Search Results (42)

Flow sensing is essential in biomedical engineering, industrial process control, and environmental monitoring. Conventional sensors, while accurate, are often constrained by high fabrication costs, complex processes, and limited design flexibility, restricting their use in disposable or rapidly customizable applications. This paper presents a novel ultra-low-cost airflow sensor fabricated entirely through fused deposition modeling 3D printing. The device employs a cantilever-based structure printed with PETg filament, followed by the deposition of a conductive ABS piezoresistive layer in a two-step process requiring no curing or post-processing. Experimental characterization reveals that the sensor operates in an ultra-low pressure range of 0.88–26.68 Pa, corresponding to flow velocities of 1.2–6.6 m/s. The sensor achieves a sensitivity of 967 Ω/Pa, a resolution of 9.27 Pa, and a detection limit of 83.27 Pa, with a total resistance change of approximately 51.5 kΩ. This kilo-ohm-scale response enables direct readout via a digital multimeter without requiring Wheatstone bridges or instrumentation amplifiers. The minimalist design, combined with sub-5 min fabrication time and material cost below $0.05, positions this sensor as an accessible platform for disposable, scalable, and resource-constrained flow monitoring applications in both biomedical and industrial contexts. Full article

Superhydrophobic coatings on aluminum play a crucial role in enhancing corrosion resistance in harsh marine and chloride-rich environments. This study introduces a scalable fabrication method for superhydrophobic aluminum surfaces exhibiting outstanding corrosion resistance. The process involves a two-step technique combining chemical etching with atmospheric pressure chemical vapor deposition (AP-CVD) of perfluorooctyltriethoxysilane (PFOTES). Hierarchical micro- and nanostructures were created by HCl etching, followed by conformal PFOTES functionalization to impart low surface energy. The fabricated surfaces demonstrated water contact angles reaching as high as 175°, coupled with very-low-contact-angle hysteresis, indicative of the Cassie–Baxter wetting state. Electrochemical analyses in saline environments demonstrated a substantial increase in charge transfer resistance and a reduction in corrosion rates by more than an order of magnitude compared to uncoated aluminum, with inhibition efficiencies exceeding 98%. Extended salt spray testing corroborated the durability and efficacy of the dual-modified surfaces. This facile and cost-effective method offers promising prospects for multifunctional aluminum components in marine, infrastructure, and aerospace applications where long-term protection against aggressive environments is required. Full article

High-quality AZO thin films were produced on a 4-inch Si substrate using large-area PLD equipment at a substrate temperature of 330 °C, with a ZnO: Al (98:2 wt.%) target. This study aims to enhance the electrical, optical, morphological and structural properties of large-area PLD-grown AZO thin films by tuning the deposition pressures. The samples were prepared under high-vacuum (HV) conditions, as well as in oxygen atmospheres of 0.005 mbar O₂, 0.01 mbar O₂, and 0.1 mbar O₂. Consequently, a bilayer AZO film was prepared in a combination of two deposition pressures (first layer prepared under HV, followed by the second layer prepared at 0.01 mbar O₂). Additionally, morphological and structural characterization revealed that high-quality columnar growth AZO thin films free of droplets, with a strong (002) orientation, were achieved on a 4-inch Si substrate. Moreover, Hall measurements in the Van der Pauw configuration were used to assess the electrical properties. A low electrical resistivity of 3.98 × 10⁻⁴ Ω cm, combined with a high carrier concentration (n) of 1.05 × 10²¹ cm⁻³ and a charge carrier mobility of 17.9 cm²/V s, was achieved at room temperature for the sample prepared under HV conditions. The optical characterization conducted through spectroscopic ellipsometry measurements showed that the large-area AZO sample exhibits an increased optical transparency in the visible (VIS) range with a near-zero extinction coefficient (k) and a wide bandgap of 3.75 eV, fulfilling the standards for materials classified as TCO. In addition, the increased thickness uniformity of the prepared AZO films over a large area represents a significant step in scaling the PLD technique for industrial applications. Full article

