Micron-scale Roughness Research Articles

Infrared spectroscopy of volcanoes: from laboratory to orbital scale

Understanding the composition, texture, and morphology of volcanic rocks that have erupted at the surface better constrains the eruption style and is vital to infer subsurface processes, the development of magma upon ascent, and the potential for future eruptions. The reflectance and emission spectroscopy of these rocks, collected from the near-infrared (NIR) through the thermal infrared (TIR) portion of the electromagnetic (EM) spectrum, provides the data necessary to retrieve composition, micron-scale surface roughness, and particle size. Remote imaging systems enable the analyses of active volcanoes in remote regions, where sample collection for laboratory analysis poses a significant challenge. Laboratory hyperspectral data of samples acquired at volcanic deposits are easily resampled to the spectral resolution of any infrared sensor and provide a means of estimating the composition of volcanoes and their products worldwide, as well as those on other planetary bodies such as the Moon and Mars. In this review paper, we provide an overview of the current use of infrared reflectance and emission spectroscopy as an analysis tool in volcanology, including ground-based imaging systems that acquire unprecedented detail and serve as testbeds for new orbital concepts. We also discuss the potential impact that future satellite missions will have on volcano science as spectral, spatial, and temporal resolutions improve.

The roles of sub-micron and microscale roughness on shear-driven thrombosis on titanium alloy surfaces.

Continuous-flow ventricular assist devices (cfVADs) are implanted in patients with end-stage heart failure to assist with blood circulation. However, VAD implantation is associated with dangerous thrombotic complications. Our goal was to determine the impact of micron and sub-micron scale Ti6Al4V surface roughness on adherent platelet aggregate properties under clinically relevant shear rates. We used fluorescence microscopy to visualize platelets in real time as they adhered to Ti6Al4V coupons of varying degrees of roughness, including a smooth control, in microfluidic channels and quantified deposition using an image processing algorithm. We systematically characterized roughness using spatial frequencies to generalize results for more blood-biomaterial contact applications. We observed that on the control and sub-micron rough surfaces, at 1000 s-1 , platelets adhered uniformly on the surface. At 2000 s-1 , we observed small and stably adherent platelet aggregates. At 5500 s-1 , platelet aggregates were large, unstable and interconnected via fibrillar structures. On a surface with micron-scale roughness features, at all three shear rates, platelets deposited in the troughs of the roughened surface, and formed aggregates. Thrombus height at 2000 s-1 and 5500 s-1 was greatest on the roughest surface and lowest on the mirror-finished surface, as indicated by the mean fluorescence intensity. These results demonstrated that at high shear rates, thrombi form regardless of surface topography at the scales applied. At lower shear rates, micron-scale surface features cause thrombus formation, whereas submicron features result in innocuous platelet adhesion. These findings have implications for manufacturing costs and other considerations.

Composite GO/Ceramic Membranes Prepared via Chemical Attachment: Characterisation and Gas Permeance Properties.

Graphene oxide (GO) oligo-layered laminates were self-assembled on porous ceramic substrates via their simple dip-coating into aqueous GO dispersions. To augment the stability of the developed composite GO/ceramic membranes and control the morphology and stacking quality of the formed laminate, short-((3-glycidoxypropyl)trimethoxy silane-GLYMO, (3-aminopropyl)triethoxy silane-APTES), and long-chain (polydopamine-PDA) molecules were involved and examined as interfacial linkers. A comparative study was performed regarding the linker's capacity to enhance the interfacial adhesion between the ceramic surface and the GO deposit and affect the orientation and assemblage characteristics of the adjacent GO nanosheets that composed the formed oligo-layered laminates. Subsequently, by post-filtrating a GO/H2O suspension through the oligo-layered laminate membranes, the respective multi-layered ones have been developed, whereas ethylenediamine (EDA) was used in the suspension as an efficient molecular linker that strongly bonds and interlocks the GO nanosheets. The definition of the best linker and approach was conducted on macroporous α-alumina disks, due to the use of inexpensive raw materials and the ability to fabricate them in the lab with high reproducibility. To validate the concept at a larger scale, while investigating the effect of the porous substrate as regards its micrometer-scale roughness and surface chemistry, specific chemical modifications that yielded membranes with the best gas permeability/selectivity performance were replicated on a commercial single-channel monolith with a ZrO2 microfiltration layer. XRD, Raman, ATR, FESEM, and XPS analyses were conducted to study the structural, physicochemical, surface, and morphological properties of the GO/ceramic composite membranes, whereas permeance results of several gases at various temperatures and trans-membrane pressures were interpreted to shed light on the pore structural features. Concerning the short-chain linkers, the obtained results ascertain that GLYMO causes denser and more uniform assembly of GO nanosheets within the oligo-layered laminate. PDA had the same beneficial effect, as it is a macromolecule. Overall, this study shows that the development of gas-separating membranes, by just dipping the linker-modified substrate into the GO suspension, is not straightforward. The application of post-filtration contributed significantly to this target and the quality of the superficially deposited, thick GO laminate depended on this of the chemically attached oligo-layered one.

