Nano Features Research Articles

A qualitative validation of an in-situ monitoring system for EHD inkjet printing via laser diffraction

Electrohydrodynamic inkjet printing enables high-resolution patterning for nano features. In-flight dynamics of EHD inkjet printing play an essential role in the quality control of printing results. We applied a laser diffraction/scattering in-situ analyzing setup for the EHD inkjet printing system to replace the zoom lens and high-speed camera imaging system. In contrast to conventional imaging systems, the laser diffraction/scattering system is based on analyzing the diffraction pattern and scattering intensity, respectively, which provided higher resolution for micro-scale jetting measurement and enabled sub-micron level jetting correlation between the voltage applied to the electrode and printing results. Furthermore, Taylor cone information from the nozzle head could also be analyzed in real-time to make adjustments to the printing process. In this work, we successfully validated the feasibility of laser diffraction analysis in-situ monitoring for EHD inkjet printing at micron and sub-micron levels.

Hydrophobic Coatings with Charge Permeability via Plasma Deposition of Long-Chain Perfluorocarbons.

Hydrophobization of nanotextured catalyst materials is a promising route to enhance the yield of N2 and CO2 conversion into green fuels. However, these applications require a hydrophobic coating to not only promote air trapping but also allow charge transfer at the electrode-electrolyte interface. In this work, nano thin films with thicknesses as low as 7 nm were deposited from the plasma phase of perfluorohexene, perfluorodecene, and perfluorooctane (PFO) precursors using a mild vacuum and gentle powers. Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) characterization reveal that the resulting films are conformal and hydrophobic thanks to a good retention of CF2 and CF3 moieties. The PFO films exhibited the highest water contact angle and achieved superhydrophobic states when deposited on top of re-entrant nano features, an indication of successful air trapping. Electrochemical studies further demonstrated that the plasma-deposited PFO films allow charge transfer but could only sustain repeated cyclic voltammetry cycles without losing their hydrophobicity when deposited under optimal conditions. This result indicates that plasma deposition could become a viable route for the hydrophobization of electrocatalysts required to enhance the yield of poorly soluble gas reduction reactions.

Optimizing ammonium vanadate crystal structure by facile in situ phase transformation of VO2/NH4V4O10 with special micro–nano feature for advanced aqueous zinc ion batteries

NH4+-defected NH4V4O10 with microflower morphology was synthesized via hydrothermal method and in situ phase transition to improve specific capacity (494.0 mA h g−1), Zn2+ diffusion efficiency and structural stability (71.8% for 2000 cycles).

Disruption of diatom attachment on marine bioinspired antifouling materials based on Brill (Scophthalmus rhombus)

Bioinspired surfaces, due to their nano and micro topographical features, offer a promising approach for the development of novel antifouling solutions. The study of surface topography has gained popularity in recent years, demonstrating significant potential in mimicking natural structures that could be manufactured for application in the marine environment. This research focuses on investigating the antifouling (AF) performance of bio-inspired micro-textures inspired by Brill fish scales, Scophthalmus rhombus, under static laboratory conditions, using two common fouling diatom species, Amphora coffeaeformis and Nitzschia ovalis. In this study, we evaluate six engineered surfaces, inspired by Brill fish scales, fabricated through a 2-photon polymerization (2PP) process, for their potential as antifouling solutions. The investigation explores the settlement behaviour of microfouling organisms, comparing these mechanisms with theoretical models to guide the future design of antifouling materials. A key emphasis is placed on the impact of surface topography on the disruption of cellular response. Our results suggest that cells smaller than 10 μm, exceeding the peak-to-peak distances between surface features, comfortably position themselves between adjacent features. On the other hand, as peak-to-peak distances decrease, cells shift from settling within uniform gaps to resting on top of surface features. Surfaces with sharpened edges demonstrate a more substantial reduction in diatom attachments compared to those with rounded edges. Furthermore, all micro-textured surfaces exhibit a significant decrease in colony formation compared to control samples. In conclusion, this study shows the potential to manipulate cellular responses through topographical features, providing valuable insights for the design of effective antifouling materials. The results contribute to the growing body of knowledge in biomimetic antifouling strategies using a novel marine organism for inspiration to design practical structures that can be replicated.

