3D Topography Research Articles

3D surface topography prediction in the five-axis milling of plexiglas and metal using cutters with non-uniform helix and pitch angles combining runout

3D surface topography prediction in the five-axis milling of plexiglas and metal using cutters with non-uniform helix and pitch angles combining runout

The Development of 3D Atomic Force Microscopy with Magnetically Driven-Orthogonal Cantilever Probes

This paper presents a three-dimensional (3D)-atomic force microscopy (AFM) method based on magnetically driven (MD)-orthogonal cantilever probes (OCPs), in which two independent scanners with three degrees of freedom are used to achieve the vector tracking of a sample surface with a controllable angle. A rotating stage is integrated into the compact AFM system, which helps to achieve 360° omnidirectional imaging. The specially designed MD-OCP includes a horizontal cantilever, a vertical cantilever, and a magnetic bead that can be used for the mechanical drive in a magnetic field. The vertical cantilever, which has a protruding tip, can detect deep grooves and undercut structures. The design, simulation, fabrication, and performance analysis of the MD-OCP are described first. Then, the amplitude compensation and home positioning for 360° rotation are introduced. A comparative experiment using an AFM step grating verifies the ability of the proposed method to characterize steep sidewalls and corner details, with a 3D topography reconstruction method being used to integrate the images. The effectiveness of the proposed 3D-AFM based on the MD-OCP is further confirmed by the 3D characterization of a micro-electromechanical system (MEMS) device with microcomb structures. Finally, this technique is applied to determine the critical dimensions (CDs) of a microarray chip. The experimental results regarding the CD parameters show that, in comparison with 2D technology, from which it is difficult to obtain sidewall information, the proposed method can obtain CD information for 3D structures with high precision and thus has excellent potential for 3D micro–nano manufacturing inspection.

Structural Analysis and Hydrophilic Behavior of Co3O4 Thin Film for Enhanced Photocatalytic Activity under Visible Light with Hole Scavengers

This research presents a cost-effective sol-gel technique to produce a uniform and highlyeffective Co3O4 thin film on glass substrates with a withdrawal speed of 5 m/s. The surface morphologyand roughness of the film were analyzed, and it demonstrated a thickness of 177 nm and band gap of 2.0eV. Under solar irradiation, the thin film exhibited remarkable photocatalytic degradation efficacy, with ahigh efficiency of 78% for blue methylene (BM). The 3D surface topography scan indicated significantroughness at 54.7 nm. Hole-scavengers such as H2O2, EDTA, and Octan-1 were found to enhance BMdegradation. The study highlights the potential of the Co3O4 thin film for treating various organiccontaminants in wastewater from diverse sources under solar irradiation.

Multispectral Imaging for Skin Diseases Assessment-State of the Art and Perspectives.

Skin optical inspection is an imperative procedure for a suspicious dermal lesion since very early skin cancer detection can guarantee total recovery. Dermoscopy, confocal laser scanning microscopy, optical coherence tomography, multispectral imaging, multiphoton laser imaging, and 3D topography are the most outstanding optical techniques implemented for skin examination. The accuracy of dermatological diagnoses attained by each of those methods is still debatable, and only dermoscopy is frequently used by all dermatologists. Therefore, a comprehensive method for skin analysis has not yet been established. Multispectral imaging (MSI) is based on light-tissue interaction properties due to radiation wavelength variation. An MSI device collects the reflected radiation after illumination of the lesion with light of different wavelengths and provides a set of spectral images. The concentration maps of the main light-absorbing molecules in the skin, the chromophores, can be retrieved using the intensity values from those images, sometimes even for deeper-located tissues, due to interaction with near-infrared light. Recent studies have shown that portable and cost-efficient MSI systems can be used for extracting skin lesion characteristics useful for early melanoma diagnoses. This review aims to describe the efforts that have been made to develop MSI systems for skin lesions evaluation in the last decade. We examined the hardware characteristics of the produced devices and identified the typical structure of an MSI device for dermatology. The analyzed prototypes showed the possibility of improving the specificity of classification between the melanoma and benign nevi. Currently, however, they are rather adjuvants tools for skin lesion assessment, and efforts are needed towards a fully fledged diagnostic MSI device.

