Research

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14 pages, 3460 KiB

Open AccessArticle

Cinnamate-Intercalated Layered Yttrium Hydroxide: UV Light-Responsive Switchable Material

by Maria A. Teplonogova, Alexey D. Yapryntsev, Alexander E. Baranchikov and Vladimir K. Ivanov

Micromachines 2023, 14(9), 1791; https://doi.org/10.3390/mi14091791 - 19 Sep 2023

Viewed by 1066

In recent years, there has been an increasing interest in stimuli-responsive host–guest materials due to the high potential for their application in switchable devices. Light is the most convenient stimulus for operating these materials; a light-responsive guest affects the host structure and the [...] Read more.

In recent years, there has been an increasing interest in stimuli-responsive host–guest materials due to the high potential for their application in switchable devices. Light is the most convenient stimulus for operating these materials; a light-responsive guest affects the host structure and the functional characteristics of the entire material. UV-transparent layered rare earth hydroxides intercalated with UV-switchable anions are promising candidates as stimuli-responsive host–guest materials. The interlayer distance in the layered rare earth hydroxides depends on the size of the intercalated anions, which could be changed in situ, e.g., via anion isomerisation. Nevertheless, for layered rare earth hydroxides, the possibility of such changes has not been reported yet. A good candidate anion that is capable of intercalating into the interlayer space is the cinnamate anion, which undergoes UV-assisted irreversible trans–cis isomerisation. In this work, both trans- and cis-cinnamate anions were intercalated in layered yttrium hydroxide (LYH). Upon UV-irradiation, the interlayer distance of trans-cinnamate-intercalated layered yttrium hydroxide suspended in isopropanol changed from 21.9 to 20.6 Å. For the first time, the results obtained demonstrate the possibility of using layered rare earth hydroxides as stimuli-responsive materials. Full article

(This article belongs to the Special Issue Advanced Nanomaterials and Applied Nanotechnologies: Devices, Processes and Systems)

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15 pages, 9031 KiB

Open AccessArticle

Zirconia-Toughened Alumina (ZTA) Nanoceramics with a Gradient Microstructure: A Comparative Study of ZTA Ceramics with Fibrous and Granular Morphology

by Eszter Bódis and Zoltán Károly

Micromachines 2023, 14(9), 1681; https://doi.org/10.3390/mi14091681 - 28 Aug 2023

Viewed by 835

Abstract

ZrO₂-toughened Al₂O₃ (ZTA) ceramic composites with a porosity gradient and with improved mechanical properties have a wide range of possible applications. We fabricated nanofibrous and nanogranular Y-ZTA and Ce-ZTA composites with a gradient microstructure by creating a temperature [...] Read more.

ZrO₂-toughened Al₂O₃ (ZTA) ceramic composites with a porosity gradient and with improved mechanical properties have a wide range of possible applications. We fabricated nanofibrous and nanogranular Y-ZTA and Ce-ZTA composites with a gradient microstructure by creating a temperature gradient during SPS sintering, with the use of asymmetric graphite tool arrangement (ASY). In this study, we examined the morphology effect of the starting materials on the sintering process and on the final microstructure, as well as the mechanical properties of the composites. A large temperature difference was established for both the granular and fibrous samples fabricated in the ASY configuration, which resulted in gradient porosity along the ceramics bodies: the upper part of the ceramics showed a highly porous fine microstructure, while the opposite side was highly densified. The final microstructure of the composites can be tailored by varying the morphology of the starting ceramics or the graphite configuration. A highly porous skeleton-like structure was formed by sintering fibres in the ASY configuration, whereas the granular precursors resulted in a much less porous composite. The microstructure affected the mechanical properties of the composite. Improved hardness and more than 50% higher compression strength were obtained for the granular Ce-ZTA samples as compared to the fibrous sample. Gradient porosity with fibrous or granular morphology promotes the penetration of bioactive nanosized hydroxyapatite (HAp) into the pore structure. Fibrous ZTA absorbs HAp more effectively due to its higher porosity as well as its bimodal pore structure. Full article

(This article belongs to the Special Issue Advanced Nanomaterials and Applied Nanotechnologies: Devices, Processes and Systems)

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13 pages, 5193 KiB

Open AccessArticle

A Free-Standing Chitosan Membrane Prepared by the Vibration-Assisted Solvent Casting Method

by Urte Cigane, Arvydas Palevicius and Giedrius Janusas

Micromachines 2023, 14(7), 1419; https://doi.org/10.3390/mi14071419 - 14 Jul 2023

Viewed by 812

Abstract

Much attention has been paid to the surface modification of artificial skin barriers for the treatment of skin tissue damage. Chitosan is one of the natural materials that could be characterized by its biocompatibility. A number of methods for the preparation of chitosan [...] Read more.

