Nanoscale Groove Research Articles

Tailoring zirconia surface topography via femtosecond laser-induced nanoscale features: effects on osteoblast cells and antibacterial properties

The performance and long-term durability of dental implants hinge on the quality of bone integration and their resistance to bacteria. This research aims to introduce a surface modification strategy for zirconia implants utilizing femtosecond laser ablation techniques, exploring their impact on osteoblast cell behavior and bacterial performance, as well as the integral factors influencing the soft tissue quality surrounding dental implants. Ultrafast lasers were employed to craft nanoscale groove geometries on zirconia surfaces, with thorough analyses conducted using x-ray diffraction, scanning electron microscopy, atomic force microscopy, and water contact angle measurements. The study evaluated the response of human fetal osteoblastic cell lines to textured zirconia ceramics by assessing alkaline phosphatase activity, collagen I, and interleukin 1βsecretion over a 7 day period. Additionally, the antibacterial behavior of the textured surfaces was investigated usingFusobacterium nucleatum, a common culprit in infections associated with dental implants. Ciprofloxacin (CIP), a widely used antibacterial antibiotic, was loaded onto zirconia ceramic surfaces. The results of this study unveiled a substantial reduction in bacterial adhesion on textured zirconia surfaces. The fine biocompatibility of these surfaces was confirmed through the MTT assay and observations of cell morphology. Moreover, the human fetal osteoblastic cell line exhibited extensive spreading and secreted elevated levels of collagen I and interleukin 1βin the modified samples. Drug release evaluations demonstrated sustained CIP release through a diffusion mechanism, showcasing excellent antibacterial activity against pathogenic bacteria, includingStreptococcus mutans, Pseudomonas aeruginosa, andEscherichia coli.

Study on wall-slipping mechanism of nano-injection polymer under the constant temperature fields

Abstract Polyphenylene sulfide (PPS) and copper (Cu) were used as the polymer and substrate material to simulate the nano-injection molding process by molecular dynamics method. The results show that the PPS chain obeys Einstein’s diffusion law in the early stage of injection molding then deviates from it in the late stage due to the entanglement and limitation of surrounding nanoparticles. In addition, the process of conformational isomerization of polymer chains is accompanied by the twisting and stretching of fixed chains. There are two kinds of adhesion phenomena, one is the macromolecular slides violently in small areas of some sure nanoscale groove to form multiple anchor points. The other case involves multiple nano-grooves along the metal interface, the polymer chain slides and is bolted as multiple anchors in different grooves due to the exerted wall-drag effect on the neighboring chains. These two slipping and anchoring mechanisms are consistent with de Gennes’ slipping theory. Through the quantitative analysis of the influence of pressure on injection filling, it is found that injection pressure should be kept within a certain range to achieve the positive effect of molding.

Chitosan from crab shell waste for soft lithography of bioplastic diffraction gratings.

Bioplastic diffraction gratings are fabricated from chitosan prepared from crab shells through a soft lithography replication process. Atomic force microscopy and diffraction experiments with the chitosan grating replicas indicate the successful copying of periodic nanoscale groove structures corresponding to densities of 600 and 1200lines/mm. First-order efficiency of bioplastic gratings is comparable to the output of elastomeric grating replicas.

Effect of Debye length scale surface features on electro-osmosis and its use to devise a novel electro-microfluidic separation

Numerically validated analytical predictions for electro-osmosis over a charged surface decorated with a nanoscale groove pattern are developed for the situation when the electrical double layer thickness is comparable to the spatial period of the grooves. For the analytical predictions, the groove shape can be specified by any continuous periodic function, such as the triangular, trapezoidal, and sinusoidal waveforms, which are investigated as special cases. We discover that the classical Helmholtz–Smoluchowski expression for electrokinetic mobility, notwithstanding its widespread use in measurements, is rendered invalid by the presence of Debye-length-scale unevenness in the surface topography. Furthermore, we use the depth-resolved anisotropic response of oblique grooves to design and optimize a novel electro-microfluidic strategy for separating constituents of a nano-particulate mixture.