Tracking metal enhanced fluorescence from Eschericcia coli nano-bio-assemblies within colloidal dispersions by static and 3D spectra emissions

It was studied the interactions of single Ultraluminescent 40 nm gold Core shell Nanoparticles (d40 Au@SiO2-Fl) with Eschericcia Coli bacteria (Esc. Col). By this manner, it was tracked from initial Nano-Bio-assembly formation (Au@SiO2-Fl-Esc. Col) towards inter-Nano-Biostructure interactions. In order to do that it was determined association constants between d40 Au@SiO2-Fl and Biostructures by 3D Fluorescence, fluorescence spectroscopy measurements. The association constant was related with non-covalent Nano-Biostructure interactions of 45 ± 2 biostructure-1; accompanied with a Quantum Yield ratio between the Bio-assembly and Nano-labeller of 3.6 ± 0.1 times, with the maximal concentration of bacteria addition. This phenomenon of interaction was tracked from the bulk of the colloidal dispersion. And, from these individual interactions, it was possible to generate Bioimaging by Laser Fluorescence Microscopy in real time of the dynamic of Bio-assembly formation as well as the by inter-Nano-Biostructures. These data leaded to the correlation of 3D Fluorescence spectroscopy within different bacteria concentrations. The recorded spectra showed increased values of intensities that fitted to a linear equation as model of the experimental data records. About analytical performances, it could be noted that optimized sensitivity by 3D Fluorescence was unless 65% higher than by static Fluorescence. Moreover, it should be mentioned that two distributions of emissions were recorded that correlated with Plasmonics coupling with natural emitters within the UV and MEF Nanolabeller emissions. Thus, optimizing conditions, LODs of 0.3x10 3 bacterium*mL−1 were determined. Moreover, by In Flow Cytometry was recorded different sensitivity values depending of the Laser excitation applied. These phenomena were explained by the development of different Nano-Bio-emitters species. In addition, in order to validate the methodology, it was quantified Biostructures from fortified aqueous samples. By 3D Fluorescence it was determined recoveries of (97 ± 8)x103, and (93 ± 5)x103 from upper and lower distributions of emissions recorded in 3D Fluorescence topographies. The reproducibility in all cases was by %CV of 98–99 %; therefore the proposed Bioassays showed interesting insights in Nano-Biotechnology with impact in varied Research fields.In this way, it was showed and discussed about Bio-analytical applications for Eschericcia Coli detection and quantification within colloidal dispersion with relative simple, accessible and portable fluorescence spectroscopy set ups. Therefore, it was given insights for accessible Nano-Biodetection based on Ultra-sensitive MEF Nanoplatforms for Bio-labeling using standard spectroscopic and compared by In Flow Citometry analysis as well.

Towards understanding Shewanella algae-induced degradation of passive film of stainless steel based on electrochemical, XPS and multi-mode AFM analyses

The degradation of the passive film of stainless steel caused by Shewanella algae was investigated through electrochemical tests, X-ray photoelectron spectroscopy and atomic force microscopy (AFM). The dynamic mode and the nano manipulation mode of AFM were adopted to obtain the 3D topography of cell/passive film interfaces and to manipulate cell movement, respectively. The surface Volta potential scanning by tapping-amplitude modulation mode and the conductivity tests by PeakForce-TUNA mode of AFM revealed the electron injection phenomenon from S. algae cells into adjacent passive film, which promoted the reduction of Fe3+ compounds and accelerated the degradation of passive film.

Tool–workpiece separation characteristic and surface generation in ultrasonic assisted milling

Ultrasonic assisted machining is an eco-friendly surface texture fabrication method with low machining cost, high-accuracy precision, and efficiency. This study analyzes the surface texture formation in feed direction ultrasonic vibration assisted milling (FUVAM) and elliptical ultrasonic vibration assisted milling (EUVAM). The trajectories of the single and adjacent tool tips in FUVAM are analyzed. Furthermore, the tool–workpiece separation mechanism in EUVAM is discussed. Moreover, a 3D surface topography model of EUVAM is applied to study the influences of machining parameters on the ultrasonic machining topography. The experiments of conventional milling (CM) and EUVAM are carried out and different types of surface textures are successfully fabricated on Ti-6Al-4V using EUVAM. The results of the response surface indicate that the surface roughness shows an increasing trend with higher spindle speed, but decreases with improved feed speed and cutting depth. Compared with CM, the chips generated in EUVAM have the characteristics of small width and low bending degree. This work is expected to provide some guidance for the selection of machining and vibration parameters during ultrasonic assisted milling.

