Search Results (363)

This paper investigates the nonlinear bending analysis of nano-beams using the physics-informed neural network (PINN) method. The nonlinear governing equations for the bending of size-dependent nano-beams are derived from Hamilton’s principle, incorporating nonlocal strain gradient theory, and based on Euler–Bernoulli beam theory. In the PINN method, the solution is approximated by a deep neural network, with network parameters determined by minimizing a loss function that consists of the governing equation and boundary conditions. Despite numerous reports demonstrating the applicability of the PINN method for solving various engineering problems, tuning the network hyperparameters remains challenging. In this study, a systematic approach is employed to fine-tune the hyperparameters using hyperparameter optimization (HPO) via Gaussian process-based Bayesian optimization. Comparison of the PINN results with available reference solutions shows that the PINN, with the optimized parameters, produces results with high accuracy. Finally, the impacts of boundary conditions, different loads, and the influence of nonlocal strain gradient parameters on the bending behavior of nano-beams are investigated. Full article

Nanoscale zinc sulfide (ZnS) powders have attracted considerable interest due to their unique properties and diverse applications in various fields, including wastewater treatment, optics, electronics, photocatalysis, and solar systems. In this study, nano-powder ZnS was chemically synthetized starting from Zn powder, diluted HCl, and laboratory-prepared Na2S. The obtained ZnS was studied using an SEM coupled with EDS, XRD analysis, UV–Visible spectroscopy, and FTIR techniques. The XRD results showed that the synthesized nanoscale ZnS powder was approximately 2.26 nm. Meanwhile, the EDS and XRD patterns confirmed the high purity of the obtained ZnS powder. In addition, the ZnS powder was compacted and sintered in an argon atmosphere at 400 °C for 8 h to prepare the required pellets for thin-film deposition via E-beam evaporation. The microscopic structure of the sintered pellets was investigated using the SEM/EDS. Furthermore, the optical properties of the deposited thin films were studied using UV–Visible spectroscopy in the wavelength range of 190–1100 nm and the FTIR technique. The bandgap energies of the deposited thin films with thicknesses of 111 nm and 40 nm were determined to be around 4.72 eV and 5.82 eV, respectively. This article offers a facile production route of high-purity ZnS powder, which can be compacted and sintered as a suitable source for thin-film deposition. Full article

The enduring manufacturing goals are increasingly shifting toward ultra-precision manufacturing and micro-nano fabrication, driven by the demand for sophisticated products. Unconventional machining processes such as electrochemical jet machining (ECJM), electrical discharge machining (EDM), electrochemical machining (ECM), abrasive water jet machining (AWJM), and laser beam machining (LBM) have been widely adopted as feasible alternatives to traditional methods, enabling the production of high-quality engineering components with specific characteristics. ECJM, a non-contact machining technology, employs electrodes on the nozzle and workpiece to establish an electrical circuit via the jet. As a prominent special machining technology, ECJM has demonstrated significant advantages, such as rapid, non-thermal, and stress-free machining capabilities, in past research. This review is dedicated to outline the research progress of ECJM, focusing on its fundamental concepts, material processing capabilities, technological advancements, and its variants (e.g., ultrasonic-, laser-, abrasive-, and magnetism-assisted ECJM) along with their applications. Special attention is given to the application of ECJM in the semiconductor and biomedical fields, where the demand for ultra-precision components is most pronounced. Furthermore, this review explores recent innovations in process optimization, significantly boosting machining efficiency and quality. This review not only provides a snapshot of the current status of ECJM technology, but also discusses the current challenges and possible future improvements of the technology. Full article

Reinforced concrete structures are prone to the development of microcracks during service. In this study, a composite-modified epoxy potting adhesive was formulated using nano-TiO₂, carboxyl-terminated butadiene nitrile liquid rubber (CTBN), and the reactive diluent D-669. The mechanical properties and effectiveness of this composite adhesive in repairing oblique cracks were systematically evaluated and compared with those of single-component-modified epoxy adhesives. Key material parameters influencing the performance of oblique crack repair were identified, and the underlying repair mechanisms were analyzed. Based on these findings, a theoretical formula for calculating the shear-bearing capacity of beams with repaired web reinforcement was proposed. Experimental results demonstrated that compared to single-component-modified epoxy resin, the optimally formulated composite adhesive improved the tensile strength, elongation at break, and bond strength by 4.07–21.16 MPa, 13.28–20.4%, and 1.05–3.79 MPa, respectively, while reducing the viscosity by 48–872 mPa·s. The viscosity of the adhesive was found to play a critical role in determining the repair effectiveness, with toughness enhancing the crack resistance and bond strength contributing to the structural stiffness recovery. The adhesive effectively penetrated the steel–concrete interface, forming a continuous bonding layer that improved energy dissipation and significantly enhanced the load-bearing capacity of the repaired beams. Full article