Multidimensional Measurement of Electrical Coupling Properties of Nanostructured Substrates and Living Cells

The study of the electrical coupling properties of living cells and materials plays an important role in tissue engineering and clinical applications. The electrical coupling between living cells and substrates directly affects the growth, secretion and death of cells, as well as the measurement accuracy of electrophysiological parameters. In this work, the point contact model of the electrical coupling of cells and substrates is studied. It was found that the sealing impedance and effective contact area were the most important parameters affecting the electrical coupling. Moreover, the structure of nano-scale groove was fabricated by direct laser interference patterning (DLIP), and cylindrical arrays were fabricated on resist films after exposed to electron beam lithography (EBL). The two nanostructures were used as the substrates in vitro culture. The electrical coupling properties between living cells and structural substrates were discussed subsequently. In addition, the impedance spectrum of living cells at various frequencies, the relationship between the living cell number and impedance, and the impedance of living cells at different growth periods were measured. Furthermore, the multidimensional impedance information of living cells was obtained, and the impedance deviations between the two structure arrays were analyzed to evaluate the electrical coupling properties between the living cells and substrates. The proposed multidimensional impedance analysis method provides a way for studying the electrical coupling properties of nano-structured substrates and living cells.

Response of Human Blood Platelets on Nanoscale Groove Patterns: Implications for Platelet Storage

Understanding platelet–surface activation is of clinical importance because it directly involves the formation of a hemostatic plug or blood clot at sites of vascular injury. Although platelet activation on various structured patterns has been investigated, this behavior on nanoscale groove patterns remains unclear. Here, we fabricated pattern arrays with 100 and 500 nm groove sizes by electron-beam lithography and investigated the response of platelets on these patterns using scanning electron microscopy and atomic force microscopy. Without modification, platelets spread strongest on the unstructured surface and weakest on 100 nm grooves, while the spreading characteristic significantly decreased on laminin-modified surfaces. With a laminin coating, platelets did not spread after contact for 15 min, but the formation of filopodia of different lengths occurred, which is longest on the unstructured surface and shortest on 100 nm grooves. This difference correlated with the adhesion forces because the platelets bound strongest, weaker, and weakest on the corresponding unstructured surface and 500 and 100 nm nanopatterns. Our results show that platelet–surface activation depends on the underlying nanostructured surface, and the findings may have a major impact on medical applications.

Ruling engine using adjustable diamond and interferometric control for high-quality gratings and large echelles.

A concept for position adjustment of the diamond in a ruling engine to enable nanoscale groove positioning is proposed. Based on this concept, we fabricate a diamond carriage, design an optical path, and propose an appropriate control method. Several high-quality gratings are ruled for spectrometer or interferometer applications. After implementation of the improvements, the maximum intensity of ghosts and scattered light of the echelle grating with 79 grooves/mm is reduced to half of that before the improvement, and the highest achievable groove density is increased from 6000 grooves/mm to 8000 grooves/mm. The grating ruling results indicate that the proposed concept and the related improvements to the engine significantly improve the accuracy of the CIOMP-6 ruling engine.

Polymer spreading on substrates with nanoscale grooves using molecular dynamics

Understanding how liquid polymer interacts with and spreads on surfaces with nanoscale texture features is crucial for designing complex nanoscale systems. We use molecular dynamics to simulate different types of polymer as they spread on substrates with a single nanoscale groove. We study how groove design affects the potential energy of a substrate and how this governs polymer spreading and orientation. Based on our simulations, we show that groove shape, polymer chemistry, and polymer molecule entanglement are the three parameters that determine polymer spreading on a nanoscale groove. We provide a molecular-level explanation of the underlying physical mechanisms, and we illustrate this fundamental understanding by designing a network of grooves to engineer user-specified polymer spreading and coverage. This work has implications for nanoscale systems and devices that involve the design of complex groove networks with an ultrathin polymer coating, including micro and nanoelectromechanical devices, nanoimprint lithography, flexible electronics, antibiofouling coatings, and hard disk drives.

Nanoscale groove textured β-Ga2O3 by room temperature inverse metal-assisted chemical etching and photodiodes with enhanced responsivity

β-Ga2O3 is an emerging wide band-gap semiconductor that holds great promise for next generation power electronics and optoelectronics. β-Ga2O3 based ultraviolet photodetectors have been the subject of active research for the last few years. However, no micro and nanostructure surface texturing has been demonstrated for efficient light management in β-Ga2O3 optoelectronic applications yet. We hereby present nanoscale groove textured β-Ga2O3 metal-semiconductor-metal photodiodes, enabled by the unique metal-assisted chemical etching (MacEtch) method at room temperature in liquid. Although the textured surface stoichiometry shows ∼10% oxygen deficiency which results in a reduced Schottky barrier height and increased dark current, clear enhancement of the responsivity is demonstrated, compared to the planar untreated surface. The realization of MacEtch's applicability to β-Ga2O3 opens the door for producing more sophisticated device structures for this material, without resorting to conventional dry etch and potential damage.

