Surface Topography Of Substrate Research Articles

Phospholipid bilayer formation on a variety of nanoporous oxide and organic xerogel films

Lipid bilayers supported by nanoporous xerogel materials are being explored as models for cell membranes. In order to better understand and characterize the nature of the surface–bilayer interactions, several oxide and organic nanoporous xerogel films (alumina, titania, iron oxide, phloroglucinol–formaldehyde, resorcinol–formaldehyde and cellulose acetate) have been investigated as a scaffold for vesicle-fused 1,2-dioleoyl- glycero-3-phosphocholine (DOPC) lipid bilayer formation and mobility. The surface topography of the different substrates was analyzed using contact and tapping-mode atomic force microscopy and the surface energy of the substrates was determined using contact angle goniometry. Lipid bilayer formation has been observed with fluorescence microscopy and lateral lipid diffusion coefficients have been determined using fluorescence recovery after photobleaching. Titania xerogel films were found to be a robust and convenient support for formation of a two-phase DOPC/1,2-distearoyl- glycero-3-phosphocholine bilayer and domains were observed with this system. It was found that the cellulose acetate xerogel film support produced the slowest lipid lateral diffusion.

Evaluation of mechanical interlock effect on adhesion strength of polymer–metal interfaces using micro-patterned surface topography

This study concerns with the explanation of the wide range of adhesion strengths observed depending on the nature of substrate surface topography by linking macroscopic adhesion strength to microscopic energy-expenditure mechanisms during fracture. The dominant factors to which the adhesion strength of polymer–metal interfaces is attributed are investigated theoretically and experimentally. In an attempt to elucidate the effect of mechanical interlock on adhesion strength, micro-patterns were fabricated on metal surfaces as a designed surface topography. It was found that the molecular dissipation of the polymer in the vicinity of the interface is the major cause of the practical energy of separation. Furthermore, it is shown that loading mode controls the mechanical interlock effect, which is attributed to the fact that the stress distribution at the interface controls the deformation and failure characteristics of the polymer resin near the interface. Therefore, mechanical interlock promoted by adsorption provokes energy dissipation processes during fracture, which practically constitute the adhesion strength of a polymer–metal interface. The contribution of mechanical interlock to adhesion strength is systematically assessed by varying micro-pattern dimensions. The influence of the work of adhesion, cohesion and other dissipation energy on adhesion strength is examined by measuring each contribution to the total work of fracture.

Fractal dimension and surface topography on the diamond deposition of seeded WC–Co substrates

Diamond thin films were deposited on WC–Co substrates by hot filament chemical vapor deposition to improve the tribological performance. The influence of the substrate surface topography was found to play an important role during the nucleation stage and the later growth rate as well. In this study, we systematically investigated the relation between substrate surface irregularity, which was evaluated by fractal dimension as well as statistical roughness parameters and the quality of the later deposited diamond film. Preseeding processes, in diamond acetone suspensions with two particle diameters, by supersonic vibrator were also implemented to investigate the effect of particular size on diamond nucleation. The original surfaces were measured with a stylus profiler and contact-mode atomic force microscopy. The diamond deposited substrates were examined by scanning electron microscopy, x-ray diffractometry, Raman spectroscopy, and Rockwell-C indentation to study substrate topography, crystalline structure of the coating, the composition of diamond films, and adhesion between deposited layers and substrates, respectively. The synergetic influence of the substrate’s fractal dimension and the particular size of pre-seeding diamond suspension were studied and addressed. The deposited film of a WC–Co substrate with higher surface fractal dimension (>2.50), preseeded by fine diamond suspension (4–12 nm particle size) in advance, has a high diamond-rich composition and adhesion strength.

Effect of substrate surface topography on forensic development of latent fingerprints with iron oxide powder suspension

AbstractLatent fingerprint deposition and effectiveness of detection are strongly affected by the surface on which prints are deposited. Material properties, surface roughness, morphology, chemistry and hydrophobicity can affect the usefulness or efficacy of forensic print development techniques. Established protocols outline appropriate techniques and sequences of processes for broad categories of operational surfaces. This study uses atomic force microscopy and scanning electron microscopy to investigate a series of surfaces classified as smooth, non‐porous plastic. Latent prints developed with iron oxide powder suspension are analysed on a range of scales from macro to nano to help elucidate the interaction mechanisms between the latent fingerprint, development agent and underlying surface. Differences between surfaces have a strong effect, even within this single category. We show that both average roughness and topographical feature shape, characterised by skew, kurtosis and lay, are important factors to consider for the processing of latent fingerprints. Copyright © 2010 John Wiley & Sons, Ltd.

