Search Results (155)

During the last few years, the requirements for highly efficient, sustainable, and versatile materials in modern biomedicine, aircraft and aerospace industries, automotive production, and electronic and electrical engineering applications have increased. This has led to the development of new and innovative methods for material modification and optimization. This can be achieved in many different ways, but one such approach is the application of surface thin films. They can be conductive (metallic), semi-conductive (metal-ceramic), or isolating (polymeric). Special emphasis is placed on applying semi-conductive thin films due to their unique properties, be it electrical, chemical, mechanical, or other. The particular thin films of interest are composite ones of the type of transition metal oxide (TMO) and transition metal nitride (TMN), due to their widespread configurations and applications. Regardless of the countless number of studies regarding the application of such films in the aforementioned industrial fields, some further possible investigations are necessary to find optimal solutions for modern problems in this topic. One such problem is the possibility of characterization of the applied thin films, not via textbook approaches, but through a simple, modern solution using their electrical properties. This can be achieved on the basis of measuring the films’ electrical impedance, since all different semi-conductive materials have different impedance values. However, this is a huge practical work that necessitates the collection of a large pool of data and needs to be based on well-established methods for both characterization and formation of the films. A thorough review on the topic of applying thin films using physical vapor deposition techniques (PVD) in the field of different modern applications, and the current results of such investigations are presented. Furthermore, current research regarding the possible methods for applying such films, and the specifics behind them, need to be summarized. Due to this, in the present work, the specifics of applying thin films using PVD methods and their expected structure and properties were evaluated. Special emphasis was paid to the electrical impedance spectroscopy (EIS) method, which is typically used for the investigation and characterization of electrical systems. This method has increased in popularity over the last few years, and its applicability in the characterization of electrical systems that include thin films formed using PVD methods was proven many times over. However, a still lingering question is the applicability of this method for backwards engineering of thin films. Currently, the EIS method is used in combination with traditional techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), and others. There is, however, a potential to predict the structure and properties of thin films using purely a combination of EIS measurements and complex theoretical models. The current progress in the development of the EIS measurement method was described in the present work, and the trend is such that new theoretical models and new practical testing knowledge was obtained that help implement the method in the field of thin films characterization. Regardless of this progress, much more future work was found to be necessary, in particular, practical measurements (real data) of a large variety of films, in order to build the composition–structure–properties relationship. Full article

Multilayer thin films composed of cobalt (Co), carbon (C), and chromium (Cr) possess promising electromagnetic properties, yet the combined Co–C–Cr system remains underexplored, particularly regarding its performance as a microwave absorber. Existing research has primarily focused on binary Co–C or Co–Cr compositions, leaving a critical knowledge gap in understanding how ternary multilayer architectures influence electromagnetic behavior. This study addresses this gap by investigating the structure, phase composition, and microwave absorption performance of Co–C–Cr multilayer coatings fabricated via magnetron sputtering onto porous silicon substrates. This study compares four-layer and eight-layer configurations to assess how multilayer architecture affects impedance matching, reflection coefficients, and absorption characteristics within the 8.2–12.4 GHz frequency range. Structural analyses using X-ray diffraction and transmission electron microscopy confirm the coexistence of amorphous and nanocrystalline phases, which enhance absorption through dielectric and magnetic loss mechanisms. Both experimental and simulated results show that increasing the number of layers improves impedance gradients and broadens the operational bandwidth. The eight-layer coatings demonstrate a more uniform absorption response, while four-layer structures exhibit sharper resonant minima. These findings advance the understanding of ternary multilayer systems and contribute to the development of frequency-selective surfaces and broadband microwave shielding materials. Full article

The application of graphene nanoplatelets (GNPs) in polymer composites is a challenge due to their high tendency to agglomerate and restack during processing. In this work, alkyl phosphonium-based ionic liquid was used to assist the dispersion of GNP in an ethylene-vinyl acetate (EVA) matrix, through a melt-mixing procedure. The mechanical properties and creep resistance of the films prepared by the film extrusion process were evaluated. The results demonstrated that the noncovalent treatment of GNP with the ionic liquid (IL) enhanced the electrical conductivity and creep stability of the EVA composites. The microwave absorbing properties were studied in the X-band and Ku-band. A reflection loss (RL) of −15 dB for EVA containing 0.5 wt% of GNP and 1:1 wt% of GNP/IL was achieved. The use of a multi-layered structure containing thin film layers was efficient for enhancing the microwave absorbing performance, with a minimum RL of −24.6 dB and effective absorption bandwidth of 4.3 GHz. This result is attributed to the internal reflection and scattering of the radiation between layers. The use of simple, low-cost materials and procedures, combined with the system’s excellent mechanical and electrical properties, makes it a promising candidate for multifunctional applications as electrostatic dissipative and microwave absorbing materials for electronic packaging and other electronic devices. Full article