Time-resolved measurement of single pulse femtosecond laser-induced periodic surface structure formation induced by a pre-fabricated surface groove.

Time-resolved diffraction microscopy technique has been used to observe the formation of laser-induced periodic surface structures (LIPSS) from the interaction of a single femtosecond laser pulse (pump) with a nano-scale groove mechanically formed on a single-crystal Cu substrate. The interaction dynamics (0-1200 ps) was captured by diffracting a time-delayed, frequency-doubled pulse (probe) from nascent LIPSS formation induced by the pump with an infinity-conjugate microscopy setup. The LIPSS ripples are observed to form asynchronously, with the first one forming after 50 ps and others forming sequentially outward from the groove edge at larger time delays. A 1-D analytical model of electron heating including both the laser pulse and surface plasmon polariton excitation at the groove edge predicts ripple period, melt spot diameter, and qualitatively explains the asynchronous time-evolution of LIPSS formation.

Effect of Machining Velocity in Nanoscale Machining Operations

The aim of this study is to investigate the generated forces and deformations of single crystal Cu with (100), (110) and (111) crystallographic orientations at nanoscale machining operation. A nanoindenter equipped with nanoscratching attachment was used for machining operations and in-situ observation of a nano scale groove. As a machining parameter, the machining velocity was varied to measure the normal and cutting forces. At a fixed machining velocity, different levels of normal and cutting forces were generated due to different crystallographic orientations of the specimens. Moreover, after machining operation percentage of elastic recovery was measured and it was found that both the elastic and plastic deformations were responsible for producing a nano scale groove within the range of machining velocities from 250-1000 nm/s.

J1640104 ランダムナノストライプ表面の形成と摩擦特性([J164-01]マイクロ・ナノ理工学:nmからmmまでの表面制御とその応用(1))

Surface pattern is expected the following effects in friction, such as generating dynamic pressure, supplying and preserving lubricate on oil and trapping wear particles. One of the authors has developed the nanostripe surface having nano-scale groove array that was formed by depositing two kinds of materials on micro-scale slope array and by polishing the surface. This report describes a method of fabricating irregular nano-scale grooves formed on a substrate having random asperities. The random asperities were fabricated on a stainless steel substrate by shot blast processing. Then friction tests were carried out using pin-on-plate type friction tester driven by a PZT actuator with magnification mechanism. The result showed that the friction coefficient of random nanostripe surface was lower than that of untextured surface in the boundary to mixed lubrication regime.

Scattering Intensity of Electric Field in Laser-Irradiated Nanoscale Groove

Scattering Intensity of Electric Field in Laser-Irradiated Nanoscale Groove

Holographic plasmonic lenses for surface plasmons with complex wavefront profile

We present a direct-method solution toward the general problem of plasmonic wavefront manipulation and shaping to realize pre-designated functionalities based on the surface-wave holography (SWH) method. We demonstrate theoretically and experimentally the design and fabrication of holographic plasmonic lenses over surface plasmons with complex wavefront profiles. We show that visible light at 632.8 nm transmitting through a high-aspect-ratio slit or a micro-rectangle hole in a silver film can be focused to a preset three-dimensional point spot in free space via appropriately manipulating the interaction of excited surface plasmons with the nanoscale groove pattern of the holographic lens. The experiment results of scanning near-field optical microscopy for measuring the three-dimensional optical field distribution agree well both with designs and with numerical simulations, and this strongly supports the effectiveness and efficiency of the SWH method in the design of plasmonic devices that can fulfill manipulation and transformation of complicated-profile surface plasmons.

Determination of surface nematic liquid crystal anchoring strength using nano-scale surface grooves

Based on several nano-scale groove models, we propose a new technique to simultaneously determine the azimuthal and polar surface anchoring strengths of nematic liquid crystal (LC). The optical analysis of LCs on a grooved surface made by nanoimprinting lithography was performed on special alignment material, using a typical rubbing process. In our approach, using a polarizing microscope, we can determine the LC alignment exactly as it is in a parallel state, rather than a twisted state. This simple proposed method gives an accurate value of the surface LC anchoring of various surfaces, as well as simultaneously measuring the azimuthal and polar anchoring energy.

