Influence Of Surface Patterning Research Articles

Research progress in construction and applications of surface patterned fibers

In nature, surface morphologies of organisms endow them versatile functions, e.g., drag reduction, strong adhesion, superhydrophobicity. Inspired by nature, researchers have made great progress in building micro/nano- patterns on planar substrate surfaces. However, the research on the patterning on fiber surface and its effect on the properties of fiber materials is still insufficient. In this paper, current construction methods of surface patterning on fiber surfaces were summarized, and fundamental mechanism of three “bottom-up” strategies was briefly described. Additionally, the influence of surface patterning on their properties was analyzed, and other potential applications of fiber materials in the future was prospected. Finally, the development trends of construction methods, formation mechanism and application were prospected. The purpose of this paper is to provide reference for both the construction of surface patterning on fibers and wide engineering applications of functional fiber/fabric.

The Influence of Surface Patterning on the Thermal Properties of Textured Thrust Bearings

Contact performance can be enhanced by using textured surfaces. These are also found to have influences on lubricated contacts. A procedure to find the optimal partially textured thrust bearing configuration is presented in this study. A parallel sector-pad thrust bearing is simulated by a three-dimensional (3D) computational fluid dynamics (CFD) model. The stationary surface of the bearing is textured with dimples, while the rotor surface is flat. The results of the baseline model are validated by experimental data. In this study, we compare rectangular and elliptical dimples by investigating design parameters, such as major the length of the major axis (width), the length of the minor axis (length), dimple depth, circumferential space between two dimples, radial space between two dimples, radial extent, circumferential extent are selected as design parameters. A parametric study is conducted to investigate the influence of the texture geometries and a surrogate model is created. Based on the surrogate model, a multi-objective optimization scheme is used to navigate the design space and find the optimal texture structure that provides a lower maximal temperature inside the fluid film, higher load capacity, and lower friction torque. The results show that the optimal radial extent of the texture is around 80% of the pad radial length for both cases. The optimal length of the elliptical dimples in the circumferential direction is about 30% larger than the value of the rectangular dimples. In the final optimal design, the maximal temperature reduces 1.1% and 1.3% for rectangular and elliptical dimples while the load capacities are maintained at the same level.

On the influence of surface patterning on tissue self-assembly and mechanics.

Extracellular matrix assembly and composition influence the biological and mechanical functions of tissues. Developing strategies to control the spatial arrangement of cells and matrix is of central importance for tissue engineering-related approaches relying on self-assembling and scaffoldless processes. Literature reports demonstrated that signals patterned on material surfaces are able to control cell positioning and matrix orientation. However, the mechanisms underlying the interactions between material signals and the structure of the de novo synthesized matrix are far from being thoroughly understood. In this work, we investigated the ordering effect provided by nanoscale topographic patterns on the assembly of tissue sheets grown in vitro. We stimulated MC3T3-E1 preosteoblasts to produce and assemble a collagen-rich matrix on substrates displaying patterns with long- or short-range order. Then, we investigated microstructural features and mechanical properties of the tissue in uniaxial tension. Our results demonstrate that patterned material surfaces are able to control the initial organization of cells in close contact to the surface; then cell-generated contractile forces profoundly remodel tissue structure towards mechanically stable spatial patterns. Such a remodelling effect acts both locally, as it affects cell and nuclear shape and globally, by affecting the gross mechanical response of the tissue. Such an aspect of dynamic interplay between cells and the surrounding matrix must be taken into account when designing material platform for the in vitro generation of tissue with specific microstructural assemblies.

Full Simulation Study of UV Photodetectors Based on Pn Junctions in Silicon Carbide

This paper deals with optical and electrical simulations of 4H-SiC UV-Photodetectors based on pn junctions. The simulations are performed under the UV light, with wavelengths varying between 200 nm and 300 nm. Under reverse bias, the simulation results point out the influence of surface patterns on the current density. The studied structures of the patterns consist in a semicircle with or without a flat surface. The patterned surfaces are parametrized according to the semicircle radius R and the flat surface length L. We show that the optical absorption strongly depends on these parameters, giving a maximum value whatever the wavelength with R = 100 nm and L = 0 nm (no flat surface). However, to optimise the carrier harvest, it is important for the space charge region to be situated in a zone where the optical generation is high. This study shows that the photodetector current density increases within three orders of magnitude (from 9x10-14 A.cm-2 to 3x10-10 A.cm-2), by using the specific surface pattern given above.

Influence of surface patterning on bacterial growth behavior

When cells colonize artificial materials, their growth behavior is undoubtedly influenced by physicochemical surface properties. In order to successfully untangle the numerous factors contributing to cell-surface interaction methods and tools are needed to reliably determine the significance of a single surface parameter without disturbing other influential factors. Especially studying the influence of purely physical properties, e.g., surface topography, in a microbiological in vitro assay is rather challenging. In an approach to provide microbiologists with a method suitable for this task, we demonstrate the fabrication of multiple, precisely defined microtopographies on a single elastomeric substrate that is designed to facilitate in vitro measurements. The applicability of these substrates is demonstrated by investigating the influence of microtopography on Staphylococcus aureus. Our findings suggest that microbial growth patterns are influenced by the underlying surface topography.

The influence of surface patterning and/or sterilization on the haemocompatibility of polycaprolactones

Platelet adhesion, coagulation and complement activation of flowing human blood over flat, nanostructured, sterilized or not sterilized surfaces of polycaprolactones (PCL) has been attempted. Two PCL samples were secured in place forming a parallel plate flow chamber. Platelet-poor plasma (PPP) or platelet-rich plasma (PRP) circulated for 30 min with a flow rate of 22 ml/min. The PPP was then collected to determine the nAPTT and the coagulation time as well as the amount of SC5b-9 and iC3b present. PRP was also collected under the same flow conditions and platelet counting was performed. Contact of blood with all PCL surfaces resulted in platelet adhesion with the phenomenon becoming more pronounced in the case of patterned surfaces. The coagulation time was affected by the nanopatterning. EB sterilization diminished platelet adhesion without significantly affecting the coagulation time. SC5b-9 complex activation increased with nanopatterning while iC3b activation was not affected by surface treatment.

Adhesion mechanisms of arc-sprayed zinc on concrete

Arc-sprayed zinc coatings can provide cathodic protection against corrosion to steel reinforcement in concrete. Because the adhesion of sprayed zinc on concrete is of major concern, the parameters related to zinc deposition and concrete preparation that affect the adhesion have been previously investigated. However, little attention has been devoted to determining which basic mechanisms are responsible for the adhesion of molten zinc on concrete. Because the interaction of molten zinc droplets with the concrete surface is considered physical, this paper is focused on the influence of surface patterns on the adhesion of arc-sprayed zinc coatings. Concrete surfaces were characterized by image analysis and profilometry techniques to ascertain which surface pattern or components could affect the adhesion of zinc. A modified root mean square (RMS) surface roughness was derived to take into account the different surface mor-phologies seen by sprayed zinc droplets. This modified RMS surface roughness was found to be directly related to the measured bond strength of arc-sprayed zinc on concrete. After the surface profile on con-crete is measured and the surface constituents are considered, the bond strength of arc-sprayed metals on concrete can be forecasted for given deposition parameters.