Aloe Vera (Aloe barbadensis Miller), a historically revered medicinal plant, has garnered great scientific attention due to its polysaccharide-rich bioactive compounds with significant therapeutic potential. This review examines the role of Aloe Vera polysaccharides as therapeutic agents in biomedical applications, highlighting their benefits as well as the risks. Traditionally recognized for its anti-inflammatory and antimicrobial effects, which are very important in wound healing, the Aloe Vera relies on its polysaccharides, which confer immunomodulatory, antioxidant, and tissue-regenerative properties. These compounds have shown promise in various applications, including skin repair, tissue engineering scaffolds, and antiviral therapies, with their delivery being facilitated via gels, thin films, or oral formulations. This review explores also their mechanisms of action and applications in modern medicine, including in the development of topical gels, dietary supplements, and innovative delivery systems such as thin films and scaffolds. Despite the promising benefits, the review addresses the possible side effects too, including allergic reactions, gastrointestinal disorders, and drug interactions, emphasizing the importance of understanding these risks for their safe clinical use. Assessing both the advantages and challenges of Aloe Vera polysaccharide medical use, this review contributes to the ongoing dialog regarding the integration of natural products into therapeutic practices, ultimately supporting informed decisions regarding their clinical application. Full article

The growing burden of degenerative, cardiovascular, neurodegenerative, and cancerous diseases necessitates innovative approaches to improve our pathophysiological understanding and ability to modulate biological processes. Organic bioelectronics has emerged as a powerful tool in this pursuit, offering a unique ability to interact with biology due to the mixed ionic–electronic conduction and tissue-mimetic mechanical properties of conducting polymers (CPs). These materials enable seamless integration with biological systems across different levels of complexity, from monolayers to complex 3D models, microfluidic chips, and even clinical applications. CPs can be processed into diverse formats, including thin films, hydrogels, 3D scaffolds, and electrospun fibers, allowing the fabrication of advanced bioelectronic devices such as multi-electrode arrays, transistors (EGOFETs, OECTs), ion pumps, and photoactuators. This review examines the integration of CP-based bioelectronics in vivo and in in vitro microphysiological systems, focusing on their ability to monitor key biological events, including electrical activity, metabolic changes, and biomarker concentrations, as well as their potential for electrical, mechanical, and chemical stimulation. We highlight the versatility and biocompatibility of CPs and their role in advancing personalized medicine and regenerative therapies and discuss future directions for organic bioelectronics to bridge the gap between biological systems and electronic technologies. Full article

Gallium nitride (GaN) is commonly used in various semiconductor systems owing to its high mobility and thermal stability; however, the production of GaN thin films using the currently employed methods requires improvement. To facilitate the growth of high-quality GaN epitaxial thin films, this study explored the crystallographic structures, properties, and influences of chromium nitride (CrN) buffer layers sputtered under various conditions. The crystallographic orientation of CrN played a crucial role in determining the GaN film quality. For example, even when the crystallinity of the CrN (111) plane was relatively low, a single-phase CrN (111) buffer layer could provide a more favorable template for GaN epitaxy compared to cases where both the CrN (111) and Cr₂N (110) phases coexisted. The significance of a low-temperature (LT) GaN nucleation layer deposited onto the CrN buffer layers was assessed using atomic force microscopy and contact angle measurements. The X-ray phi scan results confirmed the six-fold symmetry of the grown GaN, further emphasizing the contribution of an LT-GaN nucleation layer. These findings offer insights into the underlying mechanisms governing GaN thin film growth and provide guidance for the optimization of the buffer layer conditions to achieve high-quality GaN epitaxial films. Full article

BaTiO₃ (BTO), a lead-free chalcogenide ferroelectric material, has emerged as a promising candidate for ferroelectric memories due to its advantageous ferroelectric properties, notable flexibility, and mechanical stability, along with a high dielectric constant and minimal leakage. These attributes lay a crucial foundation for multi-value storage. In this study, high-quality BaTiO₃ ferroelectric thin films have been successfully prepared on STO substrates by pulsed laser deposition (PLD), and Pt/BaTiO₃/SrRuO₃/SrTiO₃ ferroelectric heterojunctions were finally prepared by a combination of UV lithography and magnetron sputtering. Characterization and performance tests were carried out by AFM, XRD, and a semiconductor analyzer. The results demonstrate that the ferroelectric heterojunction prepared in this study exhibits excellent ferroelectric properties. Furthermore, the device demonstrates fatigue-free operation after 10⁷ bipolar switching cycle tests, and the polarization value exhibits no significant decrease in the holding characteristic test at 10⁴ s, thereby further substantiating its exceptional reliability and durability. These findings underscore the considerable promise of BTO ferroelectric memories for nonvolatile storage applications and lay the foundation for the development in the fields of both in-memory computing systems and neuromorphic computing. Full article