Mechanism of Abrasive Wear in Nanomachining

In this study, nanomachining is utilized to investigate the abrasive wear mechanism that produces a nano scale groove on a bulk material. Two different tools (Berkovich and Conical) with the same tip radius (100 nm) but different edge geometries were used for machining both Cu- and Ni-coated materials with a nanoindenter that was equipped with a nano scratching attachment. It was found that the generated forces (normal and cutting) increased with the increase of depth of cut; however, the generated normal force at the minimum depth of cut (50 nm) was more than the critical force for all machining conditions. Therefore, at the minimum depth of cut, groove formation started with the ploughing mode of abrasive wear mechanism, then the cutting mechanism activated along with the ploughing mechanism above a 100 nm depth of cut. The percentage values of these two mechanisms were determined and utilized to determine the dominant mode of the abrasive wear mechanism for producing a nano scale groove on a metal surface and, to correlate this, abrasive wear mechanism with the co-efficient of friction (μ) at different machining conditions. The results also showed that the co-efficient of friction (μ) increased when ploughing was the dominant mode of abrasive wear mechanism to produce a nano scale groove. Thus, μ was found to be proportional to the ploughing mode of abrasive wear mechanism in nanomachining.

Three-Dimensional Hierarchical Structures for Fog Harvesting

Conventional fog-harvesting mechanisms are effectively pseudo-2D surface phenomena in terms of water droplet-plant interactions. In the case of the Cotula fallax plant, a unique hierarchical 3D arrangement formed by its leaves and the fine hairs covering them has been found to underpin the collection and retention of water droplets on the foliage for extended periods of time. The mechanisms of water capture and release as a function of the surface 3D structure and chemistry have been identified. Of particular note is that water is retained throughout the entirety of the plant and held within the foliage itself (rather than in localized regions). Individual plant hairs form matlike structures capable of supporting water droplets; these hairs wrap around water droplets in a 3D fashion to secure them via a fine nanoscale groove structure that prevents them from easily falling to the ground.

The mechanics of single crystal Cu machining at nanoscale

The objective of this study is to identify the mechanics of machining at nano scale on single crystal Cu with (100), (110) and (111) crystallographic orientations. A nano indenter equipped with a nano scratching attachment was used for machining operations and in situ observation of a nano scale groove. As a machining parameter, the depth of cut was varied in this study. Both elastic and plastic deformations were significant during machining. The plastic deformation was responsible for causing the ploughing and cutting mechanisms to produce the nano scale groove. The presence of the ploughing and cutting g mechanisms was determined based on the pile up volume and the cutting volume respectively.

Study of Abrasive Wear Mechanism through Nano Machining

The objective of this paper is to understand the abrasive wear mechanism for producing a nano scale groove on a bulk material through nano machining. A nano indenter equipped with a nano scratching attachment was used for nano machining operation and in situ observation of the machined surfaces. Two different tools (Berkovich and Conical) with the same tip radius (100nm) but different edge geometries were used to machine both Copper and Nickel coatings. It was found that the percentage of elastic recovery was lower for Cu than Ni during this nano machining operations. Hence, the deformation mechanism in nano machining operation was identified as elasto-plastic in nature as opposed to the well established completely plastic mode of conventional machining operations. The pile up volume due to plastic deformation was utilized to distinguish between the ploughing and cutting modes of abrasive wear mechanisms. The results reveal that the ploughing mechanism was dominant for Cu and the cutting mechanism was dominant for Ni machining. Moreover, both mechanisms ploughing and cutting were the dominant modes of abrasive wear using the Berkovich tip compared to the Conical tip for producing a nano scale groove through nano machining.

Investigation of deformation behaviour and abrasive wear mechanism in nanomachining

The aim of this study is to investigate the deformation behaviour and the abrasive wear mechanism of copper and nickel materials in nanomachining. A nanoindenter equipped with a nanoscratching attachment was used for nanomachining and in situ observation of the machined surfaces. The results showed that the generated normal and cutting forces were higher for Ni than for Cu machining. However, the elastic recovery (%) was lower for Cu than for Ni. Hence, both elastic and plastic deformations were significant in these machining conditions. The pile-up volume due to plastic deformation distinguished between the ploughing and cutting mechanisms. The ploughing mechanism was dominant for Cu machining, while the cutting mechanism was dominant for Ni machining. When the depth of cut was smaller than the cutting tool tip radius, only the ploughing mechanism contributed, otherwise, both mechanisms contributed to produce a nanoscale groove.