Effects of complex terrain on the shortwave radiative balance: a sub-grid-scale parameterization for the GFDL Earth System Model version 4.1

Abstract. Parameterizing incident solar radiation over complex topography regions in Earth system models (ESMs) remains a challenging task. In ESMs, downward solar radiative fluxes at the surface are typically computed using plane-parallel radiative transfer schemes, which do not explicitly account for the effects of a three-dimensional topography, such as shading and reflections. To improve the representation of these processes, we introduce and test a parameterization of radiation–topography interactions tailored to the Geophysical Fluid Dynamics Laboratory (GFDL) ESM land model. The approach presented here builds on an existing correction scheme for direct, diffuse, and reflected solar irradiance terms over three-dimensional terrain. Here we combine this correction with a novel hierarchical multivariate clustering algorithm that explicitly describes the spatially varying downward irradiance over mountainous terrain. Based on a high-resolution digital elevation model, this combined method first defines a set of sub-grid land units (“tiles”) by clustering together sites characterized by similar terrain–radiation interactions (e.g., areas with similar slope orientation, terrain, and sky view factors). Then, based on terrain parameters characteristic for each tile, correction terms are computed to account for the effects of local 3D topography on shortwave radiation over each land unit. We develop and test this procedure based on a set of Monte Carlo ray-tracing simulations approximating the true radiative transfer process over three-dimensional topography. Domains located in three distinct geographic regions (Alps, Andes, and Himalaya) are included in this study to allow for independent testing of the methodology over surfaces with differing topographic features. We find that accounting for the sub-grid spatial variability of solar irradiance originating from interactions with complex topography is important as these effects led to significant local differences with respect to the plane-parallel case, as well as with respect to grid-cell-scale average topographic corrections. We further quantify the importance of the topographic correction for a varying number of terrain clusters and for different radiation terms (direct, diffuse, and reflected radiative fluxes) in order to inform the application of this methodology in different ESMs with varying sub-grid tile structure. We find that even a limited number of sub-grid units such as 10 can lead to recovering more than 60 % of the spatial variability of solar irradiance over a mountainous area.

Microstructured click hydrogels for cell contact guidance in 3D.

The topography of the extracellular matrix (ECM) is a major biophysical regulator of cell behavior. While this has inspired the design of cell-instructive biomaterials, the ability to present topographic cues to cells in a true 3D setting remains challenging, particularly in ECM-like hydrogels made from a single polymer. Herein, we report the design of microstructured alginate hydrogels for injectable cell delivery and show their ability to orchestrate morphogenesis via cellular contact guidance in 3D. Alginate was grafted with hydrophobic cyclooctyne groups (ALG-K), yielding amphiphilic derivatives with self-associative potential and ionic crosslinking ability. This allowed the formation of microstructured ALG-KH hydrogels, triggered by the spontaneous segregation between hydrophobic/hydrophilic regions of the polymer that generated 3D networks with stiffer microdomains within a softer lattice. The azide-reactivity of cyclooctynes also allowed ALG-K functionalization with bioactive peptides via cytocompatible strain-promoted azide-alkyne cycloaddition (SPAAC). Hydrogel-embedded mesenchymal stem cells (MSCs) were able to integrate spatial information and to mechano-sense the 3D topography, which regulated cell shape and stress fiber organization. MSCs clusters initially formed on microstructured regions could then act as seeds for neo-tissue formation, inducing cells to produce their own ECM and self-organize into multicellular structures throughout the hydrogel. By combining 3D topography, click functionalization, and injectability, using a single polymer, ALG-K hydrogels provide a unique cell delivery platform for tissue regeneration.