Vanadium pentoxide (V₂O₅) has attracted considerable interest owing to its unique chemical and physical properties. However, traditional synthesis methods are often time-consuming, complex, and difficult to scale, limiting the broader applications of V₂O₅. Herein, we present a flame vapor deposition (FVD) method to enable rapid, scalable, and one-step synthesis of various V₂O₅ nanostructures under ambient pressure conditions. By optimizing critical synthesis parameters, specifically, source temperature (840 °C) and substrate temperature (610 °C), we achieved highly crystalline, one-dimensional (1D) V₂O₅ nanorods on a variety of substrates, including silicon (Si), fluorine tin doped (FTO) glass, stainless steel, and silicon dioxide (SiO₂). Moreover, we demonstrate the rapid growth of ultrathin, two-dimensional (2D) V₂O₅ nanoflakes with nanometer-scale thickness, as well as enhanced uniformity and coverage density with an externally applied electric field. This FVD method provides a simple, efficient, and scalable approach for synthesizing advanced V₂O₅ nanostructures, significantly expanding opportunities for their integration into various technological applications. Full article

The key equipment for performing aerodynamic testing of objects, such as road and railway vehicles, aircraft, and wind turbines, as well as stationary objects such as bridges and buildings, are multichannel pressure measurement instruments (pressure scanners). These instruments are typically based on arrays of separate pressure sensors built in an enclosure that also contains temperature sensors used for temperature compensation. However, there are significant limitations to such a construction, especially when increasing requirements in terms of miniaturization, the number of pressure channels, and high measurement performance must be met at the same time. In this paper, we present the development and realization of an innovative MEMS multisensor chip, which is designed with the intention of overcoming these limitations. The chip has four MEMS piezoresistive pressure-sensing elements and two resistive temperature-sensing elements, which are all monolithically integrated, enabling better sensor matching and thermal coupling while providing a high number of pressure channels per unit area. The main steps of chip development are preliminary chip design, numerical simulations of the chip’s mechanical behavior when exposed to the measured pressure, final chip design, fabrication processes (photolithography, thermal oxidation, diffusion, layer deposition, micromachining, anodic bonding, and wafer dicing), and electrical testing. Full article

Ionized metal physical vapor deposition (IMPVD), which is operated at a very low pressure to take advantage of the metal sputtering effect on the target surface, has unique properties compared with conventional DC magnetron sputtering. In this study, we investigated the effect of the rotating magnetic field on the plasma formation of IMPVD to enhance the deposition uniformity. This was accomplished through a multi-step simulation, which enabled plasma analysis, sputtered particle and chemical reaction analysis, and deposition profile analysis. A two-dimensional particle-in-cell Monte Carlo simulation utilizes the exact cross-section data of the Cu ion collisions and calculates the particle trajectories under specific magnetic field profiles. This new methodology gives guidance for the design of the magnetic field profiles of IMPVD and an understanding of the physical mechanism. Full article

Tunnel oxide passivating contact cells have become the mainstream form of high-performance photovoltaic cells; however, the key factor restricting the further improvement of tunnel oxide passivating contact cell performance lies in the deposition process technology of high-quality polysilicon films. The experimental optimization cost for the deposition of large-sized polysilicon films in low-pressure chemical vapor deposition reactors is enormous when conducted in the temperature range of 800–950 K; hence, the necessity to develop effective computer simulation models becomes urgent. In recent years, our research group has conducted two-dimensional simulation research on large-sized, low-pressure chemical vapor deposition. This article focuses on analyzing the influence of gas-phase chemical reactions on the contribution rate of polysilicon film deposition under a mixed atmosphere of H₂ and SiH₄. The findings indicate that when using SiH₄ as the precursor reactants with a gas pressure not exceeding 100 Pa, SiH₄ contributes more than 99.6% to the deposition of polysilicon films, while the contribution rate of intermediates from chemical reactions to film deposition is less than 0.5% with 860–900 K. The influence of temperature on the contribution rate of gas-phase intermediates is negligible. It is found that simulating complex multi-step chemical reactions is highly resource-intensive, making it difficult to achieve the three-dimensional simulations of large-sized tubular LPCVD reactors. Based on the in-depth analysis of the mechanism and simulation results, a simplified model neglecting the complex multi-step chemical reaction process has been proposed. Through employing this refined and simplified model, the two-dimensional simulation of the polysilicon thin films deposition process in the large-sized tubular low pressure chemical vapor deposition reactor will become more effective and resource efficient. Full article