Water repellence of biomimetic structures fabricated via femtosecond laser direct writing

Femtosecond laser direct writing based on two-photon polymerization (TPP), which is a sub-classification of vat photopolymerization, has the advantages of unlimited geometrical freedom and high resolution, and has attracted significant interests from scientists and engineers in recent years. In the present study, TPP fabrication was performed using a laser equipment with wavelength of 514 nm. The collimated beam diameter before the focusing lens was measured as 5 mm and the focused laser spot diameter was calculated as 280 nm. Key TPP processing parameters were investigated for the fabrication of nanowires, and micro/ nanoscale biomimetic structures, including cone and pinecone structures. The finest nanowire has a diameter of 105 nm and is achieved at the laser power of 0.8 μW (near the laser polymerization threshold). For the three-dimensional (3D) structures, laser power, layer thickness and hatch spacing would influence the fabrication accuracy. Generation of a stiff 3D cone structure would require a minimum laser power of 1.4 μW when the hatch spacing and layer thickness are 200 nm. The optimum processing parameters (laser power 2.2 μW, hatch space and layer thickness 100 nm) can generate structures with dimensions close to the design values. For pinecones with nano features, the scanning strategies play a significant role in the nano fabrication accuracy. A row of pinecones and cones were fabricated and tested for their water repellence performance. The relationship between the performance and the nano cone density was investigated. The pinecone structures exhibit superior performance to the ones with no nano-scale structures, indicating that improved hydrophobicity can be achieved by designing the micro/nano hierarchical structures. The increased number density of the nano cones in a micro/nano hierarchical structure was found to profoundly enhance the water repellence of the structures. The mechanisms were discussed with Wenzel and Cassie models.

Geomorphometry and microelectronic metrology: Converged realms

AbstractThis article discusses the application of geomorphometric methods in microelectronic metrology. Six typical microelectronic items were geomorphometrically analyzed using their digital elevation models with nano‐ and micrometer‐range resolution and elevation difference: (1) a silicon–quartz structure; (2) a mechanically polished silicon wafer; (3) a photovoltaic blend sample; (4) an X‐ray optical element (a fused quartz spherical concave substrate); (5) a Bosch process‐formed, 20 aluminum layered membrane; and (6) a silicon–glass assembly with a volumetric defect. Geomorphometric modeling increases significantly the visibility and informativeness of data presentation, allowing to identify effectively the spatial distribution of nano‐ and microforms of the surface of microelectronic items. Geomorphometric methods provide an opportunity to study the size, location, and characteristic features of nano‐ and microtopographic inhomogeneities of microelectronic items using maps of minimum, maximum, mean, and unsphericity curvatures as well as other morphometric variables.

A Coupled 3d Morphological Reconstruction Approach for Surface Microcrack in Si3 n4 Ceramic Bearing Roller Based on Adaptive Nano Feature Extraction & Multiscale Depth Fusion.

To extract the fuzzy contour features, tiny depth features of surface microcracks in the Si3 N4 ceramic bearings roller. An adaptive nano feature extraction and multiscale deep fusion coupling method is proposed, to sufficiently reconstruct the three-dimensional morphology characteristics of surface microcracks. Construct an adaptive nano feature extraction method, form the surface microcrack image scale space and the Gaussian difference pyramid function equation, realize the detection and matching of global feature points. The sparse point cloud is obtained. Through polar-line correction, depth estimation, and fusion of feature points on the surface microcracks image, a multiscale depth fusion matching cost pixel function is established to realize a dense point cloud reconstruction of surface microcracks. The reconstruction results show that the highest value of the local convex surface reconstructed by the dense point cloud reaches 1183nm, and the lowest local concave surface is accurate to 296nm. Compared with the measurement results of the confocal platform, the relative error of the reconstruction result is 24.6%. The overall feature-matching rate of the reconstruction reaches 93.3%. It provides a theoretical basis for the study of surface microcrack propagation mechanism and the prediction of bearing life.

Nanotextured porous titanium scaffolds by argon ion irradiation: Toward conformal nanopatterning and improved implant osseointegration.