In vitro reaction of human osteoblasts on alumina‐toughened zirconia

Alumina toughening enhances the mechanical properties of zirconia ceramics but the biocompatibility of this material has rarely been addressed. In this study, we examined the osteoblast response to alumina-toughened zirconia (ATZ) with different surface topographies. Human osteoblasts isolated from maxillary biopsies of four patients were cultured and seeded onto disks of the following substrates: ATZ with a machined surface, airborne-particle abraded ATZ, airborne-particle abraded and acid etched ATZ. Airborne-particle abraded and acid etched titanium (SLA) and polystyrene disks served as a reference control. The surface topography of the various substrates was characterized by profilometry (R(a), R(p-v)) and scanning electron microscopy (SEM). Cell proliferation, cell-covered surface area, alkaline phophatase (ALP) and osteocalcin production were determined. The cell morphology was analyzed on SEM images. The surface roughness of ATZ was increased by airborne-particle abrasion, but with the R(a) and R(p-v) values showing significantly lower values compared with SLA titanium (Mann-Whitney U-test P<0.05). The proliferation assay revealed no statistically significant differences between the ATZ substrates, SLA titanium and polystyrene (Kruskal-Wallis test, P>0.05). All substrates were densely covered by osteoblasts. ALP and osteocalcin production was similar on the examined surfaces. Cell morphology analysis revealed flat-spread osteoblasts with cellular extensions on all substrates. These results indicate that ATZ may be a viable substrate for the growth and differentiation of human osteoblasts. Surface modification of ATZ by airborne-particle abrasion alone or in combination with acid etching seems not to interfere with the growth and differentiation of the osteoblasts.

Research Highlights

Research Highlights

Filling of very deep, wide trenches by BenzoCycloButene polymer

A process for deep trench filling by BenzoCycloButene (BCB) polymer is explored. Deep trenches with 100-μm depth and different aspect ratios from 1.4 to 20 have been successfully filled by BCB. Besides, chemical mechanical polishing (CMP) of BCB is studied with the main goals of smoothing surface topography of substrate after BCB filling and removing excess BCB coating which may be necessary in some applications. Removal rate for BCB, V RR, of about 0.24 μm/min has been achieved for hard cured BCB films using acid slurry. After CMP, the BCB layer showed a roughness of about 1.36 nm (Rq, measured by atomic force microscopy, AFM).

Inkjet printing and adhesion characterisation of conductive tracks on a commercial printed circuit board material

Silver nanoparticle-based conductive tracks were inkjet printed using a piezoelectric drop-on-demand inkjet printer on a commercially available electronics grade fibre glass (E-glass) reinforced substrate material, and the experimental results have been summarised. Ink jetting was done on two variants of this substrate material, viz. etched and unetched, to determine the influence of substrate surface topography on adhesion and accuracy of the printed tracks. The pull-off adhesion test method was used to quantify adhesive strength. The dependence of the pull-off test results on local geometry of the test area are illustrated with the aid of scanning electron microscope images and interferometer studies. Based on the outcomes of the experiments, conclusions concerning the suitable surface topography for inkjet printing have been arrived at.

“Lock‐and‐Key” Geometry Effect of Patterned Surfaces: Wettability and Switching of Adhesive Force

A rough surface can be a regular (engineered surface), a random (irregular rough surface), or an intermediate case (hierarchical rough surface). Whichever case is used for wettability, a truly superhydrophobic surface exhibits not only a high contact angle (>150 8) but also a low-contact-angle hysteresis (sliding angle). Quere et al. theoretically described how contact-angle hysteresis generates an adhesive force and the contact angle and hysteresis can be controlled by tailoring the surface topography of the solid substrate. Researchers have since attempted to capture these properties in synthetic materials with nanoscale surface features or changes of surface topography. For flexibility in adapting to rough surfaces, poly (dimethylsiloxane) (PDMS) elastomer, an ideal elastic material in terms of its stress–strain response, has attracted great attention. Particular interest has focused on introducing nanoscale structures onto microscale surfaces using surface treatments to reach a hydrophobic state, such as mechanically assembled monolayers, CO2 pulsed-laser etching, [8–10] UV/ ozone surface treatments, SF6 plasmas, [12] oxygen plasma and chemical surface treatments, and laser etching. Besides these, Hang et al. created an artificial lotus leaf by

