturing of UHMWPE is hardly achievable with the currently available processes. The present study investigates UHMWPE's micro-textured surface replication capability via injection molding, comparing the results with the more easily processable High-Density Polyethylene (HDPE). Four different micro-texture cavities were designed and fabricated on a steel mold by micro-EDM milling, and used for the experimental campaign. Complete samples were fabricated with both materials. Then, the mold and samples were geometrically characterized, considering the dimensions of the features and the texture layout. The replication analysis showed that HDPE samples present geometrical errors that span from 1% to 9% resulting in an average error of 4.3%. In comparison, the UHMWPE samples display a higher variability, although still acceptable, with percentage errors ranging from 2% to 31% and an average error of 11.4%.

Effects of surface nanotexturing on the wickability of microtextured metal surfaces

Hypothesis: Achieving spontaneous, rapid, and long-distance liquid transport is crucial for many practical applications such as phase change heat transfer and reactions at solid–liquid interfaces. Surface nanotexturing has been widely reported to improve the wickability of microtextured metal surfaces. Although surface nanotextures show high capillary pressure, the high fluid flow resistance through nanotextures prevents fluid transport. The underlying mechanisms responsible for the enhanced wickability of nanotextured surfaces are still unclear.Experiments: Herein, we prepared a variety of microtextures and nanotextures on copper surfaces by femtosecond laser micromachining and chemical oxidation, respectively. The wickability of these textured surfaces was quantitively compared by measuring wicking coefficient and capillary rise speed. We designed experiments to eliminate any possible effects of surface oxidation and metal composition on wickability. A theoretical model describing the vertical and horizontal capillary flow in V-shaped microgrooves was proposed and utilized to analyze the experimental results. The effects of time-dependent wettability on wickability were also examined.Findings: Surface nanotexturing can enhance surface wettability while altering the micrometer-scale structural characteristics. The greatly enhanced wickability of nanotextured surfaces can only be observed when the surface microtextures have a very small aspect ratio. Otherwise, for metal surfaces with fine microgrooves, the latter effect is more pronounced, and thus the surface wickability may deteriorate after preparing surface nanotextures; for surfaces with wide microgrooves, both effects are minimal, and the surface wickability enhances only marginally after surface nanotexturing. Furthermore, the wickability of microtextured surfaces will decay rapidly due to the adsorption of airborne organics, whereas adding surface nanotextures can significantly inhibit this degradation. The anti-contamination capability of surface nanotextures is considered likely to be a potential mechanism responsible for the greatly enhanced wickability of nanotextured surfaces noted in some studies.

Experimental analysis of long-term skid resistance of steel slag asphalt mixture based on differential wear

ABSTRACT This study aimed to analyse the attenuation law of skid resistance of steel slag asphalt mixture (SSAM) based on differential wear. In this study, an indoor accelerated wear instrument was used to accelerate the wear of the SSAM surface. A pavement laser scanner and a dynamic friction tester measured the three-dimensional morphology and dynamic friction coefficient (μ) of SSAM. Then, the improvement mechanism of steel slag on the skid resistance of SSAM was expounded by analysing the surface microtexture, mineral composition, and chemical composition of aggregates. The results showed no linear relationship between the amount of steel slag and the improvement of SSAM skid resistance. The SSAM with 50% steel slag maximised the differential wear effect and had the largest μ and the richest surface macrotexture. It was recommended that the steel slag content in the SSAM should not exceed 50%. The more mineral composition and higher average hardness of steel slag were the sources of its excellent skid resistance. In addition, it is suggested that the differential wear between mixed aggregates should be considered in the design of skid resistance pavement, and the proportion of different aggregates should be reasonably distributed.

Superhydrophobic and oleophobic microtextured aluminum surface with long durability under corrosive environment

Superhydrophobic (SHP) and oleophobic aluminum surfaces have been prepared through the combination of a scalable chemical microtexturing process and surface functionalization with long-chained polyfluoroalkyl moieties. The effect of an anodic layer on the microtextured surface has been assessed considering surface morphology, superhydrophobicity, surface mechanical properties and corrosion protection enhancement. The surface functionalization with polyfluoroalkyl moieties has been tackled in two different ways: (i) grafting of the polyfluoroalkyl moieties and (ii) deposition of a thin hybrid coating with low content of polyfluoroalkyl-containing compound. Aluminum surfaces showing high durability in salt spray environments, which maintain SHP and oleophobic properties at least up to 2016 h have been attained. Applications for this kind of surfaces range from easy-to-clean surfaces to anti-icing or anti-condensation functionalities that could be of interest for several sectors.