Stress shielding and osseointegration are two main challenges in bone regeneration, which have been targeted successfully by chemical and physical surface modification methods. Direct irradiation synthesis (DIS) is an energetic ion irradiation method that generates self-organized nanopatterns conformal to the surface of materials with complex geometries (e.g., pores on a material surface). This work exposes porous titanium samples to energetic argon ions generating nanopatterning between and inside pores. The unique porous architected titanium (Ti) structure is achieved by mixing Ti powder with given amounts of spacer NaCl particles (vol % equal to 30%, 40%, 50%, 60%, and 70%), compacted and sintered, and combined with DIS to generate a porous Ti with bone-like mechanical properties and hierarchical topography to enhance Ti osseointegration. The porosity percentages range between 25% and 30% using 30 vol % NaCl space-holder (SH) volume percentages to porosity rates of 63%-68% with SH volume of 70 vol % NaCl. Stable and reproducible nanopatterning on the flat surface between pores, inside pits, and along the internal pore walls are achieved, for the first time on any porous biomaterial. Nanoscale features were observed in the form of nanowalls and nanopeaks of lengths between 100 and 500 nm, thicknesses of 35-nm and heights between 100 and 200 nm on average. Bulk mechanical properties that mimic bone-like structures were observed along with increased wettability (by reducing contact values). Nano features were cell biocompatible and enhanced in vitro pre-osteoblast differentiation and mineralization. Higher alkaline phosphatase levels and increased calcium deposits were observed on irradiated 50 vol % NaCl samples at 7 and 14 days. After 24 h, nanopatterned porous samples decreased the number of attached macrophages and the formation of foreign body giant cells, confirming nanoscale tunability of M1-M2 immuno-activation with enhanced osseointegration.

Chitosan-based nerve guidance conduit with microchannels and nanofibers promotes schwann cells migration and neurite growth

Peripheral nerve injury (PNI) is the leading cause of permanent dysfunction in movement and sensation. Despite the rapid development of tissue engineering in peripheral nerve regeneration, autograft remains the gold standard for treating PNI. Synthesized nerve guidance conduits (NGCs) were reported as a potential alternative treatment that could replace autograft. However, most current NGCs are hollow tubular structured, or NGCs with macro or microstructures, but not both. These simple structures could not meet the need for neurite and Schwann cell guidance and accelerate peripheral nerve regeneration. In the current study, we combine unidirectional freezing with electrospinning to produce a unique NGC with longitudinal microchannels and parallel nanofibers. The in vitro study showed the importance of having both features in promoting Schwann cell growth, migration, and PC-12 cells neurite elongation. The novel NGCs could provide desirable physical support and guidance for peripheral nerve regeneration. From the current study, we found both the micro feature and the nano feature are helpful in terms of helping cell migrating through the NGCs, and the combination of both features will have a syngeneic effect.

Cost-effective Programmable Logic Arrays Using Multilayer Structures of Decoders in QCA Framework

The emerging nanotechnology paradigm, Quantum Dot Cellular Automata (QCA) in particular, is gaining a wide recognition due to its high speed, nano feature size and considerably low power consumption. The QCA architecture not only provide potential alternative for Complementary Metal Oxide Semiconductor (CMOS) circuits but its multilayer topology facilitates an added benefit of cost efficacy and immunity towards random interference. Moreover, design of programmable logic devices in QCA is vital to promote the multi-utility and resiliency of the computing circuits. This paper presents the multilayer designs of 2×4 and 3×8 decoder circuits in QCA framework with 55.1% and 51.17% better cost efficiency respectively, over the earlier reported designs. The presented 3×8 decoder circuit is further utilized to implement Programmable Logic Array (PLA) to realize Boolean functions of adder and subtractor. The presented circuits are cost effective and showcase the significance of programmable devices in nano-computing.