A study of interfacial electrical contact resistances of thermoelectric generators for hypersonic vehicles by experimental measurements and two-scale numerical simulations

An enormous amount of aerodynamic heat is produced on the surface of hypersonic vehicles, and the thermoelectric generator (TEG) technique holds the potential to convert aerodynamic heat into electric energy. In a TEG, the micrometer-scale roughness on TE legs and electrodes surfaces leads to the constriction of interfacial electric current and brings about electrical contact resistance (ECR). The heat transfer and conversion processes of a TEG are greatly influenced by such type of ECR. In this work, a TEG includes two ceramic substrates and a middle TE layer is established, and the TE layer consists of insulation material, N- and P-type TE legs and electrodes to connect the TE legs. The ECR and its effects on the TEG performance are studied by two-scale numerical simulations and experimental measurements. First, the practical topography of rough surfaces for TE legs and electrodes is measured, and the micrometer-scale ECR prediction numerical models are established based on the reconstructed topography. An ECR measurement platform is developed and the platform consists of a pressure device, power supply and data acquisition system which are used to provide loading pressures, voltage, and acquisition of electric current and voltage signals, respectively. The ECRs under different temperatures, loading pressures and gap mediums are then predicted and the numerical models are validated by a series of measurements. Second, the TE conversion process of TEG is simulated by a millimeter-scale model including insulation materials, TE legs, electrodes, and equivalent interfacial layers of ECR. The influence of ECR on the TE performance of TEG for the hypersonic vehicle is thus clarified.

Enhanced photocontrollable dynamic adhesion of nematic elastomers on rough surfaces

Polymers with switchable adhesion properties are important for efficient catch-and-release processes in robotic hand applications and handgrips with on-demand adhesion control. However, counter objects often have a rough surface topography, which requires a dynamic adhesion system that balances adhesion and detachment performances. Here, we demonstrate that a photosensitive nematic main-chain liquid crystal elastomer (LCE) has suitable photoswitchable adhesion properties on surfaces with micrometer-scale roughness, resulting in a large adhesion change. The nematic LCE exhibits the so-called “soft elasticity,” wherein it can deform at a certain strain without increasing the elastic energy. Such deformation can be maintained owing to arrested relaxation, enabling the LCE to deform along with a rough surface upon light pressure. This increases the contact area and consequently enhances adhesion ability. On the other hand, the LCE exhibits rubber elasticity after proper light irradiation owing to a phase transition from the nematic to the isotropic phase. As rubber elasticity limits deformation, the contact area on the rough surface, and thus the adhesion, is greatly reduced. This LCE with photoswitchable elasticity has great merit as a dynamic adhesive pad for treating objects with rough surfaces, which may expand the versatility of stimuli-responsive adhesive systems.

Vibration sorting of small droplets on hydrophilic surface by asymmetric contact-line friction.

Droplet spreading and transport phenomenon is ubiquitous and has been studied by engineered surfaces with a variety of topographic features. To obtain a directional bias in dynamic wetting, hydrophobic surfaces with a geometrical asymmetry are generally used, attributing the directionality to one-sided pinning. Although the pinning may be useful for directional wetting, it usually limits the droplet mobility, especially for small volumes and over wettable surfaces. Here, we demonstrate a pinning-less approach to rapidly transport millimeter sized droplets on a partially wetting surface. Placing droplets on an asymmetrically structured surfaces with micron-scale roughness and applying symmetric horizontal vibration, they travel rapidly in one direction without pinning. The key, here, is to generate capillary-driven rapid contact-line motion within the time-scale of period of vibration. At the right regime where a friction factor local at the contact line dominates the rapid capillary motion, the asymmetric surface geometry can induce smooth and continuous contact-line movement back and forth at different speed, realizing directional motion of droplets even with small volumes over the wettable surface. We found that the translational speed is selective and strongly dependent on the droplet volume, oscillation frequency, and surface pattern properties, and thus droplets with a specific volume can be efficiently sorted out.