Fungal infections pose a significant global health problem, affecting 20–25% of the population and contributing to over 3.75 million deaths annually. Clotrimazole (CLO) is a widely used topical antifungal drug, but its efficacy is limited by poor penetration through the stratum corneum. Microneedle (MN) systems, composed of micron-scale structures arranged on a patch, offer a promising strategy to overcome the outermost skin barrier and enhance drug penetration into deeper layers. However, optimizing MN design, particularly in terms of size, shape, and fabrication technology, is essential for efficient drug delivery. This study aimed to develop CLO-coated MN systems using an Liquid Crystal Display (LCD)-based 3D printing technique and a thin-film dip-coating method. A comprehensive optimization of printing parameters, including anti-aliasing, layer thickness, curing time, and printing angle, was conducted to ensure the desired mechanical properties. The optimized MNs were coated with either suspension or ethanol-based CLO-hydrogels, with ethanol hydrogel demonstrating superior characteristics. Additionally, the study investigated how microneedle geometry and coating formulation influenced drug release. Antifungal activity against reference and clinical origin Candida albicans strains varied significantly depending on the coating formulation. Finally, the acute toxicity test confirmed no significant toxic effects on Aliivibrio fischeri, indicating the potential biocompatibility and safety of the developed MN-based drug delivery system. Full article

Polyimide-based dielectric materials, as excellent high-temperature-resistant polymers, play a crucial role in advanced electronic devices and power systems. However, given the limitations of composite PI materials, it is a significant challenge to simultaneously improve the dielectric constant and breakdown strength of intrinsic polyimide dielectric materials to achieve high energy density. In this study, an indiscriminate copolymerization method was proposed, which utilizes two different diamine monomers with bulky side groups (-CF3) and high polarity (C-O-C), respectively, to copolymerize with the same dianhydride monomer and prepare a series of intrinsic PI films. Remarkably, PI films with a highly dipolar rigid backbone maintain excellent thermal and mechanical properties while enhancing dipole polarization. Meanwhile, a high breakdown strength of PI is shown, because the bulky side groups act as deep traps to capture and disperse charges during the charge transfer process. Under the optimal copolymer ratio, the dielectric constant and dielectric loss are 4.2 and 0.008, respectively. At room temperature, the highest breakdown strength reaches 493MV/m, and the energy storage density and charge–discharge efficiency are 5.07 J/cm³ and 82%, respectively. Finally, based on density functional theory calculations, the copolymerization tendencies of the three monomers are verified, and it is speculated that the copolymerization ratio of PI-60% is the most stable and exhibits the best overall performance, which perfectly aligns with the experimental results. These experimental results demonstrate the exciting potential of intrinsic polyimide in thin film capacitors. Full article

The integration of two-dimensional (2D) nanomaterials into polymer-based packaging presents a promising avenue for sustainable, high-performance materials. This perspective explores the roles of colloidal interactions in the assembly of 2D materials into thin films for packaging applications. We begin by analyzing the types of colloidal forces present in 2D nanomaterials and their impact on dispersion and stability. We then explore how these colloidal forces can be modulated through chemical structure, ionic intercalation, and shear forces, influencing the stacking behavior and orientation of 2D materials within the films. The incorporation of these 2D materials into polymer-based packaging systems is also considered, with a focus on how surface functionalization and dispersion techniques enhance their interaction with the polymer matrix to improve barrier properties against gases and moisture, increase mechanical strength, and impart antimicrobial effects. This work underscores the critical role of colloidal interactions in optimizing the design and performance of 2D-nanomaterial-based packaging for sustainable development. Full article

This review article’s primary aim is to discuss different thin-film deposition technique methods and their important uses. The histories of thin-film technology, thin-film growth, thin-film classification, and thin-film preparation techniques are also covered in this review article. The preparation and characterization of functional thin films and nanostructured materials, as well as various devices based on these materials and recent developments are also focused on in this review. The properties of the materials and several thin-film deposition techniques are also covered in this article. This review article also discusses the classification and application of thin-film sensors. Furthermore, the formation of thin films and their physical properties are impacted by deposition conditions such as pH, temperature, deposition time, and deposition parameters, which are analyzed. This article discusses how a wide range of potential uses in structural, mechanical, and protective coatings; sensing; energy storage systems; catalysis; optoelectronics; and biomedicine are made possible by the special qualities of thin films and nanostructured materials, including their high surface area to volume ratio, structure, surface charge, anisotropic nature, and tunable functionalities. Full article