Influence of substrate surface topography in the deposition of nanostructured diamond-like carbon films by high density plasma chemical vapor deposition

In this work, we have studied the influence of the substrate surface condition on the roughness and the structure of the nanostructured DLC films deposited by High Density Plasma Chemical Vapor Deposition. Four methods were used to modify the silicon wafers surface before starting the deposition processes of the nanostructured DLC films: micro-diamond powder dispersion, micro-graphite powder dispersion, and roughness generation by wet chemical etching and roughness generation by plasma etching. The reference wafer was only submitted to a chemical cleaning. It was possible to see that the final roughness and the sp 3 hybridization degree strongly depend on the substrate surface conditions. The surface roughness was observed by AFM and SEM and the hybridization degree of the DLC films was analyzed by Raman Spectroscopy. In these samples, the final roughness and the sp 3 hybridization quantity depend strongly on the substrate surface condition. Thus, the effects of the substrate surface on the DLC film structure were confirmed. These phenomena can be explained by the fact that the locally higher surface energy and the sharp edges may induce local defects promoting the nanostructured characteristics in the DLC films.

Scanning Probe‐based Fabrication of 3D Nanostructures via Affinity Templates, Functional RNA, and Meniscus‐mediated Surface Remodeling

Developing generic platforms to organize discrete molecular elements and nanostructures into deterministic patterns on surfaces is one of the central challenges in the field of nanotechnology. Here we review three applications of the atomic force microscope (AFM) that address this challenge. In the first, we use two-step nanografting to create patterns of self-assembled monolayers (SAMs) to drive the organization of virus particles that have been either genetically or chemically modified to bind to the SAMs. Virus-SAM chemistries are described that provide irreversible and reversible binding, respectively. In the second, we use similar SAM patterns as affinity templates that have been designed to covalently bind oligonucleotides engineered to bind to the SAMs and selected for their ability to mediate the subsequent growth of metallic nanocrystals. In the final application, the liquid meniscus that condenses at the AFM tip-substrate contact is used as a physical tool to both modulate the surface topography of a water soluble substrate and guide the hierarchical assembly of Au nanoparticles into nanowires. All three approaches can be generalized to meet the requirements of a wide variety of materials systems and thereby provide a potential route toward development of a generic platform for molecular and materials organization.

Influence of crystal orientation and surface topography of aluminum substrate on pore nucleation of anodic porous alumina

Pore nucleation and growth processes of anodic oxide films formed on aluminum substrate were investigated by atomic force microscopy with focusing on the crystal orientation and surface topography of aluminum substrate. Nanotopographies of electropolished aluminum were extremely affected by the crystal orientation of aluminum substrate. For as-received aluminum, regularly aligned striped structure appeared after electropolishing. On the other hand, aluminum substrate annealed at 300°C exhibited isotropic hexagonal cell structure. From X-ray diffraction patterns, it was confirmed that the preferential crystal orientation of aluminum was changed from (110) to (100) when annealing temperature was higher than 300°C. In the initial stage of anodization, specific nanotopography of electropolished aluminum surface was served as the initiation sites for pore generation, and accordingly it influenced cell arrangement. Using planarized aluminum with less than 0.3 nm asperities, however, a large number of fine pores initiated on the oxide film surface. Thus, the growth of anodic oxide films was seriously influenced by the surface topography of aluminum substrate.

PLD bioactive ceramic films: the influence of CaO–P2O5 glass additions to hydroxyapatite on the proliferation and morphology of osteblastic like-cells

This work consists on the evaluation of the in vitro performance of Ti6Al4V samples PLD (pulsed laser deposition) coated with hydroxyapatite, both pure and mixed with a CaO-P2O5 glass. Previous studies on immersion of PLD coatings in SBF, showed that the immersion apatite films did not present the usual cauliflower morphology but replicated the original columnar structure and exhibited good bioactivity. However, the influence of glass associated to hydroxyapatite concerning adhesion, proliferation and morphology of MG63 cells on the films surface was unclear. In this study, the performance of these PLD coated samples was evaluated, not only following the physical-chemical transformations resulting from the SBF immersion, but also evaluating the cytocompatibility in contact with osteoblast-like MG63 cells. SEM and AFM confirmed that the bioactive ceramic PLD films reproduce the substrate's surface topography and that the films presented good adherence and uniform surface roughness. Physical-chemical phenomena occurring during immersion in SBF did not modify the original columnar structure. In contact with MG63 cells, coated samples exhibited very good acceptance and cytocompatibility when compared to control. The glass mixed with hydroxyapatite induced higher cellular proliferation. Cells grown on these samples presented many filipodia and granular structures, typical features of osteoblasts.