Water drop impacts on regular micropillar arrays: The impact region

A liquid drop impact on to a rough solid typically produces an “impact region,” which is an area of fully wetted surface smaller than or equal to the projected area of the drop. Here, high-speed photography is used to study the size and symmetry of this impact region and microbubbles within it for water drop impacts on regular square arrays of hydrophobic micropillars. Outcomes are most strongly influenced by pillar pitch and impact Weber number (We), and there is an apparent transition from vertical to more horizontal wetting near the edge of the projected area of the falling drop. The impact region size is well described by energetic and pinning transition analyses, but profound asymmetries are observed, indicating the influence and superposition of cross-flows for gas and liquid escape. Zipping of the liquid–air interface between pillars during later stages of drop spreading is also studied. The surfaces have 20 μm wide polydimethylsiloxane pillars of circular or square cross section. Variations in array pitch (40–80 μm) and height (15–30 μm) are systematically investigated using droplets of diameter 2.51 ± 0.04 mm over the range 50< We < 250. The geometric regularity of these surfaces could give rise to technological applications, but the results are also relevant to the many natural and industrial processes in which liquid drops impact upon dry surfaces with micrometer scale roughness.

Matrix wettability and mechanical properties of geopolymer cement-polydimethylsiloxane (PDMS) hybrids

Geopolymers have attracted attention as green building materials with low carbon dioxide emissions and excellent mechanical properties. Due to their hydrophilicity and porous structure, geopolymers can be infiltrated by water involving harmful ions. In this study, the effects of polydimethylsiloxane (PDMS) as an additive on the wettability, mechanical properties and microstructure of metakaolin-based geopolymer were investigated. The microstructure was characterized by MIP, μ-XCT, SEM, EDX, TIM, XRD, FTIR and 29Si NMR test. As the PDMS content increased, the geopolymer became hydrophobic, increasing its contact angle to approximately 140°. This hydrophobicity mainly results from the chemical modification and the increased roughness of the matrix. PDMS, with the content over 1.5 mL/L, can raise the porosity and pore size of the geopolymer, and promote the transformation of small gel pores into transitional and capillary pores. The fluffy pore structures and cured hybrids jointly created nano-scale and micron-scale roughness structures. No new crystalline phases will be generated by adding PDMS. The compressive strength increased with the addition of a small amount of PDMS, while it began to decrease when the PDMS content exceeded 10 mL/L. The effect of PDMS with different contents on the pore and silicate structure of geopolymers leads to changes of mechanical properties. The hybridization mechanism of PDMS molecules and N-A-S-H was summarized based on microstructure analysis.

Fluorine-Free Superhydrophobic Coating with Antibiofilm Properties Based on Pickering Emulsion Templating.

This study presents antibiofilm coating formulations based on Pickering emulsion templating. The coating contains no bioactive material because its antibiofilm properties stem from passive mechanisms that derive solely from the superhydrophobic nature of the coating. Moreover, unlike most of the superhydrophobic formulations, our system is fluorine-free, thus making the method eminently suitable for food and medical applications. The coating formulation is based on water in toluene or xylene emulsions that are stabilized using commercial hydrophobic silica, with polydimethylsiloxane (PDMS) dissolved in toluene or xylene. The structure of the emulsions and their stability was characterized by confocal microscopy and cryogenic-scanning electron microscopy (cryo-SEM). The most stable emulsions are applied on polypropylene (PP) surfaces and dried in an oven to form PDMS/silica coatings in a process called emulsion templating. The structure of the resulting coatings was investigated by atomic force microscopy (AFM) and SEM. The surface of the coatings shows a honeycomb-like structure that exhibits a combination of micron-scale and nanoscale roughness, which endows it with its superhydrophobic properties. After tuning, the superhydrophobic properties of the coatings demonstrated highly efficient passive antibiofilm activity. In vitro antibiofilm trials with E. coli indicate that the coatings reduced the biofilm accumulation by 83% in the xylene-water-based surfaces and by 59% in the case of toluene-water-based surfaces.

