Search Results (374)

The development of sensitive, low–cost, and visually readable dosimeters for low gamma–ray exposures is important for occupational and environmental radiation monitoring and for other low–dose applications. This work investigates a colorimetric and optical thin–film dosimeter based on polyvinyl alcohol (PVA) containing silver nitrate (AgNO₃) and hafnium oxide (HfO₂). The film was fabricated using a solution–casting technique. The dosimetric response was evaluated over an absorbed–dose range of 22.2–65.2 mGy using diffuse reflectance spectroscopy, Kubelka–Munk (K/S) analysis, CIELAB colorimetry, CMYK image–based analysis, and X–ray diffraction (XRD). Irradiation produced a dose–dependent decrease in visible reflectance and a corresponding increase in optical absorption. The K/S response increased with dose, while CIELAB analysis showed a systematic decrease in lightness and an increase in total color difference (${\Delta \mathrm{E}}_{ab}^{\ast }$), reaching approximately 25 at 65.2 mGy. Linear regression of ${\Delta \mathrm{E}}_{ab}^{\ast }$ over 0–65.2 mGy gave y = 0.399x − 1.0029 with R² = 0.9845. CMYK analysis also showed a clear dose response, with the yellow channel (ΔY) exhibiting the largest relative change among the chromatic channels. XRD identified monoclinic HfO₂ as the dominant crystalline filler phase and showed dose–associated changes in peak intensity, peak position, and the relative prominence of the broad PVA–related feature. At the highest XRD dose, several HfO₂ reflections weakened while the broad contribution near 2θ ≈ 19.9–20° became more prominent. These changes are interpreted as dose–dependent structural modification and partial loss of resolved crystalline order rather than definitive evidence of a newly formed crystalline phase. A surface morphology and microstructure analysis was performed on control and γ–ray–irradiated PVA/HfO₂/AgNO₃ nanocomposite films using scanning electron microscopy (SEM–EDX). The morphological transition to fibrous, tree trunk–like structures seen by SEM is well correlated with the dose–dependent change in composition to higher surface Ag content, supporting the idea that radiation–induced Ag nanoparticle nucleation and growth is the primary degradation mechanism in the irradiated films. The combined optical and colorimetric results demonstrate a measurable response of the PVA/HfO₂/AgNO₃ formulation in the investigated low–mGy gamma–ray range. Full article

Biofilm accumulation on orthodontic appliances is a recognized risk factor for white spot lesion formation and caries during treatment. Antibacterial surface modifications and coating strategies have been proposed as appliance-level preventive approaches. Studied interventions in the literature span true thin-film surface coatings, plasma-based and ion-implantation surface modifications, and bulk-incorporated antibacterial agents in appliance matrix materials. Yet the extent to which in vitro efficacy translates to clinically meaningful protection remains unresolved. This PRISMA-ScR-compliant scoping review searched PubMed/MEDLINE, Scopus, Web of Science, Cochrane Library, and Google Scholar, identifying 109 eligible studies: 96 in vitro, 8 in vivo animal studies and 5 clinical trials, covering brackets, archwires, clear aligners, bands, miniscrews, elastomeric ligatures, and removable appliances, some articles studied multiple types of appliances. In vitro studies consistently demonstrated significant reductions in bacterial adhesion and biofilm formation across all appliance types, with silver-based coatings and nitrogen-doped TiO₂ showing the broadest evidence base; combination systems (Ag/ZnO, CuO-ZnO) outperformed individual agents. The 13 in vivo and clinical studies provided limited but directionally supportive evidence: silver nanoparticle-incorporated acrylic retainers reduced S. mutans counts in a double-blind RCT, and silver-infiltrated tungsten material-maintained biofilm reduction after simulated two-year abrasion. Coating durability emerged as an important determinant of potential clinical translation. Surface-deposited thin-film coatings degraded substantially within one month of intraoral use, whereas substrate-integrated approaches showed greater longevity. This scoping review maps the current evidence landscape, identifies coating durability and clinical endpoint validation as critical gaps, and prioritizes silver-based and nitrogen-doped TiO₂ coatings for future randomized clinical trials. Full article