Multiresponse optimization of performance indicators through Taguchi-grey relational analysis in EDM of cemented carbide

Cemented carbide is mostly used in the mold and tool industry due to their high hardness, temperature and wear resistance, and it is very difficult to shape with conventional machining methods. Because, during the machining of certain geometry from these materials, microcracks on surface and flaking at the machined edges due to their brittleness as well as rapid tool wear mostly due to their high hardness occur. In this case, EDM is considered one of the most suitable machining technologies for brittle material such as carbides, as it provides a non-contact shaping with electrical sparks between the tool and the workpiece. This study focused on the simultaneous optimization of the most important performance indicators namely material removal rate, tool wear rate and surface roughness in creating a keyway on WC-15Co material with the die-sinking EDM. As a result of experiments using copper electrode, the impacts on performance indicators of discharge current, pulse time and pulse interval were investigated with 3D surface topography images. It was determined that the peaks and craters formed on the machined surface expanded with the increase of pulse time, and the decreased with the increase in the pulse interval. As a result of the Taguchi-grey relational analysis (TGRA) application, discharge current of 6 A, pulse time of 25 µs and pulse interval of 100 µs were found as optimum parameters. ANOVA results showed that Ip, Ton and Toff affected GRG values by 44.23%, 28.77% and 5.87%, respectively. A 23.95% improvement in performance indicators was achieved thanks to the TGRA multiresponse optimization.

Applications of Chromatic Confocal Technology in Precision Geometric Measurement of Workpieces

Chromatic confocal technology is increasingly applied in industries that require high-precision geometric measurements such as aerospace, naval ordnance, and medical electronics owing to its advantages in testing accuracy, real-time performance, anti-interference, and no damage to tested workpieces. This paper introduces the measurement principle of chromatic confocal technology and the structure of chromatic confocal sensors, and enumerates several typical application scenarios of the technology from the aspects of thickness measurement, profile, 3D topography scanning, roughness measurement, and wafer comprehensive parameter measurement. It also looks into potential development directions of chromatic confocal technology.

Identification of gear wear damage using topography analysis

Gear failure modes and their underlying mechanisms are usually identified by visual inspection, which relies on the skills and experience of the human observer and hence is prone to subjectivity and bias. Therefore, it is essential to design and implement objective methods to improve the identification of gear failure modes. In the present study, the 3D topography of gear surfaces affected by different types of wear modes, i.e., micropitting, pitting, and scuffing, was measured by means of white light interferometry. The surfaces were evaluated in terms of height, spatial, and function roughness parameters, according to ISO 25178-2. Besides, a new roughness parameter, named surface motion orientation (Smo), was proposed. Three features were found relevant to identify the differences between the gear surfaces affected by different failure modes: the shape of asperities distribution, the severity of damage, and the surface texture orientation with respect to the motion direction. The combination of the roughness parameters selected to quantify each of these features (Ssk,Sq,Smo) resulted in an objective classification of the assessed gear failure modes.

Digital Fringe Projection-Based Clamping Force Estimation Algorithm for Railway Fasteners

The inspection of railway fasteners to assess their clamping force can be used to evaluate the looseness of the fasteners and improve railway safety. Although there are various methods for inspecting railway fasteners, there is still a need for non-contact, fast inspection without installing additional devices on fasteners. In this study, a system that uses digital fringe projection technology to measure the 3D topography of the fastener was developed. This system inspects the looseness through a series of algorithms, including point cloud denoising, coarse registration based on fast point feature histograms (FPFH) features, fine registration based on the iterative closest point (ICP) algorithm, specific region selection, kernel density estimation, and ridge regression. Unlike the previous inspection technology, which can only measure the geometric parameters of fasteners to characterize the tightness, this system can directly estimate the tightening torque and the bolt clamping force. Experiments on WJ-8 fasteners showed a root mean square error of 9.272 N·m and 1.94 kN for the tightening torque and clamping force, demonstrating that the system is sufficiently precise to replace manual measurement and can substantially improve inspection efficiency while evaluating railway fastener looseness.

Parallel unambiguous generalized phase-shifting and T-spline fitting algorithms for optical micro-structured surface 3D topography metrology.