Sustainable Solar Light Photodegradation of Diclofenac by Nano- and Micro-Sized SrTiO3

Currently, photocatalytic reactions under solar illumination have attracted worldwide attention due to the tremendous set of associated environmental problems. Taking sunlight into account, it is indispensable to develop highly effective photocatalysts. Strontium titanate, SrTiO3 (STO), is a cubic perovskite-type semiconductor, an inexpensive material with high thermal stability and corrosion resistance that exhibits a similar energy bandgap to TiO2 and can represent an interesting alternative in photocatalytic applications. Particle size can significantly affect both photocatalytic and photoelectrochemical properties of a photocatalyst, thus altering the photooxidation of organic pollutants in air or water. In this context, this research aims at investigating the photocatalytic features of nano- and micro-sized commercial STO powders towards the photodegradation of diclofenac (DFC), a non-steroidal, anti-inflammatory drug, widely used as analgesic, antiarthritic, and antirheumatic. Both nano- and micro-STO photocatalysts exhibited remarkable photocatalytic efficiency towards DCF, reaching photodegradation efficiency higher than 90% within one hour. Results obtained in simulated drinking water were also compared to those obtained in ultrapure water. Both STOs showed good stability during recycling tests, maintaining high performances after three cycles. Eventually, active species were identified using various scavengers by trapping holes and radicals generated during the photocatalytic degradation process.

Influence of Nano-additive on the Performance of Diesel with Rape Seed Oil as Bio-diesel

Increased consumption of oil in a spectrum of uses currently poses a significant risk to worldwide level of exhaust emissions. Considering this problem requires considerable thought. As a result, the development of alternate fuels has become necessary. Bio-diesel is a renewable fuel made from mono - alkyl esters. This laboratory investigation contains a comparison analysis to ascertain the impact and operational features of nano fuel additives. The study focused on the mixing of rape seed oil based bio-diesel with silicon dioxide (SiO2), a nanoparticle based enhancer, in order to determine its influence on diesel burning IC engine's performance. Various nano-mixture proportions were produced using nano-SiO2 particles with bio-diesel. The fuel used in the tests was bio-diesel mixer containing 25% of rape seed oil in diesel with 0.1%, 0.2%, and 0.3% SiO2 nanoparticles in bio-diesel. The output metrics such as brake power and exhaust emission levels were determined for the tested bio-diesels with different nano-SiO2 proportions. The bio-diesel with the 0.2% SiO2 nanoparticles yielded the better result in terms of brake power and emission characteristics of the engine comparing to the other blends.

A structural study of the self-association of different starches in presence of bacterial cellulose fibrils

A multi-analytical study was performed to analyse the effect of bacterial cellulose (BCF) on the self-association of starches with different amylose content (wheat, waxy-maize), assessing macrostructural properties (rheology, gel strength) and some nano and sub-nano level features (small and wide-angle X-ray scattering). Although pasting viscosities and G′ were significantly increased by BCF in both starches, cellulose did not seem to promote the self-association of amylose in short-range retrogradation. A less elastic structure was reflected by a 2–3-fold increase in loss factor (G″/G′) at the highest BCF concentration tested. This behavior agreed with the nano and sub-nano characterisation of the samples, which showed loss of starch lamellarity and incomplete full recovery of an ordered structure after storage at 4 °C for 24 h. The gel strength data could be explained by the contribution of BCF to the mechanical response of the sample. The information gained in this work is relevant for tuning the structure of tailored starch-cellulose composites.

Effect of plant extracts on structural & morphological features of CuO nano structured material

Cupper oxide (CuO) nano structured material has been synthesized by using eco-friendly simple solution method using plant leaf extracts(Mangifera indica, Carica papaya and Azadirachta indica) as a reducing agent. The obtained material is subjected to calcination at 500 °C for further studies. Powder X-ray diffraction (PXRD) and Fourier transmittance Infrared spectroscopy (FTIR) was performed for the structural confirmation of the calcined CuO samples.The CuO prepared by using Mangifera indica, Carica papaya and Azadirachta indica leaf extracts exhibited flake shape, irregular and spherical structures respectively in scanning electron microscope (SEM) micrographs.In addition, the UV-Visible absorption spectrum was recorded and the energy gap determined by using Tauc relation was 3.5, 3.75 and 3.9eV for Mangifera indica, Carica papaya and Azadirachta indica respectively.