Flexible pressure sensors serve as core sensing components for wearable health monitoring systems, electronic skins for soft robots, and flexible human–machine interaction devices. Benefiting from the interfacial electric double-layer polarization effect, iontronic sensing delivers far higher pressure response sensitivity than conventional parallel-plate capacitive sensors, endowing it with distinctive advantages in the detection of weak physiological signals. Nevertheless, current dense ionic thin-film dielectric layers suffer from limited deformation space under compression and poor low-pressure sensing capability. Mainstream high-precision micropillar arrays are fabricated via photolithography, 3D printing, and metal etching molds, which require costly equipment and complicated fabrication procedures, making large-area mass production unfeasible. Random frosted concave-convex microstructures feature disordered dimensions, leading to severe device hysteresis and narrow linear ranges, which fail to achieve ultrahigh sensitivity alongside a wide pressure detection range simultaneously. To address the aforementioned multiple bottlenecks, this paper proposes a low-cost resin template replication process to fabricate TPU-based ionic thin-film dielectric layers with ordered micropillar array microstructures. Combined with inkjet-printed silver conductive PI flexible electrodes, an iontronic flexible pressure sensor with a sandwich layered structure is constructed. Multi-dimensional investigations including microscopic morphology characterization, electromechanical sensing performance calibration, and human wearable application tests are systematically implemented to thoroughly elucidate the synergistic enhancement mechanism of the arrayed micropillars. Test results demonstrate that the effective pressure detection range of the sensor spans 0–1038 kPa, accommodating ultra-low pressures such as pulse signals as well as medium-to-high-pressure loads including joint bending. The sensitivity reaches 23.27 kPa⁻¹ within the low-pressure range of 0–200 kPa and remains stable at 3.52 kPa⁻¹ in the high-pressure range of 200–1038 kPa, with piecewise linear fitting correlation coefficients of 0.93 and 0.96 respectively. Both the response time and recovery time of the device are 40 ms, and the hysteresis error throughout the loading-unloading cycle is merely 2.62%. After 20,000 consecutive cyclic loading-unloading tests, the peak capacitance output only decays by 5.1%, verifying outstanding mechanical fatigue resistance and electrical stability. Validations in multi-scenario applications prove that the sensor can accurately capture human physiological and motion signals including radial artery pulses, laryngeal deformation induced by multi-syllable vocalization, and multi-angle bending of fingers and elbow joints, suitable for home-based health monitoring, quantitative rehabilitation training, flexible tactile interaction and other scenarios. The entire fabrication process eliminates high-precision micro-nano processing equipment such as photolithography systems, plasma etchers and 3D printers; only general chemical raw materials and conventional laboratory instruments are adopted. The reusable templates enable low manufacturing costs and large-area coating forming, offering a novel low-cost technical solution for the engineering implementation and industrialization of high-performance iontronic flexible pressure sensors. Full article

Silver (Ag)-based conductive coatings are widely used in electrical contacts due to their excellent electrical conductivity, low contact resistance, good thermal stability and oxidation resistance, although their susceptibility to sulfidation and environmental corrosion is a concern under certain service conditions. In recent years, significant progress has been achieved in both the manufacture and performance optimization of Ag-based coatings to satisfy the demanding requirements of modern electrical and electronic systems. This review summarizes recent advances in fabrication techniques and processing parameters for Ag-based coatings, including electroplating, electroless deposition, magnetron sputtering, electrospark deposition, thermal spraying, and electrical explosion spraying on metallic substrates, particularly on copper and steel substrates. More attention is given to microstructural design strategies, such as the incorporation and homogeneous dispersion of reinforcement or solid lubricant phases within the Ag matrix, to enhance contact reliability and operational endurance. The performance of Ag-based coatings is analyzed in terms of their physical, chemical and mechanical properties, electrical contact resistance, friction and wear behavior, arc erosion resistance, and environmental durability under different service conditions. Key challenges, including coating degradation under high electrical loads, mechanical wear, and corrosive environments, are highlighted. Future research directions are outlined, focusing on multifunctional coating structures that enhance surface performance and ensure the long-term durability of electrical contacts. Full article

Low-emissivity (low-E) coatings are among the most effective thin-film technologies for reducing radiative heat losses and controlling solar heat gain in buildings, which account for approximately 30–40% of global primary energy consumption. This expanded review follows the technological evolution of low-E glazing from early transparent-conductor “heat mirrors” to modern multi-silver dielectric/metal/dielectric (D/M/D) architectures and emerging functional coatings. Four complementary perspectives are addressed: (i) the materials employed, from silver-based multilayers and transparent conducting oxides (ITO, FTO, AZO, GZO) to seed, blocker, and protective dielectric layers; (ii) the deposition systems, contrasting on-line pyrolytic/CVD “hard” coatings with off-line magnetron-sputtered “soft” coatings, together with ALD, sol–gel, and evaporation routes; (iii) the methods of analysis used to correlate microstructure, composition. and interfaces with optical, electrical, and thermal behaviour (XRD, XRR, SEM/TEM, AFM, XPS, SIMS, spectrophotometry, ellipsometry, emissivity, and U-value metrology according to EN 410/EN 673 and ISO 9050); and (iv) the functional performance of low-E stacks in insulating glass units, vacuum glazing, retrofit films, and smart-window systems across climate zones. Persistent research gaps are identified in long-term durability and ageing, indium-free scalable materials, standardized accelerated testing, and multi-objective design of thinner, more selective, and more robust stacks. Full article