The output energy of Laser Active Optical Systems (LAOSs), in which image brightness is amplified within the laser-active medium, is always higher than the input energy. This contrasts with conventional optical systems (OSs). As a result, a LAOS enables the creation of laser beams with tailored energy distribution across the aperture, making them ideal for material processing applications. This concept was first successfully implemented using metal vapor lasers as the gain medium. In these systems, material processing was achieved by using a laser beam that either carried the required energy profile or the image of the object itself. Later, other laser media were utilized for LAOSs, including barium vapor, strontium vapor, excimer XeCl lasers, and solid-state media. Additionally, during the development of these systems, several modifications were introduced. For example, Space-Time Light Modulators (STLMs) and CCD cameras were incorporated, along with the use of multipass amplifiers, disk-shaped or thin-disk (TD) solid-state laser amplifiers, and other advancements. These techniques have significantly expanded the range of power, energy, pulse durations, and operating wavelengths. Currently, TD laser amplifiers and STLMs based on Digital Light Processor (DLP) technology or Digital Micromirror Devices (DMDs) enhance the potential to develop LAOS devices for Subtractive and Additive Technologies (ST, AT), applicable in both macromachining (cutting, welding, drilling) and micro-nano processing. This review presents comparable characteristics and requirements for these various LAOS applications. Full article

Flexure-based linear stages have become prevalent in precision engineering; however, most designs suffer from parasitic shifts that degrade positioning accuracy. Conventional solutions to mitigate these parasitic motions often compromise support stiffness, reduce motion range, and increase structural complexity. This study presents a novel family of flexure-based rectilinear-motion stages using coupled n-RRR planar parallel mechanisms, achieving extremely low parasitic shifts while addressing the forementioned limitations. Four design variants are selected and analyzed via Finite Element Method (FEM) simulations, evaluating parasitic shifts, stroke, and support stiffness. The most precise configuration, a 4-RRR rectilinear stage having kinematic chains coupled via two Watt linkages, exhibits a lateral shift smaller than 0.258 µm and an in-plane parasitic rotation smaller than 12.6 µrad over a 12 mm stroke. Experimental validation using a POM prototype confirms the high positioning precision and support stiffness properties. In addition, a silicon prototype incorporating thermally preloaded buckling beams is investigated to reduce its translational stiffness. Experimental results show a translational stiffness reduction of 98% in the monostable configuration and 112% in the bistable configuration (i.e., negative stiffness), without support stiffness reduction. These results highlight the potential of the proposed mechanisms for a wide range of precision applications, offering a scalable and high-accuracy solution for micro- and nano-positioning systems. Full article

Laser-generated structures have a huge potential to induce an alignment of biological cells, which may be important for various fields in medicine and biotechnology. We describe the formation of fs-laser-induced micro- and nanostructures for achieving the directed growth of Schwann cells, a type of glial cell that can support the regeneration of nerve pathways by guiding the neuronal axons in the direction of their alignment. Polymer surfaces, i.e., polycarbonate (PC) or cellulose acetate butyrate (CAB), were exposed to the beam of a 1040 nm Yb-based amplified fs-laser system with a pulse length of about 350 fs. With appropriate parameters, the laser exposure resulted in a surface topography with oriented micro-grooves, which, for PC, were covered with nano-ripples. Schwann cell growth on these substrates was inspected after 3 to 5 days of cultivation by means of scanning electron microscopy (SEM). We show that Schwann cells can grow in a certain direction, predetermined by micro-groove or nano-ripple orientation. In contrast, cells cultivated on randomly oriented nanofibers or unstructured surfaces show an omnidirectional growth behavior. This method may be used in the future to produce nerve conduits for the treatment of injuries to the peripheral nervous system. Full article