Effect of particle-size distribution and pressure-induced densification on the microstructure and properties of printable thermoelectric composites and high energy density flexible devices

To address the global demand for low-cost, flexible thermoelectric generators (TEGs), this work describes a novel, energy-efficient method of controlling the composite microstructure and resulting thermoelectric (TE) properties of p-type composite films. Combining (1) a small amount of naturally occurring binder that is sufficient to hold TE particles together without significantly decreasing electrical conductivity and (2) a wide distribution of heterogeneous (micro and nano) particles tightly packed on (3) application of mechanical pressure at (4) low-temperature curing for a short duration, this method yields big grains larger than the mean free path for charge carriers (for high electrical conductivity) and nano features smaller than the mean free path for phonons (for low thermal conductivity). The best properties were achieved with 0.05 wt% of chitosan binder, heterogeneous-sized TE particles (100-mesh Bi0.5Sb1.5Te3), 200 MPa applied uniaxial pressure, and curing at 150 °C for 30 min to densify the as-deposited films. The 100-mesh chitosan-BST composite film achieved a ZT of 0.7, comparable to the best reported ZT of printed p-type TE films, but without using high-temperature and long-duration curing. The power output of our best-reported scalable 3-leg-BST TEG was 58 μW. The corresponding power density was 5.72 mW/cm2 at a temperature difference of 38 K, significantly higher than the best reported values for single-leg TEGs. Furthermore, the flexibility of this prototype was performed by successfully bending at a 3-cm radius for 1000 cycles, thus demonstrating a high potential to be used as self-sufficient batteries for next-generation wearable devices and wireless sensor network applications.

A preliminary study on polycaprolactone and gelatin-based bilayered tubular scaffolds with hierarchical pore size constructed from nano and microfibers for vascular tissue engineering

Due to the insufficient endothelialization and the poor colonization of smooth muscle cells (SMCs), small-diameter vascular tissue engineering is still challenging. An ideal vascular graft is expected to effectively support the formation of endothelial monolayer and the colonization of SMCs. In this study, we proposed a bilayered scaffold with hierarchical pore size constructed from nano and microfibers by electrospinning PCL-PEG-PCL (PCE) and a blend of PCE and gelatin (PCEG) sequentially. The structural features of nano and microfibers were tuned by the concentration of PCE and the proportion of PCE/gelatin in electrospun solution respectively. The results demonstrated the best nanofiber morphology and relatively high mechanical properties were achieved in 18% PCE (w/v) (PCE18) and PCE and gelatin with a weight ratio of 7:3 (P7G3) at a concentration of 18% (w/v) electrospun membranes. The in vitro co-culturing studies of cells and membranes indicated all the PCE membranes supported the proliferation and spreading of endothelial cells and the further endothelialization of the membranous surface, while PCEG membranes facilitated the migration inward of SMCs. Taking the porosity and mechanical properties into consideration, PCE18 and P7G3 were chosen to construct the inner and outer layers of the bilayered scaffold with hierarchical pore size respectively. The circumferential ring test demonstrated that the bilayered scaffold has good mechanical property both in dry and wet state. After cells were co-cultured with this bilayered scaffold for 7 days, the results manifested a continuous endothelial monolayer has formed on the luminal surface and the SMCs have started to colonized from outer layers, indicating the vast potential of this bilayered scaffold in vascular remodeling and regeneration.

Preparation of Amyloid Fibrils Using Recombinant Technology.

Amyloid fibrils are widely investigated as they are directly associated with various neurodegenerative diseases. For example, a vast of experimental results have shown that the oligomeric and fibrillar aggregates of the amyloid β-peptide (Aβ) play a critical role in the pathogenesis of Alzheimer's disease (AD). Therefore, the accessibility of certain amounts of pure Aβ peptide is necessary for the studies of the mechanism of neurotoxicity. In this regard, recombinant methods provide the possibility to synthesize the Aβ peptide in vitro and thus promote the investigation of the relationship between peptide structure and pathogenic mechanism. These investigations further provide the fundamental supports for developing potential drugs for AD treatment. In addition to providing support for the study of pathogenic mechanisms, the recombination of Aβ peptides also offers the possibility to utilize these unique protein nanomaterials. For example, Aβ peptides tend to assemble into chiral amyloid fibrils with an ultra-high aspect ratio. These unique nano features, together with the inherent protein characteristics, of amyloid fibrils, allow them to be used in biomedical and environmental fields. Accordingly, herein, we aim to introduce the recombinant protocols for the synthesis of Aβ peptides. The experimental route to assemble these peptides to amyloid fibrils is also summarized in this chapter.