The performance of low-temperature detectors utilizing thermal effects is determined by their energy relaxation properties. Usually, heat transport experiments in mesoscopic structures are carried out in the steady state, where temperature gradients do not change in time. Here, we present an experimental study of dynamic thermal relaxation in a mesoscopic system—thin metallic film. We find that thermal relaxation of hot electrons in copper and silver films is characterized by several time constants, and that the annealing of the films changes them. In most cases, two time constants are observed, and we can model the system by introducing an additional thermal reservoir coupled to the film electrons. We determine the specific heat of this reservoir and its coupling to the electrons. We suspect that multiscale thermal relaxation arises from the complicated morphology of the films, in which the electron–phonon coupling strength in grains with different orientations varies. Full article

The formation and stabilization of silver nanoparticles (AgNPs) in thin films of ionic liquids (ILs) based on long-chain alkylimidazolium cations are demonstrated in this work. IL films were prepared by vacuum thermal evaporation using the Knudsen effusion method onto ITO/glass substrates, leading to the formation of micro- and nanosized structures distributed across the surface. The investigated ILs were symmetrical dialkylimidazolium-based systems: [C₇C₇im][NTf₂], [C₈C₈im][NTf₂], and [C₁₀C₁₀im][NTf₂]. Increasing the alkyl side-chain length of the imidazolium cation resulted in larger droplet domains. AgNPs were subsequently deposited onto the IL films by sputtering. The formation of AgNPs was confirmed by scanning electron microscopy (SEM), ultraviolet (UV)–visible spectroscopy, and X-ray photoelectron spectroscopy (XPS). The results show that increasing the alkyl side-chain length promotes more effective confinement and stabilization of AgNPs, leading to improved nanoparticle formation and a narrower size distribution. The temporal stability of the Ag-containing IL films was evaluated under both air exposure and inert argon storage, revealing a strong influence of the surrounding atmosphere on nanoparticle evolution. Among the ILs studied, [C₁₀C₁₀im][NTf₂] exhibited the most favorable behavior for AgNP formation and stabilization, providing a more stable and homogeneous nanoparticle distribution over time. Full article

The thermal contact resistance between a clip-attached TO 247 package and heat sink is a very large contributor to the total thermal resistance. Therefore, it is important to investigate its reliability and lifetime behavior. The novelty of this investigation is the new, detailed lifetime behavior measurement results of thermal contact resistance between package and heat sink. We have carried out an accelerated lifetime test on 30 samples at 110 °C with acceleration factor of 35 for 18 weeks, corresponding to 12.1 years operating life in indoor environments. The samples were 7 without interlayer film, 12 with 12.5 µm thick silver film and 11 with 6 µm thick silver film. At the start of the test, the average of the thermal contact resistance of samples with 12.5 µm silver film was 20.7% lower, and with 6 µm silver film, the average of thermal contact resistance was 8.7% lower than the average of thermal contact resistance of samples without film. During the first operating month, thermal contact resistance decreased by an average of 5%. Then followed an additional 5% decrease for 12 years. All individual samples show lower thermal contact resistance after 12.1 years compared to the start. No failures were observed, not even among high outliers. By a visual inspection of heat sink surfaces, high outliers can be avoided from start. The thermal contact resistance variation is smaller for samples with silver films compared to samples without film. Samples show decreasing thermal contact resistance with increasing dissipated power. Several previously known stabilizing mechanisms can hypothetically explain the results. Not only the softness of silver, but also the high ductility and Poisson Ratio, which elongate a 12.5 µm thick film more than a 6 µm thick µm film, are hypothesized to better fill out microscopic voids. We observe silver film surface structure changes when comparing aged silver films to un-aged silver films, indicating material movements, but no exact mechanism could be proven. Therefore, the explanations studied are hypothetical. Since all measured thermal contact resistances were lower after 12.1 years, our conclusion is that stabilizing types of mechanisms are dominant during the operating lifetime for indoor environments. Full article