Much attention has been paid to the surface modification of artificial skin barriers for the treatment of skin tissue damage. Chitosan is one of the natural materials that could be characterized by its biocompatibility. A number of methods for the preparation of chitosan membranes have been described in scientific articles, including solvent casting methods. This study investigates an improved technology to produce chitosan membranes. Thus, chitosan membranes were prepared using a vibration-assisted solvent casting method. First, aqueous acetic acid was used to pretreat chitosan. Then, free-standing chitosan membranes were prepared by solvent casting on nanoporous anodized aluminum oxide (AAO) membrane templates, allowing for the solvent to evaporate. Using finite element methods, a study was obtained showing the influence of chitosan solutions of different concentrations on the fluid flow into nanopores using high-frequency excitation. The height of the nanopillars and the surface area of the chitosan membrane were also evaluated. In this study, the surface area of the chitosan membrane was found to increase by 15, 10 and 6 times compared to the original flat surface area. The newly produced nanopillared chitosan membranes will be applicable in the fabrication of skin barriers due to the longer nanopillars on their surface and the larger surface area. Full article

(This article belongs to the Special Issue Advanced Nanomaterials and Applied Nanotechnologies: Devices, Processes and Systems)

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14 pages, 2644 KiB

Open AccessArticle

Investigation of Physico-Chemical Stability and Aerodynamic Properties of Novel “Nano-in-Micro” Structured Dry Powder Inhaler System

by Petra Party and Rita Ambrus

Micromachines 2023, 14(7), 1348; https://doi.org/10.3390/mi14071348 - 30 Jun 2023

Cited by 1 | Viewed by 1178

Abstract

Pulmonary drug transport has numerous benefits. Large surface areas for absorption and limited drug degradation of the gastrointestinal system are provided through the respiratory tract. The administration is painless and easy for the patient. Due to their better stability when compared to liquid [...] Read more.

Pulmonary drug transport has numerous benefits. Large surface areas for absorption and limited drug degradation of the gastrointestinal system are provided through the respiratory tract. The administration is painless and easy for the patient. Due to their better stability when compared to liquid formulations, powders have gained popularity among pulmonary formulations. In the pharmaceutical sector, quality assurance and product stability have drawn a lot of attention. Due to this, it was decided to perform a long-term stability study on a previously developed, nanosized dry powder inhaler (DPI) formulation that contained meloxicam. Wet milling was implemented to reduce the particle size, and nano spray-drying was used to produce the extra-fine inhalable particles. The particle diameter was determined using dynamic light scattering and laser diffraction. Scanning electron microscopy was utilized to describe the morphology. X-ray powder diffraction and differential scanning calorimetry were applied to determine the crystallinity. In an artificial lung medium, the in vitro dissolution was studied. The Andersen Cascade Impactor was used to investigate the in vitro aerodynamic characteristics. The stability test results demonstrated that the DPI formulation maintained its essential qualities after 6 and 12 months of storage. Consequently, the product might be promising for further studies and development. Full article

(This article belongs to the Special Issue Advanced Nanomaterials and Applied Nanotechnologies: Devices, Processes and Systems)

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13 pages, 3797 KiB

Open AccessArticle

A Novel Scheme for Full Bottom Dielectric Isolation in Stacked Si Nanosheet Gate-All-Around Transistors

by Jingwen Yang, Ziqiang Huang, Dawei Wang, Tao Liu, Xin Sun, Lewen Qian, Zhecheng Pan, Saisheng Xu, Chen Wang, Chunlei Wu, Min Xu and David Wei Zhang

Micromachines 2023, 14(6), 1107; https://doi.org/10.3390/mi14061107 - 24 May 2023

Cited by 1 | Viewed by 1719

Abstract

In this paper, a novel scheme for source/drain-first (S/D-first) full bottom dielectric isolation (BDI), i.e., Full BDI_Last, with integration of a sacrificial Si_0.5Ge_0.5 layer was proposed and demonstrated in a stacked Si nanosheet gate-all-around (NS-GAA) device structure using TCAD simulations. [...] Read more.