Експериментальна система для дослідження впливу компонування заповнювачів негерметичних відсіків на густину потоків газовиділення

In recent years, components and materials of industrial and commercial quality have been in frequent use in the assembly of small spacecraft to reduce the cost of space projects. This may affect spacecraft and onboard equipment reliability and performance quality. In particular, a high risk may arise from unpredictable performance characteristics of components and materials of this type caused by outgassing flows of unregulated density. The situation is aggravated by difficulties in numerical simulation of the complex internal geometry of actual nonhermetic small spacecraft. The most efficient way to resolve this problem is to conduct laboratory tests. This paper presents an experimental system for studying the dependence of degassing processes on the geometry of arrangement of electronics boards and various structural materials in a nonhermetic module. The theoretic basis for experiments is a differential realization of the accumulation method, which allows one to differentiate the density of degassing flows from particularly arranged specimens and elements of the module’s inner surface. To reproduce the design features of nonhermetic nano- and picosatellites, models of nonhermetic modules were refined, and a special laboratory module was made on their basis. For this purpose, a unit of synchronous module evacuation control was updated, equipment was developed for positioning plate-type fillers of nonhermetic modules, the recording of gas-dynamic parameters of a nonhermetic module’s own internal atmosphere was provided, and an automated experiment control system was prepared. The laboratory module was integrated into the automated measuring system of the VAU-2M vacuum aerodynamic installation of the Institute of Technical Mechanics of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine. The experimental system developed was tested to show a satisfactory operability of both its components and the system as a whole. The system developed allows one to study outgassing from the surface of various components and materials, to measure the density of outgassing flows for various equipment arrangements, and to study the dynamics of outflow of the products of the own internal atmosphere through calibrated orifices, which simulate the outflow of the own internal atmosphere of a nonhermetic module through its unregulated clearances.

Directing Surface Functions by Inducing Ordered and Irregular Morphologies at Single and Two‐Tiered Length Scales

Surface topography outlines material's interaction with its immediate environment. Herein, a series of cost‐effective and scalable treatments are used to obtain single‐scale and two‐tiered surfaces with ordered/disordered arrangements of micro and nano features. The applied treatments induced a wide variety of surface features regarding length scale and arrangement. The individual and synergistic contributions of roughness length scale, regularity, and hierarchy are analyzed on surface functionalities. The performance of further functionalized and lubricant‐infused surfaces is evaluated regarding their interaction with wetting media, as well as tribological and electrochemical resistance. The hierarchical surfaces show improved wear and corrosion resistance. The prominence of the surface features’ length scale and orderedness varies based on the loading conditions and test environments. Wettability is mainly directed by micro‐scale features. Tribology is largely led by the ability of the surfaces in forming a stable low‐surface‐energy liquid interface. Electrochemical activity is primarily influenced by the synergic barrier effect of the nano‐features and the infused lubricant regardless of their arrangement. The results indicate that combining the distinctive and complementary role of micro and nano features can offer the possibility of obtaining versatile multifunctional surfaces with tunable performances based on the expected in‐service conditions.

Effect of initial wetting state on plastron recovery through heating

Applicability of superhydrophobic surfaces depends on maintaining the trapped gas pockets in the micro/nano roughness valleys of the surface. It is well known that besides efforts of scientists to construct robust surfaces against wetting transition, it is also desirable to develop strategies to restore the lost plastron underwater. The current paper systematically investigates the effect of initial wetting state on the possibility of plastron recovery. It is shown that different temperature for water and surface as well as different air solubility in water can result in different wetting state. It is also shown that despite the Cassie–Baxter state which skips nucleate boiling and leads to film boiling, in Wenzel state, heating results in nucleate boiling and nucleate bubbles easily detach from the surface due to strong contact line pinning. Interestingly, when surface has parahydrophobic behavior (water wets the micro structures but the nano features remain dry), the plastron is revivable through existing air in the water; but if we degas the water the plastron can be recovered by applying heat flux.