Non-wettable antibacterial thin film: PS/Aloe vera and PS/Acalypha indica

The water and liquid repelling materials due to their low surface energy and specific nanometer and micrometer scale roughness have particular interest due to the great variety of potential applications ranging from self-cleaning surfaces to microfluidic devices. Natural plant-based polymer hydrophobic coatings have several engineering and biomedical applications. In this study, natural plants such as Aloe vera and Acalypha indica were used for preparation of polystyrene hydrophobic film by the dip-coating method. The effects of Aloe vera and Acalypha indica extract on the morphological, structural, optical and antibacterial properties of as-prepared polystyrene thin films were studied. FTIR spectra were carried out to ascertain the presence of functional groups in the prepared polymeric film. Contact angle measurement showed that the PS/ Aloe vera has higher anti-wetting property (CA = 112°) compared to PS/ Acalypha indica (CA = 104°), which could be confirmed by the surface morphology analysis. Furthermore, the effective antibacterial activity against Klebsiella pneumoniae and Staphylococcus aureus was compared by agar-well diffusion method. The observed result reports, PS with Aloe vera film exhibit higher hydrophobic with antibacterial activity compared to PS with Acalypha indica film. In addition, the PS/ Aloe vera coated cotton maintained their repellent properties against various liquids for 10 h, while PS/ Acalypha indica coated cotton exhibit anti-wetting property for 4 h. These findings open up new avenues for the preparation of hydrophobic film for various biomedical applications.

Atomic Layer Deposition of Bioactive TiO2 Thin Films on Polyetheretherketone for Orthopedic Implants.

TiO2 thin films were deposited on the orthopedic implant material polyetheretherketone (PEEK) by plasma enhanced atomic layer deposition (PEALD) and characterized for their ability to enhance the osseointegrative properties. PEALD was chosen for film deposition to circumvent drawbacks present in line-of-sight deposition techniques, which require technically complex setups for a homogeneous coating thickness. Film conformality was analyzed on silicon 3D test structures and PEEK with micron-scale surface roughness. Wettability and surface energy were determined through contact angle measurements; film roughness and crystallinity were determined by atomic force microscopy and X-ray diffraction, respectively. Adhesion properties of TiO2 on PEEK were determined with tensile strength tests. Cell tests were performed with the mouse mesenchymal tumor stem cell line ST-2. TiO2-coated PEEK disks were used as substrates for cell proliferation tests and long-term differentiation tests. After 28 days of cultivation, a mineralized bone matrix was observed. Furthermore, the collagen I and osteocalcin content were determined. The results reveal that the osteogenic properties of the TiO2 thin film are comparable to those of hydroxyapatite, and thus bioactive properties of PEEK implants are improved by TiO2 thin films deposited with PEALD.

Effects of micrometer-scale surface roughness on thermal infrared emittance spectra of silica glass

Surface roughness is known to decrease thermal infrared (TIR) absorption band intensity, but studies of the effect on geologically relevant samples are relatively limited. To determine the effect of surface roughness (with features smaller than ~2/3 of the wavelength) on TIR spectra, we investigated two glass compositions with prepared roughened surfaces: (1) high purity fused silica and (2) soda-lime glass (73 wt% SiO2). We roughened the surfaces of the glasses by sandblasting and polishing with grit paper. The surfaces were characterized with scanning electron microscopy and stylus profilometry. We then analyzed the roughened glasses with TIR emittance spectroscopy. Micrometer-scale roughness causes a decrease in TIR absorption band intensity, relative to a specular surface. No significant changes in band shape or shifts in wavelength were detected. As roughness increases, empirical results show a logarithmic decrease in TIR absorption band intensity. The logarithmic trends of the two glass compositions are different; empirical roughness calibrations do not translate across different compositions. A linear, least-squares spectral deconvolution using two endmembers, specular and blackbody, predicts model spectra of roughened glass surfaces with relatively low error. This is of consequence to orbital TIR measurements of poorly constrained targets, such as the martian surface, because micrometer-scale roughness is adequately modeled by the addition of a blackbody spectrum to the deconvolution endmember matrix.

Analytical modeling of contact mechanics of helical gear tooth by considering surface roughness effects

Release of metal debris from a pair of gear teeth is a consequence of their contact. Any excessive metal debris can lead to the onset of fatigue and failure. This paper aims to derive a contact mechanics-based model to obtain the energy absorption of helical gear teeth. The proposed model includes the roughness effect of teeth contact surfaces. The mean value of the asperity summit curvature, the standard deviation of the asperity height distribution and the area density of the asperity height distribution are the three statistical parameters that describe the micron-scale surface roughness. An explicit approximation is obtained to relate the contact load and the minimum surface separation and to estimate the energy loss. Then an analytical expression is derived for the plastic energy dissipation per cycle as a function of plasticity index for gear teeth. The proposed function can be applied in the design of gears by engineers and manufacturers. Additionally, a pertinent lumped mass at the area of interaction is assumed to describe the contact frequency and damping ratio using a nonlinear dynamic model.