In this paper, a novel scheme for source/drain-first (S/D-first) full bottom dielectric isolation (BDI), i.e., Full BDI_Last, with integration of a sacrificial Si_0.5Ge_0.5 layer was proposed and demonstrated in a stacked Si nanosheet gate-all-around (NS-GAA) device structure using TCAD simulations. The proposed full BDI scheme flow is compatible with the main process flow of NS-GAA transistor fabrication and provides a large window for process fluctuations, such as the thickness of the S/D recess. It is an ingenious solution to insert the dielectric material under the source, drain and gate regions to remove the parasitic channel. Moreover, because the S/D-first scheme decreases the problem of high-quality S/D epitaxy, the innovative fabrication scheme introduces full BDI formation after S/D epitaxy to mitigate the difficulty of providing stress engineering in the full BDI formation before S/D epitaxy (Full BDI_First). The electrical performance of Full BDI_Last is demonstrated by a 4.78-fold increase in the drive current compared to Full BDI_First. Furthermore, compared to traditional punch through stoppers (PTSs), the proposed Full BDI_Last technology could potentially provide an improved short channel behavior and good immunity against parasitic gate capacitance in NS-GAA devices. For the assessed inverter ring oscillator (RO), applying the Full BDI_Last scheme allows the operating speed to be increased by 15.2% and 6.2% at the same power, or alternatively enables an 18.9% and 6.8% lower power consumption at the same speed compared with the PTS and Full BDI_First schemes, respectively. The observations confirm that the novel Full BDI_Last scheme incorporated into an NS-GAA device can be utilized to enable superior characteristics to benefit the performance of integrated circuits. Full article

(This article belongs to the Special Issue Advanced Nanomaterials and Applied Nanotechnologies: Devices, Processes and Systems)

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21 pages, 3595 KiB

Open AccessArticle

Nonlocal Strain Gradient Model for the Nonlinear Static Analysis of a Circular/Annular Nanoplate

by Mostafa Sadeghian, Arvydas Palevicius and Giedrius Janusas

Micromachines 2023, 14(5), 1052; https://doi.org/10.3390/mi14051052 - 15 May 2023

Cited by 2 | Viewed by 1293

Abstract

A nonlinear static analysis of a circular/annular nanoplate on the Winkler–Pasternak elastic foundation based on the nonlocal strain gradient theory is presented in the paper. The governing equations of the graphene plate are derived using first-order shear deformation theory (FSDT) and higher-order shear [...] Read more.

A nonlinear static analysis of a circular/annular nanoplate on the Winkler–Pasternak elastic foundation based on the nonlocal strain gradient theory is presented in the paper. The governing equations of the graphene plate are derived using first-order shear deformation theory (FSDT) and higher-order shear deformation theory (HSDT) with nonlinear von Karman strains. The article analyses a bilayer circular/annular nanoplate on the Winkler–Pasternak elastic foundation. HSDT while providing a suitable distribution of shear stress along the thickness of the FSDT plate, eliminating the defects of the FSDT and providing good accuracy without using a shear correction factor. To solve the governing equations of the present study, the differential quadratic method (DQM) has been used. Moreover, to validate numerical solutions, the results were compared with the results from other papers. Finally, the effect of the nonlocal coefficient, strain gradient parameter, geometric dimensions, boundary conditions, and foundation elasticity on maximum non-dimensional deflection are investigated. In addition, the deflection results obtained by HSDT have been compared with the results of FSDT, and the importance of using higher-order models has been investigated. From the results, it can be observed that both strain gradient and nonlocal parameters have significant effects on reducing or increasing the dimensionless maximum deflection of the nanoplate. In addition, it is observed that by increasing load values, the importance of considering both strain gradient and nonlocal coefficients in the bending analysis of nanoplates is highlighted. Furthermore, replacing a bilayer nanoplate (considering van der Waals forces between layers) with a single-layer nanoplate (which has the same equivalent thickness as the bilayer nanoplate) is not possible when attempting to obtain exact deflection results, especially when reducing the stiffness of elastic foundations (or in higher bending loads). In addition, the single-layer nanoplate underestimates the deflection results compared to the bilayer nanoplate. Because performing the experiment at the nanoscale is difficult and molecular dynamics simulation is also time-consuming, the potential application of the present study can be expected for the analysis, design, and development of nanoscale devices, such as circular gate transistors, etc. Full article

(This article belongs to the Special Issue Advanced Nanomaterials and Applied Nanotechnologies: Devices, Processes and Systems)

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10 pages, 3446 KiB

Open AccessArticle

Dynamic Mechanical Properties of PVC Plastics in the Formation of Microstructures with Novel Magnetostrictor

by Justas Ciganas, Algimantas Bubulis, Vytautas Jurenas, Paulius Griskevicius, Arvydas Palevicius, Sigita Urbaite and Giedrius Janusas

Micromachines 2023, 14(4), 820; https://doi.org/10.3390/mi14040820 - 06 Apr 2023

Viewed by 1017

Abstract

Molding in thermoplastic polymers using ultrasonic hot embossing technology is promising due to its high precision reproducibility. To understand, analyze and apply the formation of polymer microstructures by the ultrasonic hot embossing method, it is necessary to understand dynamic loading conditions. The Standard [...] Read more.