3D topography metrology of optical micro-structured surfaces is critical for controlled manufacturing and evaluation of optical properties. Coherence scanning interferometry technology has significant advantages for measuring optical micro-structured surfaces. However, the current research faces difficulties of designing high accuracy and efficient phase shifting, and characterization algorithms for optical micro-structured surface 3D topography metrology. In this paper, parallel unambiguous generalized phase-shifting and T-spline fitting algorithms are proposed. To avoid phase ambiguity and improve the accuracy of the phase-shifting algorithm, the zero-order fringe is determined by the iterative envelope fitting with Newton's method, and the accurate zero optical path difference is determined by a generalized phase-shifting algorithm. In particular, the calculation procedures of the multithreading iterative envelope fitting with Newton's method and generalized phase shifting are optimized with the graphics processing unit-Compute Unified Device Architecture kernel function. Additionally, to fit the base form of optical micro-structured surfaces and characterize the surface texture and roughness, an effective T-spline fitting algorithm is proposed by optimizing the preimage of the T-mesh with image quadtree decomposition. Experimental results show that the surface reconstruction of optical micro-structured surfaces using the proposed algorithm is more accurate, and the efficiency is 10 times higher than that of current algorithms; the time of the surface reconstruction is less than 1s. Compared with the current B-spline method, the accuracy of roughness characterization using the proposed T-spline algorithm is improved by more than 10%.

Parallelized computational 3D video microscopy of freely moving organisms at multiple gigapixels per second.

Wide field of view microscopy that can resolve 3D information at high speed and spatial resolution is highly desirable for studying the behaviour of freely moving model organisms. However, it is challenging to design an optical instrument that optimises all these properties simultaneously. Existing techniques typically require the acquisition of sequential image snapshots to observe large areas or measure 3D information, thus compromising on speed and throughput. Here, we present 3D-RAPID, a computational microscope based on a synchronized array of 54 cameras that can capture high-speed 3D topographic videos over an area of 135 cm2, achieving up to 230 frames per second at spatiotemporal throughputs exceeding 5 gigapixels per second. 3D-RAPID employs a 3D reconstruction algorithm that, for each synchronized snapshot, fuses all 54 images into a composite that includes a co-registered 3D height map. The self-supervised 3D reconstruction algorithm trains a neural network to map raw photometric images to 3D topography using stereo overlap redundancy and ray-propagation physics as the only supervision mechanism. The resulting reconstruction process is thus robust to generalization errors and scales to arbitrarily long videos from arbitrarily sized camera arrays. We demonstrate the broad applicability of 3D-RAPID with collections of several freely behaving organisms, including ants, fruit flies, and zebrafish larvae.

The Effect of Cutting Tool Geometry on Surface Integrity: A Case Study of CBN Tools and the Inner Surface of Bearing Rings

In this paper, a practical issue of the application of cubic boron nitride (CBN) cutting tools for the machining of steel 100Cr6 thin-walled bearing rings is addressed. Three geometries of the commercially available CBN cutting inserts were tested at different machining parameters. The effect of geometry was assessed in terms of surface integrity, considering 2D profile parameters, 3D topography of the surface, and residual stresses in the surface layer. The results were sometimes contradictory, since the same cutting inserts provided the largest and the lowest values of the topography parameters, dependent on different cutting conditions. In general, CBN cutting inserts with XCEL geometry ensured the smallest profile parameters Ra and Rz, and the spatial parameters of Smr1 exhibited the largest values among all tested tools, suggesting reduced wear resistance. Residual stresses analysis did not reveal any inacceptable or potentially dangerous surface layer state after machining.

A Multivariate Local Descriptor Registration Method for Surface Topography Evaluation

This paper illustrates a systematical surface topography measurement and evaluation method based on a 3D optical system. Firstly, the point cloud data of the workpiece are extracted by the use of a 3D structured light measurement system, and the STEP file of the design model is converted into point cloud data. Secondly, the local measurement point cloud (LMPC) and digital model point cloud (DMPC) are registered by a multivariate local descriptor registration scheme proposed in this study. Thirdly, the surface shapes extracted from the STEP file are applied as a reference to segment the measuring point cloud. Finally, an error analysis scheme is conducted on specific functional surfaces. An experiment was conducted to analyse the flatness, cylindricity and roughness to demonstrate the effectiveness and advantage of the method. The comparison results show that the proposed method outperforms other 3D optical surface topography analysis methods.