III–V Light-Emitting Diodes on Silicon by Hydrogel-Mediated Wafer Bonding

Monolithic on-chip integration of III–V compound semiconductor light-source components particularly on Si platforms is thought to be an important key technology in modern optoelectronics. Hydrogel-mediated semiconductor wafer bonding is an emerging technique for heterogeneous materials integration, simultaneously forming interfaces with high mechanical stability, electrical conductivity, optical transparency, and surface-roughness tolerance [K. Kishibe and K. Tanabe, Appl. Phys. Lett., 115, 081601 (2019)]. So far, its experimental demonstration has been limited to homogeneous Si/Si bonding and an application of solar-cell device. Here we demonstrate the fabrication and operation of a III–V light-emitting diode on Si, via heterogeneous GaAs/Si hydrogel-mediated wafer bonding. The bonding process is carried out in ambient air at room temperature, and therefore can potentially provide significant cost and throughput advantages in device production. Bonding with an unpolished back surface of semiconductor wafer with a micrometer-scale roughness is realized thanks to the deformability of hydrogel. The luminescence characteristics of the bonded device on Si are measured comparable to an unbonded reference. Stable operations of the device at over 70 °C and for over 100 h are demonstrated. Our experimental results verify the further suitability of the hydrogel-mediated semiconductor bonding scheme for optoelectronic device applications.

3D optical surface profiler for quantifying leaf surface roughness

Biological efficiency of pesticide droplets is affected by leaf surface fine structures; however, few reliable methods exist to physically measure and quantify surface roughness. A 3D optical surface profiler was evaluated for its effectiveness as a novel and reliable method to measure and quantify leaf surface roughness in terms of areal roughness parameters. Evaluations included its accuracy for measuring 3D roughness parameters relating mean roughness length, Sa, skewness, Ssk, and kurtosis, Sku. Their values were compared with the wettability of seven leaf types ranging from easy-to-wet to very difficult-to-wet. Measurement accuracy was validated by a qualitative visual analysis comparing 3D surface renderings of measured leaf surfaces generated by the profiler and micrographs taken with a scanning electron microscope (SEM). The accuracy was also validated by measuring and comparing the micrometer and sub-micrometer scaled roughness on leaf types with hierarchical (multi-scale) structuring and smooth surfaces. Both the renderings and the SEM showed visual agreement in surface variations from waxes and trichomes. The measured roughness lengths for the multi-scale and smooth surfaces were on the same order of magnitude for micrometer scale roughness, approximately 1×100 μm, but different orders of magnitude for sub-micrometer scale roughness, approximately 1×10−1 μm and 1×10−3 μm, respectively. Comparisons for Ssk and Sku to wettability were inconclusive, however, comparisons between Sa and wettability showed a positive linear fit, suggesting that Sa could be a viable metric for relating leaf surface roughness to wettability. The results from the micrometer and sub-micrometer scale surface roughness quantification could be used to improve pesticide spray deposition quality, leading to reductions in pesticide use and negative environmental impact.

An enhanced conformal contact modeling of the cylindrical roller bearings with inclusion of roughness effect

In this study, an enhanced analytical method is developed to obtain the energy loss during the loading-unloading interaction between roller bearing contact surfaces, in the presence of asperities. The macro-scale surface model considers the elastic-plastic interaction of the roller and outer ring. The micron-scale surface roughness parameters are defined based on three statistical parameters of the surface, which are the standard deviation of asperity height distribution, average asperity summit curvature and the density of asperities per unit area. The contact force induced by the interaction of rough surfaces is explicitly related to the minimum mean separation of surfaces. The energy loss in the bearing surfaces is then obtained using a numerical approximation and is related to the plasticity index, which is known to be a critical factor in the surface design of movement of the mechanical parts in contact. The developed model may assist manufactures to minimize the wear effect and risk of failure in roller bearing applications. Finally, for a lumped mass, assumed at the region of contact, the nonlinear vibration of the bearing system along with the identified contact force equation are utilized to estimate the contact natural frequency and damping ratio.