Molding in thermoplastic polymers using ultrasonic hot embossing technology is promising due to its high precision reproducibility. To understand, analyze and apply the formation of polymer microstructures by the ultrasonic hot embossing method, it is necessary to understand dynamic loading conditions. The Standard Linear Solid model (SLS) is a method that allows analyzing the viscoelastic properties of materials by representing them as a combination of springs and dashpots. However, this model is general, and it is challenging to represent a viscoelastic material with multiple relaxations. Therefore, this article aims to use the data obtained from dynamic mechanical analysis for extrapolation in a wide range of cyclic deformations and to use the obtained data in microstructure formation simulations. The formation was replicated using a novel magnetostrictor design that sets a specific temperature and vibration frequency. The changes were analyzed on a diffractometer. After the diffraction efficiency measurement, it was found that the highest quality structures were formed at a temperature of 68 °C, a frequency of 10 kHz, a frequency amplitude of 1.5 µm and a force of 1 kN force. Moreover, the structures could be molded on any thickness of plastic. Full article

(This article belongs to the Special Issue Advanced Nanomaterials and Applied Nanotechnologies: Devices, Processes and Systems)

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10 pages, 3247 KiB

Open AccessArticle

Impact of Stress and Dimension on Nanosheet Deformation during Channel Release of Gate-All-Around Device

by Jingwen Yang, Kun Chen, Dawei Wang, Tao Liu, Xin Sun, Qiang Wang, Ziqiang Huang, Zhecheng Pan, Saisheng Xu, Chen Wang, Chunlei Wu, Min Xu and David Wei Zhang

Micromachines 2023, 14(3), 611; https://doi.org/10.3390/mi14030611 - 07 Mar 2023

Cited by 1 | Viewed by 2122

Abstract

In this paper, nanosheet deformation during channel release has been investigated and discussed in Gate-All-Around (GAA) transistors. Structures with different source/drain size and stacked Si nanosheet lengths were designed and fabricated. The experiment of channel release showed that the stress caused serious deformation [...] Read more.

In this paper, nanosheet deformation during channel release has been investigated and discussed in Gate-All-Around (GAA) transistors. Structures with different source/drain size and stacked Si nanosheet lengths were designed and fabricated. The experiment of channel release showed that the stress caused serious deformation to suspended nanosheets. With the guidance of the experiment result, based on simulation studies using the COMSOL Multiphysics and Sentaurus tools, it is confirmed that the stress applied on the channel from source/drain plays an important role in nanosheet deformation during the fabrication process. The deformation of Si nanosheets would cause a serious degradation of the device performance due to an inability to control the work function of the metal gate. This study proposed that the uniformly stacked GAA nanosheets structure could be successfully demonstrated with suitable channel stress engineering provided by fitting S/D size and an appropriate channel length. The conclusions provide useful guidelines for future stacked GAA transistors’ design and fabrication. Full article

(This article belongs to the Special Issue Advanced Nanomaterials and Applied Nanotechnologies: Devices, Processes and Systems)

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13 pages, 3830 KiB

Open AccessArticle

Organic Light-Emitting Diodes with Electrospun Electrodes for Double-Side Emissions

by Iulia Corina Ciobotaru, Monica Enculescu, Silviu Polosan, Ionut Enculescu and Constantin Claudiu Ciobotaru

Micromachines 2023, 14(3), 543; https://doi.org/10.3390/mi14030543 - 25 Feb 2023

Cited by 4 | Viewed by 1328

Abstract

Transparent conductive electrodes (TCE) obtained by the electrospinning method and gold covered were used as cathodes in the organic light-emitting diodes (OLEDs) to create double side-emission. The electro-active nanofibers of poly(methyl methacrylate) (PMMA) with diameters in the range of several hundreds of nanometers, [...] Read more.