Micromotors play a crucial role in microsystems technology, with applications in nanoparticle propulsion, targeted drug delivery, and biosensing. Optical field propulsion, particularly optical tweezers (OTs), enables precise, noncontact control but traditionally relies on Gaussian traps, which require preprogramming and offer limited rotational control. Here, we introduce a micromotor driven by optical vortex beams, utilizing phase gradients to generate optical torque. This eliminates preprogramming and enables real-time control over rotation and positioning. Using this method, we design red blood cell (RBC)-based micromotors for targeted cellular debris collection in liquid environments. Our findings provide a versatile strategy for micro-/nano-object manipulation with potential applications in biomedicine and precision transport. Full article

Advanced packaging represents a crucial technological evolution aimed at overcoming limitations posed by Moore’s Law, driving the semiconductor industry from two-dimensional toward three-dimensional integrated structures. The increasing complexity and miniaturization of electronic devices have significantly heightened the challenges associated with failure analysis during process development. The focused ion beam–scanning electron microscope (FIB-SEM), characterized by its high processing precision and exceptional imaging resolution, has emerged as a powerful solution for the fabrication, defect localization, and failure analysis of micro- and nano-scale devices. This paper systematically reviews the innovative applications of FIB-SEM in the research of core issues, such as through-silicon-via (TSV) defects, bond interfacial failures, and redistribution layer (RDL) electromigration. Additionally, the paper discusses multimodal integration strategies combining FIB-SEM with advanced analytical techniques, such as high-resolution three-dimensional X-ray microscopy (XRM), electron backscatter diffraction (EBSD), and spectroscopy. Finally, it provides a perspective on the emerging applications and potential of frontier technologies, such as femtosecond-laser-assisted FIB, in the field of advanced packaging analysis. Full article

Light-actuated microbots have been studied as a viable tool for interacting with micro/nano environments. Considering their applicability to a wide range of biomedical applications, novel designs, fabrication techniques, and control methodologies are being developed. Especially, micro/nanoscale three-dimensional fabrication techniques have opened many possibilities for developing microbots with complex geometries using resins as materials. Here, we developed microbots that can be actuated with tightly focused laser beams to be used in targeted drug delivery, cell poking, and cell characterization studies. These microbots were fabricated in batches using two-photon polymerization (TPP). Each microbot utilizes a deposited metal layer inside its body to manipulate convective microfluidic flows. Additionally, micro-sized end effectors allow them to make measurable physical contact with biological objects. Their expected performance was evaluated using numerical simulations with the use of multiphysics software. Furthermore, laser-induced loading and unloading of micro-sized cargo show their capability for in vitro applications. Full article

Circularly polarized lasers can directly generate circularly polarized light without requiring complex external optics, enabling applications in biosensing, environmentally friendly antibacterial treatments, and cancer cell phototherapy. However, the circular dichroism (CD) of chiral metasurface mirrors—a core component of such lasers—typically remains below 3%, limiting beam quality. Using COMSOL simulations, we broke the metasurface’s structural symmetry via displacement and rotation operations, introducing chirality to the unit cell. At 980 nm, the metasurface achieved 99.85% reflectivity and 52% CD. Multipole analysis suggests this enhancement stems from electric dipole and quadrupole coupling. Our laser design could generate micro-nano-scale chiral light, advancing applications in biophotonics, biomedicine, and life sciences. Full article

This research explores the dynamic characteristics of composite nano-beams with a hybrid cellular structure (HCS) core, composed of two segments with distinct unit cell configurations, and face sheets reinforced with carbon nanotube (CNT) composites. By considering three-layered sandwich beams with aluminum cores of varying unit cell angles, the study explores a broad spectrum of achievable Poisson’s ratios. The top and bottom face sheets incorporate CNTs, distributed either uniformly or in a functionally graded manner. The governing equations are derived using Eringen’s nonlocal elasticity framework and the modified theory of shear deformation, with solutions obtained via the Galerkin method. A detailed parametric analysis is conducted to evaluate the effects of CNT content, arrangement configurations, hybrid core cellular angles, nonlocal parameters, and slenderness ratio (L/h) on the dimensionless natural frequencies of sandwich nanobeams with hybrid cellular cores. A key contribution of this study is the presentation of natural frequencies for nanobeams with hybrid cellular cores and composite face sheets reinforced with functionally graded CNTs, derived from advanced theoretical formulations. These findings offer new insights into design optimization and highlight the potential applications of hybrid cellular sandwich nanobeams in cutting-edge engineering systems. Full article