Effect of Droplet Characteristics and Substrate Surface Topography on the Final Morphology of Plasma-Sprayed Zirconia Single Splats

The morphology of atmospheric plasma-sprayed yttria-stabilized zirconia single splats has been studied. Single splats of plasma-sprayed ZrO2-7%Y2O3 powder have been collected on polished stainless steel substrates kept at three different temperatures (room temperature, 300 °C, and 600 °C). The effect of heating on the substrates’ surface topography was evaluated. The effects of spray process parameters such as substrate temperature, particle temperature, and velocity on the morphology of single splats was studied. Variation of splat shape with location within the footprint of plasma spray was investigated. Pore and microcrack formation, splashing behavior, splat/substrate, and splat/splat interfaces were analyzed. Splat morphology and diameter, satellite particles, and splashing behavior were recorded using both scanning electron microscopy and image analysis. Splat/substrate and splat/splat interfaces were studied from cross sections prepared by focused ion beam milling. Results showed primarily disk-shape morphology and no evidence of delamination along the splat/substrate interface at 600 °C substrate temperature. Overlapped splats showed evidence of melting (microwelding) at splat boundaries. Splat thickness was measured to be less than 1 μm for all spray conditions.

Grit blasting of Ti–6Al–4V alloy: Optimization and its effect on adhesion strength of plasma-sprayed hydroxyapatite coatings

The effect of grit blasting parameters on the surface roughness of Ti–6Al–4V alloy as the substrate for plasma-sprayed hydroxyapatite (HA) coatings was examined using the factorial and Taguchi designs of experiments. In this study, two grit materials (Al2O3 and SiO2) each at two sizes, and two types of blasting systems (pressure and suction) were used. An equivalent surface roughness of 3.51 μm was obtained in three optimum conditions. The results of the Taguchi designed experiments were analyzed using signal to noise ratio. The tensile bonding strength of HA coatings deposited on the roughened substrates at the three different optimum conditions was measured by the standard adhesion test (ISO 13779-4). As the crystallinity of the coating at the interface, evaluated by the XRD analysis, reduced the bonding strength of the coatings was increased. These findings suggest that the substrate surface topography significantly influences the properties of the coating at the interface.

Laser surface treatment of hydroxyapatite for enhanced tissue integration: Surface characterization and osteoblastic interaction studies

Biocompatibility has long been associated with surface microtopography, microtexture, and microchemistry. The surface topography eventually affects the nature and the intensity of the interactions that occur at biomaterial-biological interface (cell adhesion, mobility, spreading, and proliferation). Therefore, it is necessary to produce and work with controlled microtopographical surfaces that present reproducible microdomains of a dimension similar to that of the biological elements of interest (in this case, osteoblasts). There are a number of substrates that already have been studied in terms of surface topography; however, few studies are related to hydroxyapatite (HA) substrates. As it is well established, HA is a well-known ceramic that is extremely used in medical applications, namely implants and coatings. In this work, the surface topography of dense HA substrates was altered by using KFr excimer laser. The surface was characterized by atomic force microscopy and contact angle measurements, while the cell distribution and morphology was assessed by scanning electron microscopy and confocal laser scanning microscopy. Results revealed that the surface is characterized by a homogeneous columnar structure with high specific area. Moreover, cells were able to attach and spread on the surface of the samples, and gradually grow into nearly confluent monolayers.

Carbon Nanotube Growth on Different Types of Tool Steel Substrates

ABSTRACTThis paper investigates the effectiveness of different pretreatment methods applied on M50, M35, and W4 type of tool steel substrates for direct growth of carbon nanotubes. The pretreatments explored include treatment with sand paper polishing, nitric acid (HNO3) etching, and high temperature hydrogen gas treatment. Furthermore, in order to establish a correlation between the steel surface average roughness value and the carbon nanotube growth, surface topography of steel substrates created by mechanical polishing were measured before actual growth process. Grown carbon nanostructures were shown by SEM and TEM to be multi-walled carbon nanotubes (MWCNTs) and vapor grown carbon nanofibers (VGCFs). It was found that under the same pretreatment conditions, even when the same roughness values were achieved and the same thermal chemical vapor deposition conditions were applied, grown nanostructures on different types of tool steel substrates showed dissimilarity.