A capillary-driven microfluidic electrical screening platform was developed using silver nanoparticle (AgNP)-decorated laser-patterned villous microstructures on a glass substrate for the analysis of H3N2-infected A549 cells. The device integrated nanosecond laser patterning, AgNP conductive thin-film formation, passive capillary transport, and direct electrical readout within a single microfluidic sensing structure. Villous-like arrays were fabricated using a 1064 nm IR pulsed laser at a fluence of 4.35 J/cm², with a repetition rate of 300 kHz, pulse overlap of 96.7% and scanning speed of 500 mm/s. The fabricated structures exhibited a diameter of 60 μm, height of 80 μm and interpillar pitches ranging from 30 to 90 μm. After AgNP deposition, the surface showed a dominant Ag content of 59.2%, confirming successful formation of conductive microstructured electrodes. The 30 μm pitch structure produced the highest current response of 22 μA at 1 V and the highest ΔI_norm of 0.053 after introduction of H3N2-infected A549 samples. Wettability and capillary transport were tunable by pitch, with contact angles (CAs) decreasing from 140° to 30° and flow velocities decreasing from 0.1 mm/s to 0.03 mm/s. Formalin-fixed H3N2-infected A549 cells were electrically distinguished from non-infected A549 controls over 10¹–10⁶ PFU/μL, with detectable responses down to 10¹ PFU/μL. These results demonstrate a label-free, self-driven, and fabrication-oriented microfluidic strategy for electrical screening of virus-associated cellular samples. Full article

Although optical fiber-based surface plasmon resonance (SPR) sensors have revolutionized real-time, label-free biosensing, conventional designs suffer from limited multi-analyte detection capabilities. This study utilizes the novel Pi (π)-configured dual SPR optical fiber sensor with two opposing side-polished surfaces, enabling plasmonic excitation for simultaneous multi-analyte detection. The proposed sensor leverages asymmetric metallic thin films such as Ag, Au, Cu, and hybrid configurations (metal + TiO₂) to generate two distinct resonance peaks, significantly enhancing detection versatility. Numerical simulations using the finite element method in COMSOL Multiphysics v6.3 demonstrate that the π-configuration achieves dual resonance dips at 982 nm and 1276 nm for Ag and Ag–TiO₂ films, 1040 nm and 1317 nm for Au and Au–TiO₂ films, and 977 nm and 1249 nm for Cu and Cu–TiO₂ films, respectively, for an analyte refractive index of 1.42. A peak spectral separation >125 nm was achieved for all the sensors for a refractive index range of 1.37–1.42, ensuring that the two dips are resolvable since the change in SPR wavelength is greater than or equal to the full width at half maximum, preserving dual-analyte capability and minimizing potential crosstalk. The results indicate that the π-configured dual SPR sensor utilizing silver and silver–TiO₂ sensing layers had the highest wavelength sensitivity of 12,600 nmRIU⁻¹ and 20,000 nmRIU⁻¹, respectively, slightly outperforming its gold and copper counterpart. The optimized metallic and hybrid nanostructured films ensure dual distinct peaks with high sensitivity, while maximizing refractive index resolution. This work presents the design of a π-configured SPR-based optical fiber sensor utilizing dielectric and multi-metallic thin films, thereby offering a breakthrough in multiplexed biosensing for applications in medical diagnostics, environmental monitoring, and chemical detection. Full article

Background: Increasing antifungal resistance, poor mucosal retention, and systemic side effects limit the effectiveness of currently available drugs. This study explores a novel topical nanotherapeutic approach for the targeted treatment of vulvovaginal candidiasis (VVC), employing green-synthesized silver nanoparticles (AgNPs) derived from Ascophyllum nodosum (AN) and incorporating ibrexafungerp citrate (IBC) into a liposomal formulation. Methods: AgNPs were biosynthesized using AN extract and characterized. Liposomes were prepared by thin-film hydration, and optimised using Central Composite design and characterized and optimized. Optimised liposomes, co-loaded with IBC and AN-AgNPs, were incorporated into a Carbopol-CMC-based topical gel. Results: FTIR shifts in the –OH (3332.31 cm⁻¹) and carbonyl (1636.87 cm⁻¹) bands with reduced intensity confirmed their involvement in Ag⁺ reduction and nanoparticle surface coordination, while the persistence of the 1015 cm⁻¹ band indicated the role of polysaccharides in capping and stabilizing the AN-AgNP. Characterization of the optimized liposomes (IBCL-11) revealed a particle size of 127.2 nm, a zeta potential of −43.8 mV, and a polydispersity index (PDI) of 0.35. Transmission Electron Microscopy (TEM) confirmed the presence of intact, spherical vesicles, while Differential Scanning Calorimetry (DSC) and X-ray diffraction (XRD) validated the molecular dispersion and amorphous characteristics of the films. In vitro evaluations of the IBC liposomal gel demonstrated a sustained drug release of 72.6% over 24 h, alongside enhanced drug penetration across all skin layers. Antifungal assays highlighted the formulation’s potent efficacy, yielding Minimum Inhibitory Concentration (MIC) and Minimum Fungicidal Concentration (MFC) values below 1 µg/mL. Furthermore, the treatments exhibited strong anti-biofilm properties; at MIC and MBC levels, AN-AgNPs achieved biofilm reductions of 45.27 ± 3.16% and 27.62 ± 2.13%, respectively, whereas IBCL-11 produced reductions of 34.25 ± 2.43% and 16.28 ± 1.72%. Conclusion: Ultimately, this study successfully developed an eco-friendly liposomal formulation co-loaded with AN-AgNPs and IBC, offering a promising and targeted therapeutic approach for the treatment of vulvovaginal candidiasis. Full article