Focused Ion Beam (FIB) has been used to create single α-β colony micro-pillars from a polycrystalline commercial Ti-6Al-4V (Ti-64) sample. Each pillar was selected to have either a single alpha phase, a single beta phase, or two α lamella separated by a thin β phase filet. Then, utilizing a diamond flat tip as a compression platen, uniaxial micro-compression tests were performed on the single crystal α and β pillars as well as a tri-crystal α/β/α pillar using a nano-indenter. Then, utilizing a diamond flat tip as a compression platen, uniaxial micro-compression tests were performed on the single crystal alpha and beta pillars as well as a tri-crystal α/β/α pillar using a nano-indenter. Through the use of Electron Back Scattering Diffraction (EBSD) to choose the crystal orientation along the micro-pillar, three distinct unique slip systems have been selectively triggered by maximizing the Schmid factor for each system. The potential to localize a single crystal volume that can be characterized after deformation is one benefit of the micro-compression approach over traditional mechanical testing. The sample strengths compare well with published data. The mechanical properties of the α-β colonies and the single α and β phases have been compared in order to elucidate the role of the α/β interfaces in determining the critical resolved shear stress. Full article

Magnesium-doped hydroxyapatite/chitosan composite coatings produced by the radio-frequency magnetron sputtering technique were exposed to 5 MeV electron beams of 8 and 30 Gy radiation doses in a linear electron accelerator. The surfaces of unirradiated layers are smooth, while the irradiated ones exhibit nano-structures with sizes that increase from 60 nm at a 8 Gy dose to 200 nm at a 30 Gy dose. Young’s modulus and the stiffness of the layers decrease from 58.9 GPa and 10 µN/nm to 5 GPa and 2.2 µN/nm, respectively, when the radiation doses are increased from 0 to 30 Gy. These data suggest the diminishing of the contribution of the chitosan to the elasticity of the magnesium-doped hydroxyapatite/chitosan composite layers after electron beam irradiation. The biological capabilities of the coatings were assessed before and after their immersion in RPMI-1640 cell culture medium for 7 and 14 days, respectively, and further cultured with a MG63 cell line (ATCC CRL1427) in Dulbecco’s Modified Eagle Medium supplemented with fetal bovine serum, penicillin–streptomycin, and L-glutamine. Thus, 1 µm spherical structures were developed on the surfaces of the layers exposed to a 30 Gy radiation dose and immersed for 14 days in the RPMI-1640 biological medium. The molecular structures of all the RPMI-1640 immersed samples were modified by the growth of a carbonated hydroxyapatite layer characterized by a B-type substitution, as Fourier Transform Infrared Spectroscopy revealed. The biological assay proved the increased biocompatibility of the layers kept in RPMI-1640 medium and enhanced MG63 cell attachment and proliferation. Atomic force microscopy analysis indicated the elongated fibroblastic cell morphology of MG63 cells with minor alteration at 30 Gy irradiation doses as a result of layer biocompatibility modifications. Full article

The conventional method of cutting quartz glass with a knife often leads to undesirable effects, such as chipping, debris generation, and an inconsistent cut quality. Additionally, implementing the current methods of laser ablation cutting and crack control cutting presents challenges in ensuring both the quality of the cut and the efficiency of the process. Previous reports have documented a single direct cut of thin quartz glass, albeit at a thickness of only 200 μm. In this study, we utilized a pulse-width-tunable Gaussian beam, in combination with an axicon and a beam-reducing mirror, to generate a high-quality Bessel beam. This process endows the quartz glass with a nano-porous structure with a thickness of 1 mm, enabling high-quality cutting in a single pass. The effects of laser-cutting speed and pulse width on the cutting cross-section and cut surface were investigated. The results of the experiments show that using the optimal cutting speed and pulse width significantly improved cutting quality, reduced surface damage and sputtering, enabled the penetration of the modified cutting cross-section throughout the material, and decreased cutting cross-section roughness to 607 nm Ra. This technique holds promise for the laser-processing industry, enhancing both the quality and efficiency of cutting 1 mm thick quartz glass. Full article