In this paper, we explore a straightforward two-step method to produce high-purity, vertically aligned multi-walled carbon nanofibres (MWCNFs) via chemical vapor deposition (CVD). Two distinct solutions are utilized for this CVD method: a catalytic solution consisting of ferrocene and acetonitrile (ACN) and a carbon source solution with camphor and ACN. The vapors of the catalytic solution inserted in the reaction chamber through external boiling result in a floating catalyst CVD approach that produces vertically aligned CNFs in a consistent manner. CNFs are grown in a conventional CVD horizontal reactor at 850 °C under atmospheric pressure and characterized by Raman spectroscopy, scanning and transmission electron microscopy (SEM and TEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Coating the MWCNTs with polymethyl methacrylate (PMMA) while still on the Si substrate retains the structure and results in a flexible, conductive thin film suitable for flexible electrodes. The film is 62 μm thick and stable in aqueous solutions, capable of withstanding further processing, such as electropolymerization with polyaniline, to be used for energy storage applications. Full article

The development of pressure ulcers, associated with increased temperature and moisture in specific areas of the body, and the risk of microbial infections in patients lying in a static position for prolonged periods of time represents a serious issue in medicine. In order to prevent the formation of pressure ulcers, this work aims to present advanced nanostructured coatings developed by three research groups. Nanometric silver, ash and functionalized torrefied biomass were the basis for the treatment of wound dressings to improve thermal conductivity and antimicrobial properties of the conventional cotton gauzes. Each treatment was performed according to its own optimized method. The treated fabrics were characterized in terms of antimicrobial properties, heat transfer, morphology and hydrophobic behavior. The results demonstrated the effectiveness of the deposition treatments also in synergistic actions. In particular, the antibacterial efficacy was improved in all the samples by the addition of silver treatment, and the thermal conductivity was enhanced by around 58% with nanometric ashes. A further step of the study involved the designing of two multilayer systems evaluated using circuit models for determining the total thermal conductivity. In this way, both systems were designed with the aim to guarantee simultaneous efficacy: high antibacterial and hydrophilic properties at the skin level and more hydrophobic and conductive behaviors toward the external environment. Full article

We report a two-step growth process of MoS₂ nanoflakes using a low-pressure chemical vapor deposition technique. In the first step, a MoS₂ layer was synthesized on a c-plane sapphire substrate. This layer was subsequently re-evaporated at a higher temperature to form mono- or few-layer MoS₂ flakes. As a result, the close proximity re-evaporation enabled the growth of pristine MoS₂ nanoflakes. Atomic force microscopy analysis confirmed the synthesis of nanoclusters/nanoflakes with lateral dimensions of over 10 μm and a flake height of approximately 1.3 nm, demonstrating bi-layer MoS₂, whereas transmission electron microscopy analysis revealed triangular MoS₂ nanoflakes, with a diffraction pattern proving the presence of single crystalline hexagonal MoS₂. Raman data revealed the typical modes of high-quality MoS₂ nanoflakes. Finally, we presented the photocurrent dependence of a MoS₂-based photoresist under illumination with light-emitting diode of 405 nm wavelength. The measured current–voltage dependence across various luminous flux outlined the sensitivity of MoS₂ to polarized light and thus opens further opportunities for applications in high-performance photodetectors with polarization sensitivity. Full article