Mechanical and Tribological Performance of HDPE Matrix Reinforced by Hybrid Gr/TiO2 NPs for Hip Joint Replacement.

Hip joint collapse is a very common health problem. Many cases need a joint replacement, so nano-polymeric composites are an ideal alternative solution. Due to its mechanical properties and wear resistance, HDPE might be considered a suitable alternative to frictional materials. The current research focuses on using hybrid nanofiller TiO2 NPs and nano-graphene with various loading compositions to evaluate the best loading amount. The compressive strength, modules of elasticity, and hardness were examined via experiments. The COF and wear resistance were evaluated via a pin-on-disk tribometer. The worn surfaces were analyzed based on 3D topography and SEM images. The HDPE samples with various compositions of 0.5%, 1.0%, 1.5%, and 2.0 wt.% filling content of TiO2 NPs and Gr (with a ratio of 1:1) were analyzed. Results revealed that hybrid nanofiller with a composition of 1.5 wt.% exhibits superior mechanical properties compared to other filling compositions. Moreover, the COF and wear rate decreased by 27.5% and 36.3%, respectively.

Profilometry and atomic force microscopy for surface characterization

<sec><strong>Aim</strong> This study aims to evaluate and compare the profilometry and atomic force microscopy (AFM) for characterization of biomaterial surfaces. </sec><sec><strong>Method</strong> The clinically commonly used titanium (Ti) was used as the specimen. Each of the specimen was prepared by different grits of sandpapers, including 2000, 1000, 800, 600, 400, 220, 180, and 100 grits. An unpolished Ti plate served as the control. Surface characterization of the Ti specimens was examined using profilometry and AFM. </sec><sec><strong>Results</strong> Both profilometry and AFM were capable of producing two-dimensional (2D) and three-dimensional (3D) topography. The scanning speed of profilometry (12 ± 5 s/image) was faster than that of AFM (250 ± 50 s/image) (<i>p</i> &lt; 0.01). The resolution of AFM was relatively higher than profilometry. AFM produced more precise value, especially at nano-scale. When the Ti surface roughness was less than 0.2 μm, the results of surface roughness measured by profilometry and AFM were similar (mean difference = 0.01 ± 0.03, <i>p</i> = 0.81). When the Ti surface roughness was more than 0.3 μm, the surface roughness measured by profilometry was slightly higher than that by AFM (mean difference = 0.43 ± 0.15, <i>p</i> = 0.04). </sec><sec><strong>Conclusion</strong> Profilometry and AFM are both useful techniques for the characterization of biomaterial surfaces. Profilometry scanned faster than the AFM but produced less detailed surface topography. Both technologies provided similar measurement when the roughness was less than 0.2 μm. When the Ti surface roughness was more than 0.3 μm, the surface roughness measured by profilometry was slightly higher than that by AFM. </sec>

Gut-on-a-chip models for dissecting the gut microbiology and physiology.

Microfluidic technologies have been extensively investigated in recent years for developing organ-on-a-chip-devices as robust in vitro models aiming to recapitulate organ 3D topography and its physicochemical cues. Among these attempts, an important research front has focused on simulating the physiology of the gut, an organ with a distinct cellular composition featuring a plethora of microbial and human cells that mutually mediate critical body functions. This research has led to innovative approaches to model fluid flow, mechanical forces, and oxygen gradients, which are all important developmental cues of the gut physiological system. A myriad of studies has demonstrated that gut-on-a-chip models reinforce a prolonged coculture of microbiota and human cells with genotypic and phenotypic responses that closely mimic the in vivo data. Accordingly, the excellent organ mimicry offered by gut-on-a-chips has fueled numerous investigations on the clinical and industrial applications of these devices in recent years. In this review, we outline various gut-on-a-chip designs, particularly focusing on different configurations used to coculture the microbiome and various human intestinal cells. We then elaborate on different approaches that have been adopted to model key physiochemical stimuli and explore how these models have been beneficial to understanding gut pathophysiology and testing therapeutic interventions.