Requirement for both micron- and submicron scale structure for synergistic responses of osteoblasts to substrate surface energy and topography

Objective Surface roughness and surface free energy are two important factors that regulate cell responses to biomaterials. Previous studies established that titanium (Ti) substrates with micron-scale and submicron scale topographies promote osteoblast differentiation and osteogenic local factor production and that there is a synergistic response to micro-rough Ti surfaces that have retained their high surface energy via processing that limits hydrocarbon contamination. This study tested the hypothesis that the synergistic response of osteoblasts to these modified surfaces depends on both surface micro-structure and surface energy. Methods Ti disks were manufactured to present three different surface structures: smooth pretreatment (PT) surfaces with R a of 0.2 μm; acid-etched surfaces (A) with a submicron roughness R a of 0.83 μm; and sandblasted/acid-etched surfaces (SLA) with R a of 3–4 μm. Modified acid-etched (modA) and modified sandblasted/acid-etched (modSLA) Ti substrates, which have low contamination and present a hydroxylated/hydrated surface layer to retain high surface energy, were compared with regular low surface energy A and SLA surfaces. Human osteoblast-like MG63 cells were cultured on these substrates and their responses, including cell shape, growth, differentiation (alkaline phosphatase, osteocalcin), and local factor production (TGF- β1, PGE 2, osteoprotegerin (OPG)) were analyzed ( N=6 per variable). Data were normalized to cell number. Results There were no significant differences between smooth PT and A surfaces except for a small increase in OPG. Compared to A surfaces, MG63 cells produced 30% more osteocalcin on modA, and 70% more on SLA. However, growth on modSLA increased osteocalcin by more than 250%, which exceeded the sum of independent effects of surface energy and topography. Similar effects were noted when levels of latent TGF- β1, PGE 2 and OPG were measured in the conditioned media. Conclusions The results demonstrate a synergistic effect between high surface energy and topography of Ti substrates and show that both micron-scale and submicron scale structural features are necessary.

Influence of Surface Character Change of Substrate Due to Heating on Flattening Behavior of Thermal Sprayed Particles

The authors have confirmed that in the thermal spraying of practical powder materials, the splat shape changes with increasing substrate temperature to a circular disk shape from a fringe shape with splashing at a critical substrate temperature, T t . The increase of the substrate temperature may accompany a kind of essential change on the substrate surface, because the effect is maintained until the substrate is cooled down to room temperature. However, the nature of the substrate surface change due to the heating has not been clearly understood yet. In this study, AISI 304 stainless steel was used as a substrate material, and the substrate was heated in an air atmosphere or laser treated as a pretreatment. Substrate surface topography in nanometer scale was analyzed precisely by atomic force microscope (AFM). The relationship between surface topography in nanometer scale and splat morphology was discussed. Moreover, to evaluate the effect of chemical composition of the substrate surface, gold was coated onto the substrate surface by physical vapor deposition (PVD) after the heat treatment. The effect ofadsorbate/condensate on the substrate surface on the flattening behavior of thermal sprayed particles was also verified.

Osteoblast Proliferation and Morphology Analysis on Laser Modified Hydroxyapatite Surfaces: Preliminary Results

Biocompatibility has long been associated with surface microtopography, microtexture and microchemistry. The surface topography ultimately affects the nature and the strength of the interactions that occur at biomaterial-biological environment (cell adhesion, mobility, spreading and proliferation). Thus, it is necessary to produce and work with controlled microtopographical surfaces that present reproducible microdomains of a dimension similar to that of the biological elements of interest (for instance, cells). [1] There are a number of substrates that already have been studied (such as silicone, polystyrene, poly-L-lactic acid and titanium coated polystyrene) in terms of surface topography. [2] However, few studies are related to hydroxyapatite substrates. As it is well established, hydroxyapatite is a well known ceramic that is extremely used in medical applications, namely implants and coatings. In this work, the surface topography of dense hydroxyapatite substrates was altered by using KFr excimer laser. Excimer lasers produce high-intensity, pulsed ultraviolet radiation and are especially well suited for materials processing due to their large beam cross-section area, which permits using mask projection technologies to process relatively large areas in a single step.[3]