Tourmaline, a boron-bearing mineral, has been extensively applied as a geothermometer, provenance indicator, and fluid-composition recorder in geological studies. In this paper, the decomposition capability of an HF-HNO₃–mannitol mixture for a tourmaline sample was investigated in detail for the first time, and a wet acid digestion method based on the boron–mannitol complex for accurate boron determination in tourmaline by inductively coupled plasma mass spectrometry (ICP-MS) was proposed. With a digestion temperature of 140 °C, tourmaline samples of 25 mg (±0.5 mg) can be completely decomposed by a ternary mixture, which consisted of 0.6 mL of HF, 0.6 mL of HNO₃, and 0.7 mL of 2% mannitol (wt.), via a continuous heating treatment of 36 h. Following gentle evaporation at 100 °C, the sample residues were re-dissolved using 2 mL of 40% HNO₃ solution (wt.) and diluted to about 2.0 × 10⁵-fold by a two-step method using 2% HNO₃ solution (wt.). The boron contents in a batch of parallel tourmaline samples were then determined by ICP-MS, and results showed that the boron concentration levels were in a range of 3.20–3.44% with determination RSDs less than 4.0% (n = 5). It was found that the boron concentrations obtained at the mass of ¹⁰B were comparable with results from the measurements at the mass of ¹¹B. This revealed that the usage of 2% mannitol with a quantity as high as 0.7 mL in this developed approach did not exhibit significant effect on the quantification accuracy of boron at the mass of ¹¹B. It was also found that the processes including fluoride-forming prevention and fluoride decomposition deteriorated the boron-reserving efficiency of mannitol for tourmaline, causing the averaged boron contents to vary from 2.25% to 3.57% (n = 5). Furthermore, the stability of the boron–mannitol complex under 185 °C by applying the laboratory high pressure-closed digestion method was evaluated, which showed that there existed a 60.36% loss of boron compared to that under 140 °C by using this proposed approach. For this ternary mixture, the tourmaline decomposing efficiency was found to be weakened prominently using 100 °C as the digestion temperature, and tourmaline powders can be observed even after 72 h of continuous heating with B contents within 1.09–1.23% (n = 5). To assess the accuracy of this developed method, the boron recovery of anhydrous lithium tetraborate was studied. It was found that the boron recoveries were within 96.59–102.12% (RSD < 1%, n = 5), demonstrating the accuracy and reliability of this proposed method, which exhibits advantages of high B preserving efficiency, and giving concentration information of both B and trace elements simultaneously. By applying such a boron–mannitol complex-based wet acid digestion method, the chemical composition of boron and trace elements in three tourmaline samples from different pegmatites were quantified, which provided valuable information to distinguish regional deposits and the associated evolution stages. Full article

We chose to study the bottom structure stress evolution law in the process of undercut area advancement via the block caving method, reveal the influence law of the undercut rate on the effect of the ore body caving process, and assess the floor stress evolution law in the process of the undercut area with a different undercut rate in order to guide the production of a natural disintegration method under horizontal ground stress and also provide some reference value for rock damage assessment. According to the actual engineering and physical parameters of the mine, a numerical simulation model was created by using finite discrete element software GPI-3D-FDEM, and the Neo–Hookean hyperelastic constitutive model was adopted for calculation purposes. The simulation process follows a backward bottoming approach and monitors and analyses the stress state of the substructure after each bottoming step. The indoor physical model is employed to conduct similar two–dimensional simulation experiments on similar materials, investigating the motion laws of overlying rock layers. The research findings indicate that as bottom blasting progresses, a gradual concentration of compressive stress occurs in the foundation structure ahead of the advancing line. If this stress surpasses the rock mass’s shear failure limit, ground pressure failure may ensue. During mineral extraction from the bottom, internal stress within the fractured fault zone significantly diminishes compared to adjacent rock and ore deposits. Full article