Effect of Surface Micro-Texturing on the Tribological Properties of TiB-TiC/Co-Based Coatings by Laser Cladding

Effect of Surface Micro-Texturing on the Tribological Properties of TiB-TiC/Co-Based Coatings by Laser Cladding

Meshing frictional characteristics of spur gears under dry friction and heavy loads: Effects of the preset pitting-like micro-textures array

Despite good approval for excellent friction regulation, surface texturing seems to be a penalty area for gears mostly because of the traditional cognition of surface (micro-)pitting and structural similarity. Surface micro-textures were applied to the pinion flank to regulate the time-varying meshing stiffness and enhance the meshing characteristics. Results showed the stress regulation and smoothing capability of micro-textures in meshing process, the time-varying meshing stiffness increases by 4.75% and the frictional stability increased by 52%. Experiment results approve that the flank micro-textures can control friction and reduce torque by 26.2%. This study is significant for the systemic design of the dynamic performance and frictional meshing, especially for the gear engagement reliability in space without film lubrication.

Improvement of thermal plasma sprayed coating adhesion strength by laser microtexturing of aluminum

Grit blasting and laser processing are two common methods used for surface microtexturing to enhance coating adhesion strength. This paper reports a thermomechanical method of laser microtexturing of Al 7075 alloy using a nanosecond pulsed laser to generate a large increase in surface area. The entire surface area of the substrate was microtextured using laser melting, ablation, and resolidification. The laser microtextured surface morphology consisted of tightly packed pillar-like surface features. The morphology of the microtexture was varied by controlling the laser processing parameters. The laser microtextured surface was coated with metallic particles using a thermal spray process. The tensile adhesive strength of the thermally sprayed metallic coating was higher by over 17% for a 5-μm deep microtexture, compared to that of grit-blasted samples. Also, this is the highest reported adhesion strength for laser-based microtexturing methods for thermally sprayed bond coatings.

Biomimetic microtextured surfaces to improve tribological and antibacterial behaviors of 3Y-TZP ceramics

Surface texturing has been a powerful means to improve the service performance of various engineering materials. The 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) represents the most-used ceramic oxide in restorative dentistry due to its excellent esthetic effects, good chemical stability and superior biocompatibility. However, such materials show the limited ability of tribological and antibacterial performance for dental applications. In the present work, a bio-inspired design of textured surfaces was conducted based on the microstructural analysis of butterfly wings, peacock tail feathers, and dolphin skins to improve the service performances of 3Y-TZP ceramics for dental applications. Three types of microtextures, including micro-grids, micro-feathers, and micro-grooves, were fabricated onto the 3Y-TZP ceramics using the laser ablation technique. The effects of different microtextures on the wettability, tribological and antibacterial behaviors of 3Y-TZP ceramics were studied. The results indicate that all the biomimetic microtextures can effectively improve the service performance of 3Y-TZP. Wettability acts as a decisive factor for the tribological and antibacterial performances of textured ceramic surfaces. The bio-inspired microtextured surfaces all show hydrophobic behavior, thus yielding an effective improvement of antibacterial properties for 3Y-TZP. Moreover, the micro-grids inspired by the butterfly wings basically perform the best in tribological and antibacterial tests compared with the other counterparts.

Out-of-Plane Biphilic Surface Structuring for Enhanced Capillary-Driven Dropwise Condensation.

Rapid and sustained condensate droplet departure from a surface is key toward achieving high heat-transfer rates in condensation, a physical process critical to a broad range of industrial and societal applications. Despite the progress in enhancing condensation heat transfer through inducing its dropwise mode with hydrophobic materials, sophisticated surface engineering methods that can lead to further enhancement of heat transfer are still highly desirable. Here, by employing a three-dimensional, multiphase computational approach, we present an effective out-of-plane biphilic surface topography, which reveals an unexplored capillarity-driven departure mechanism of condensate droplets. This texture consists of biphilic diverging microcavities wherein a matrix of small hydrophilic spots is placed at their bottom, that is, among the pyramid-shaped, superhydrophobic microtextures forming the cavities. We show that an optimal combination of the hydrophilic spots and the angles of the pyramidal structures can achieve high deformational stretching of the droplets, eventually realizing an impressive "slingshot-like" droplet ejection process from the texture. Such a droplet departure mechanism has the potential to reduce the droplet ejection volume and thus enhance the overall condensation efficiency, compared to coalescence-initiated droplet jumping from other state-of-the-art surfaces. Simulations have shown that optimal pyramid-shaped biphilic microstructures can provoke droplet self-ejection at low volumes, up to 56% lower than superhydrophobic straight pillars, revealing a promising new surface microtexture design strategy toward enhancing the condensation heat-transfer efficiency and water harvesting capabilities.