Surface roughness significantly affects the performance of microelectromechanical systems (MEMS) and piezoelectric films. This study investigates the impact of surface roughness on the mechanical properties of thin piezoelectric films using nanoindentation and scanning probe microscopy (SPM). Four piezoelectric films with different thicknesses (220, 350, and 450 nm) and substrate configurations (LNO/SiO₂/Si or LNO/Si) were analyzed. A discriminant analysis revealed that the fractal dimension is more effective than the arithmetic mean height (Sa) for distinguishing surfaces, with only 2% misclassification versus 25% for Sa. A multiscale analysis identified the Smr2 parameter with low-pass filtering at 140 nm as highly effective for surface discrimination, achieving only 0.1% misclassification. The analysis of the roughness parameter Sa at various scales showed that band-pass filtering at 500 nm yielded a 0.7% misclassification rate, indicating its relevance for fractal roughness characterization. Most relevant roughness parameters for mechanical property correlation were found: Smr2 with low-pass filtering at 500 nm correlated best with hardness (R² = 0.82), and Vvc with low-pass filtering at 2 nm correlated best with reduced elastic modulus (R² = 0.84). These results demonstrate that surface roughness features like valley volume and voids significantly impact the apparent mechanical properties of piezoelectric films. Full article

We start presenting an overview on recent applications of linear polymers and networks in condensed matter physics, chemistry and biology by briefly discussing selected papers (published within 2022–2024) in some detail. They are organized into three main subsections: polymers in physics (further subdivided into simulations of coarse-grained models and structural properties of materials), chemistry (quantum mechanical calculations, environmental issues and rheological properties of viscoelastic composites) and biology (macromolecules, proteins and biomedical applications). The core of the work is devoted to a review of theoretical aspects of linear polymers, with emphasis on self-avoiding walk (SAW) chains, in regular lattices and in both deterministic and random fractal structures. Values of critical exponents describing the structure of SAWs in different environments are updated whenever available. The case of random fractal structures is modeled by percolation clusters at criticality, and the issue of multifractality, which is typical of these complex systems, is illustrated. Applications of these models are suggested, and references to known results in the literature are provided. A detailed discussion of the reptation method and its many interesting applications are provided. The problem of protein folding and protein evolution are also considered, and the key issues and open questions are highlighted. We include an experimental section on polymers which introduces the most relevant aspects of linear polymers relevant to this work. The last two sections are dedicated to applications, one in materials science, such as fractal features of plasma-treated polymeric materials surfaces and the growth of polymer thin films, and a second one in biology, by considering among others long linear polymers, such as DNA, confined within a finite domain. Full article

This paper presents the results of a study on the characteristics of semiconductor sensors based on thin SnO₂ films modified with antimony, dysprosium, and silver impurities and dispersed double Pt/Pd catalysts deposited on the surface to detect carbon monoxide (CO). An original technology was developed, and ceramic targets were made from powders of Sn-Sb-O, Sn–Sb-Dy–O, and Sn–Sb-Dy-Ag–O systems synthesized by the sol–gel method. Films of complex composition were obtained by RF magnetron sputtering of the corresponding targets, followed by technological annealing at various temperatures. The morphology of the films, the elemental and chemical composition, and the electrical and gas-sensitive properties were studied. Special attention was paid to the effect of the film composition on the stability of sensor parameters during long-term tests under the influence of CO. It was found that different combinations of concentrations of antimony, dysprosium, and silver had a significant effect on the size and distribution of nanocrystallites, the porosity, and the defects of films. The mechanisms of degradation under prolonged exposure to CO were examined. It was established that Pt/Pd/SnO₂:0.5 at.% Sb film with optimal crystallite sizes and reduced porosity provided increased stability of carbon monoxide sensor parameters, and the response to the action of 100 ppm carbon monoxide was G₁/G₀ = 2–2.5. Full article

In this paper, the previously proposed shaft-loaded blister test technique for the synchronous characterization of the surface and interface mechanical properties of a thin-film/substrate system is further studied theoretically. The large deflection problem of the steady shaft-loaded blistering thin film is reformulated by surrendering the small-rotation-angle assumption of the membrane, which was previously adopted in the out-of-plane and in-plane equilibrium and radial geometric equations. A new and more accurate analytical solution to this large deflection problem is presented and is used to improve the previously presented synchronous characterization theory. The new analytical solution is numerically compared with the previous analytical solution to confirm the superiority of the new analytical solution over the previous analytical solution. An experiment is conducted to verify the beneficial effect of the improved synchronous characterization theory on improving the characterization accuracy. Full article