We present a two-step physical method for the fabrication of composite nanoparticle-based nanostructures. The proposed method is based on the pulsed laser deposition (PLD) technique performed sequentially in vacuum and in air. As a first step, thin-alloyed films of iron with noble metal were deposited by PLD in vacuum. The films were prepared by ablation of a mosaic target formed by equal iron and gold sectors. As a second step, the as-prepared alloyed films were ablated in air at atmospheric pressure as the laser beam scanned their surface. Two sets of experiments were performed in the second step, namely, by applying nanosecond (ns) and picosecond (ps) laser pulses for ablation. The structure, microstructure, morphology, and optical properties of the samples obtained were studied with respect to the laser ablation regime applied. The implementation of the ablation process in open air resulted in the formation of nanoparticle and/or nanoparticle aggregates in the plasma plume regardless of the ablation regime applied. These nanoparticles and/or nanoaggregates deposited on the substrate formed a complex porous structure. It was found that ablating FeAu films in air by ns pulses resulted in the fabrication of alloyed nanoparticles, while ablation by ps laser pulses results in separation of the metals in the alloy and further oxidation of Fe. In the latter case, the as-deposited structures also contain core–shell type nanoparticles, with the shell consisting of Fe-oxide phase. The obtained structures, regardless of the ablation regime applied, demonstrate a red-shifted plasmon resonance with respect to the plasmon resonance of pure Au nanoparticles. Full article

It is usually difficult to realize high mobility together with a low threshold voltage and good stability for amorphous oxide thin-film transistors (TFTs). In addition, a low fabrication temperature is preferred in terms of enhancing compatibility with the back end of line of the device. In this study, α-IGZO TFTs were prepared by high-power impulse magnetron sputtering (HiPIMS) at room temperature. The channel was prepared under a two-step deposition pressure process to modulate its electrical properties. X-ray photoelectron spectra revealed that the front-channel has a lower Ga content and a higher oxygen vacancy concentration than the back-channel. This process has the advantage of balancing high mobility and a low threshold voltage of the TFT when compared with a conventional homogeneous channel. It also has a simpler fabrication process than that of a dual active layer comprising heterogeneous materials. The HiPIMS process has the advantage of being a low temperature process for oxide TFTs. Full article

Sodium hypochlorite (NaClO) is widely used for the chemical cleaning of fouled ultrafiltration (UF) membranes. Various studies performed on polymeric membranes demonstrate that long-term (>100 h) exposure to NaClO deteriorates the physicochemical properties of the membranes, leading to reduced performance and service life. However, the effect of NaClO cleaning on ceramic membranes, particularly the number of cleaning cycles they can undergo to alleviate irreversible fouling, remains poorly understood. Silicon carbide (SiC) membranes have garnered widespread attention for water and wastewater treatment, but their chemical stability in NaClO has not been studied. Low-pressure chemical vapor deposition (LP-CVD) provides a simple and economical route to prepare/modify ceramic membranes. As such, LP-CVD facilitates the preparation of SiC membranes: (a) in a single step; and (b) at much lower temperatures (700–900 °C) in comparison with sol-gel methods (ca. 2000 °C). In this work, SiC ultrafiltration (UF) membranes were prepared via LP-CVD at two different deposition temperatures and pressures. Subsequently, their chemical stability in NaClO was investigated over 200 h of aging. Afterward, the properties and performance of as-prepared SiC UF membranes were evaluated before and after aging to determine the optimal deposition conditions. Our results indicate that the SiC UF membrane prepared via LP-CVD at 860 °C and 100 mTorr exhibited excellent resistance to NaClO aging, while the membrane prepared at 750 °C and 600 mTorr significantly deteriorated. These findings not only highlight a novel preparation route for SiC membranes in a single step via LP-CVD, but also provide new insights about the careful selection of LP-CVD conditions for SiC membranes to ensure their long-term performance and robustness under harsh chemical cleaning conditions. Full article