Supreme-black levels enabled by touchproof microcavity surface texture on anti-backscatter matrix.

Emerging immersive high-dynamic range display technologies require not only high peak luminance but also true black levels with hemispherical reflectance below 0.001 (0.1%) to accommodate the wide dynamic range of the human eye (~105). Such low reflectance materials, denoted here as "supreme black," must exhibit near-perfect surface antireflection, extremely low in-matrix backscattering, and sufficient optical thickness, which, to date, have only been achieved by fragile sparse materials. We demonstrate a record-low hemispherical reflectance below 0.0002 (absorptance above 0.9998) in a touchproof material by satisfying the three requirements with a superwavelength surface microtexture with nanolevel details, low Mie backscattering composition, and optional additional underlayer. Our supreme black finishes are one to two orders of magnitude blacker than previously developed touchproof super-black materials. Thereby, unprecedented black levels enabling an ambient contrast ratio of ≳104 would be provided in display devices, contributing to immersive visual experiences that are critical for seamless remote collaboration and reliable virtual health care.

Morphology, microstructure, and electrocatalytical properties of sol-gel spin-coated Bi0.5Na0.5Ba(TiO3)2 thin films

Herein, we report, for the first time, the reduction reaction kinetics of ciprofloxacin organic molecules based on structural and micromorphological conditions of an electrocatalytic system of Bi0.5Na0.5Ba(TiO3)2 (BNT-BT) thin films. XRD analysis showed the coexistence of rhombohedral and tetragonal structures for the BNT-BT thin films annealed at 600, 650, and 700 °C, showing that the first one had a greater number of surface defects, which Raman spectroscopy confirmed. Analysis of the 3D micromorphological evaluation showed that an annealing temperature increase from 600 to 700 °C does not induce significant changes in the topographical profile. However, BNT-BT thin films annealed at 600 °C displayed more anisotropic surface microtexture, high spatial complexity, and low spatial frequencies. For the reactive surface of BNT-BT films, the electroanalytical assays showed that electrons from the conduction band are captured by oxygen adsorbed on the film surface, forming superoxide radicals that attack ciprofloxacin molecules, promoting their degradation. The best performance observed for the BNT-BT thin films annealed at 600 °C is attributed to their unique structural and micromorphological properties compared to the films annealed at higher temperatures. Our results prove that the proposed thin film deposition process is promising for developing new electrocatalytic devices.

Natural-convection heat transfer from regularly ribbed vertical surfaces: Homogenization-based simulations towards a correlation for the Nusselt number

Free-convection heat transfer from vertical surfaces is widely encountered in engineering applications, yet the role played by surface alterations in the heat transfer process and their practical effectiveness are still points of confusion. In this work, buoyancy-driven flows over periodically ribbed vertical plates of different surface micro-textures are investigated, mainly based on an asymptotic homogenization model through which the expensive resolution of the velocity and thermal fields within the inter-rib regions is bypassed, by imposing equivalent effective boundary conditions at a virtual plane surface. Efficiency of the homogenized simulations in detecting macroscopic behavior of the Nusselt number is first assessed, compared with full feature-resolving simulations in which the effects of complex flow patterns, near and within wall corrugations, on the local Nusselt number are captured. Second, the validated model is used to construct a database of numerical results describing deviations of the average Nusselt number over different ribbed surfaces, relative to a corresponding smooth surface. Under the conditions investigated, it is found that surface roughening generally deteriorates heat transfer from vertical surfaces, with slight enhancement for geometries characterized by low thermal slip, for example, rectangular ribs of narrow inter-rib spaces. Finally, a multiple-regression analysis is conducted to formulate a correlation describing effects of the thermal-slip coefficient, the number of ribs, and the Grashof number on the surface-averaged Nusselt number; accuracy of the proposed correlation is attested via further validation. This paper aims to call attention of the heat transfer society to the ability of the homogenization approach to considerably alleviate the computational requirements for relevant simulations and, thus, to significantly accelerate parametric optimization studies.