Transparent conductive electrodes (TCE) obtained by the electrospinning method and gold covered were used as cathodes in the organic light-emitting diodes (OLEDs) to create double side-emission. The electro-active nanofibers of poly(methyl methacrylate) (PMMA) with diameters in the range of several hundreds of nanometers, were prepared through the electrospinning method. The nanofibers were coated with gold by sputtering deposition, maintaining optimal transparency and conductivity to increase the electroluminescence on both electrodes. Optical, structural, and electrical measurements of the as-prepared transparent electrodes have shown good transparency and higher electrical conductivity. In this study, two types of OLEDs consisting of indium tin oxide (ITO)/ poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT-PSS)/ Ir(III) complex (8-hydroxyquinolinat bis(2-phenylpyridyl) iridium–IrQ(ppy)₂ 20 wt% embedded in N, N′-Dicarbazolyl-4,4′-biphenyl (CBP) sandwich structure and either gold-covered PMMA electrospun nanoweb (OLED with electrospun cathode) were fabricated together with a similar structure containing thin film gold cathodes (OLED with thin film cathode). The luminance-current-voltage characteristics, the capacitance-voltage, and the electroluminescence properties of these OLEDs were investigated. Full article

(This article belongs to the Special Issue Advanced Nanomaterials and Applied Nanotechnologies: Devices, Processes and Systems)

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14 pages, 4347 KiB

Open AccessArticle

The Armor of the Chinese Sturgeon: A Study of the Microstructure and Mechanical Properties of the Ventral Bony Plates

by Yu Zheng, Xin Li, Ping Liu, Ying Chen and Ce Guo

Micromachines 2023, 14(2), 256; https://doi.org/10.3390/mi14020256 - 19 Jan 2023

Cited by 1 | Viewed by 1312

Abstract

Benefiting from their unique morphological characteristics and structural properties, the ventral bony plates of the Chinese sturgeon are excellent biological protective tissue. In this work, we studied the micro- and macro-morphology and mechanical properties of the ventral bony plates of the Chinese sturgeon [...] Read more.

Benefiting from their unique morphological characteristics and structural properties, the ventral bony plates of the Chinese sturgeon are excellent biological protective tissue. In this work, we studied the micro- and macro-morphology and mechanical properties of the ventral bony plates of the Chinese sturgeon to elucidate the special protective mechanisms of the bony plates. Experiments involving scanning electron microscopy and energy-dispersive X-ray spectroscopy revealed that the bony plates possess a hierarchical structure and a ridge-like shape. This structure comprises a surface layer containing mineralized nanocrystals and an internal layer containing mineralized collagen fibers. From the surface layer to the internal layer, the degree of mineralization decreases gradually. Nanoindentation, tension, and compression tests demonstrated that the bony plates feature excellent mechanical properties and a high specific tensile strength comparable to that of stainless steel. Moreover, water can significantly improve the fracture toughness and deformability of the bony plates and effectively enhance the damage tolerance of the structures. The obtained results concerning the microstructure–property–function relationships of the ventral bony plates of the Chinese sturgeon may provide novel insights for designing protective structures that are both lightweight and high strength. Full article

(This article belongs to the Special Issue Advanced Nanomaterials and Applied Nanotechnologies: Devices, Processes and Systems)

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Review

Jump to: Research

21 pages, 9457 KiB

Open AccessReview

Transition-Metal Dichalcogenides in Electrochemical Batteries and Solar Cells

by Mohammad Bagher Askari, Parisa Salarizadeh, Payam Veisi, Elham Samiei, Homa Saeidfirozeh, Mohammad Taghi Tourchi Moghadam and Antonio Di Bartolomeo

Micromachines 2023, 14(3), 691; https://doi.org/10.3390/mi14030691 - 21 Mar 2023

Cited by 10 | Viewed by 2697

Abstract

The advent of new nanomaterials has resulted in dramatic developments in the field of energy production and storage. Due to their unique structure and properties, transition metal dichalcogenides (TMDs) are the most promising from the list of materials recently introduced in the field. [...] Read more.

The advent of new nanomaterials has resulted in dramatic developments in the field of energy production and storage. Due to their unique structure and properties, transition metal dichalcogenides (TMDs) are the most promising from the list of materials recently introduced in the field. The amazing progress in the use TMDs for energy storage and production inspired us to review the recent research on TMD-based catalysts and electrode materials. In this report, we examine TMDs in a variety of electrochemical batteries and solar cells with special focus on MoS₂ as the most studied and used TMD material. Full article

(This article belongs to the Special Issue Advanced Nanomaterials and Applied Nanotechnologies: Devices, Processes and Systems)

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