Wettability Control for Correct Thermophysical Properties Determination of Molten Salts and Their Nanofluids

Proper recording of thermophysical properties for molten salts (MSs) and molten salts based nanofluids (MSBNs) is of paramount importance for the thermal energy storage (TES) technology at concentrated solar power (CSP) plants. However, it is recognized by scientific and industrial communities to be non-trivial, because of molten salts creeping (scaling) inside a measuring crucible or a sample container. Here two strategies are proposed to solve the creeping problem of MSs and MSBNs for the benefit of such techniques as differential scanning calorimetry (DSC) and laser flash apparatus (LFA). The first strategy is the use of crucibles with rough inner surface. It was found that only nanoscale roughness solves the creeping problem, while micron-scale roughness does not affect the wetting phenomena considerably. The second strategy is the use of crucible made of or coated with a low-surface energy material. Both strategies resulted in contact angle of molten salt higher than 90° and as a result, repeatable measurements in correspondence to the literature data. The proposed methods can be used for other characterization techniques where the creeping of molten salts brings the uncertainty or/and unrepeatability of the measurements.

Contact of Rough Surfaces in Ankle Implants Under Combined Normal and Twist Loading

The medical application of implant replacements to remedy the pain in joints has necessitated a comprehensive study of wear due to contact of implant surfaces. Excessive wear can lead to toxicity and other implant associated medical issues such as patient discomfort and decreased mobility. Since implant wear is the result of contact between surfaces of tibia and talus implant, it is important to establish a model that can address implant surface contact mechanics with roughness effects. In this research, a statistical contact model is developed for the interaction of tibia and talus including normal and lateral contact in which surface roughness effects are included. The model accounts for the elastic–plastic interaction of the implant surface with roughness. For this purpose, tibia and talus implants are considered as macroscopic surfaces containing micron-scale roughness. Approximate equations are obtained that relate the contact force to the mean surface separation explicitly. Closed-form equations are obtained for hysteretic energy loss in implant using the approximate equations. Such a function can serve as a very useful tool for implant designers and manufacturers. Natural frequencies of both adduction-abduction and planter-dorsiflexion rotations are obtained using nonlinear vibration analyses.

Surface topography and cytocompatibility of metal injection molded Ti–22Nb alloy as biomaterial

Abstract Metal injection molding (MIM) was applied to fabricating Ti–22Nb (mass fraction, %) and commercially-pure Ti (CP-Ti, selected as reference) discs. As references, arc-melted and polished Ti–22Nb discs were employed. The surface topography and cytocompatibility were comparatively assessed on each configuration by microscopic analysis using confocal laser scanning microscopy and scanning electron microscopy and adhesion and viability tests. The results reveal that micron-scale roughness could be obtained via MIM process, and using blended Ti and Nb elemental powders instead of only Ti powder as raw materials leads to much higher surface roughness and surface area ratio. None of the three materials shows cytotoxicity, and the adhesion of human primary cells seems to be increased on the MIM Ti–22Nb specimens, especially around the closed-pores on the surface.

Mesenchymal Stem Cells Adhesion on Micro-to-Nano-Scaled Hierarchical Ti Implants Fabricated by Powder Metallurgy and Anodization

The osseointegration of titanium (Ti) implants highly depends on their surface properties, including roughness, wettability and composition. Ti surfaces with micron-scale roughness have demonstrated more rapid bone apposition compared with polished ones. Besides, Ti implants with nanostructured surface also exhibit better cell adhesion and proliferation behavior. However, the optimal surface for bone regeneration is still unknown, partly due to the difficulty in fabricating surfaces with highly reproducible micron-and nanotopography. In this study, Ti implants with two hierarchies of roughness were fabricated by powder metallurgy, followed by anodization treatment to obtain self-assembled TiO2 nanotubes on the micro-roughened surface. X-ray diffraction (XRD), scanning electron microscopy (SEM), 3D Laser Scanning Microscope (3D LSM), and fluorescence microscope were used to investigate the properties of the samples. Ra of the powder metallurgy surface was about 5 μm, while, nanotubes of around 100 nm in diameter were observed after the anodization process. Compared with the reference samples, i.e., the ones with either smooth or single-level-structure surfaces, the ones with micro-to-nanoscaled hierarchical topography exhibited lower contact angle, higher protein adsorption and significantly improved mesenchymal stem cells (MSCs) early adhesion.