High-temperature sintered conductive silver paste serves as a critical material in the fabrication of electronic components, with its performance directly influencing device reliability and integration density. In this work, conductive silver paste was prepared via a ball milling method by dispersing silver powder (conductive filler), glass powder (binder), and ethyl cellulose (EC, thickener) in an organic carrier composed of α-terpineol, diethylene glycol butyl ether acetate (DBA), and dimethyl phthalate (DMP) at specific ratios. The effects of the formulation composition and preparation process on the rheological properties of the paste as well as the electrical and mechanical properties of the resulting films were systematically investigated. The results indicated that sintering time and temperature exerted regular effects on the resistance of the silver paste; ball milling speed and duration influenced the particle size distribution, thereby affecting the resistance behavior; thixotropy significantly impacted the resistance characteristics. Under optimal conditions, where the organic carrier consisted of α-terpineol, DBA, and DMP at a ratio of 6:3:1, with 30 wt.% silver powder, 18 wt.% glass powder, and 4 wt.% EC, combined with a sintering temperature of 500 °C for 50–60 min, a ball milling speed of 500–600 r/min, and a ball milling time of approximately 1.5 h, the obtained silver paste exhibited pronounced shear-thinning behavior and excellent thixotropy, indicating favorable processability. The corresponding silver paste film demonstrated the lowest resistivity, superior bending resistance, and good adhesion to both PET and glass substrates. This study provides valuable insights for the design and preparation of high-performance, high-temperature sintered conductive silver pastes. Full article

This review summarizes the base materials, joining methods, filler materials, and principal technical challenges in endoscope joining fabrication, and proposes practical strategies to improve joint reliability under clinical constraints. We conducted a comprehensive search in multiple databases, including Web of Science, Google Scholar, patent databases, Scopus databases, and Medline (via PubMed), for articles on the joining for precision endoscope fabrication, covering the period from 1950 to 2026. We employed the combinations of keywords, “endoscopy”, “minimally invasive surgery”, “welding”, “joining”, “sealing”, “soldering”, “bonding”, and “brazing”. Approximately 500 references were retrieved. After excluding duplicates and irrelevant studies, 158 publications met the inclusion criteria. Data on base materials, joining, processes, filler materials, and technical issues related to sterilization, corrosion, and microstructural evolution were extracted and analyzed. Endoscopes are multi-material systems, involving metallic biomaterials (stainless steels (SSs), titanium alloys, nickel-based alloys, etc.), optical functional materials (glass, sapphire, quartz, etc.), engineering plastics, ceramics, composite materials, and coatings. Joining, sealing, and functional integration have been achieved via adhesive bonding, laser soldering, laser brazing, wave soldering, reflow soldering, fusion welding, and other joining techniques. The main challenges include how to reliably join highly mismatched dissimilar materials, how to fabricate low-residual-stress joints, and how to increase the long-term resistance to sterilization-induced degradation and thermal aging over repeated 100–200 °C thermal cycles. Conventional joining techniques struggle to balance mechanical integrity, joint hermeticity, and long-term stability under such harsh cyclic conditions. The resulting joints may suffer surface yellowing, interfacial debonding, microcracking, delamination, or progressive property degradation during service. We propose the following three strategies to achieve reliable, low-residual-stress, and sterilization-resistant joining of dissimilar materials for endoscopes: (1) A synergistic design that combines thin-film engineering (including evaporation, sputtering, and electroplating) with silver anti-oxidation layers is proposed to reduce residual stresses and to enhance the joint hermeticity. (2) To develop principles for the selection of multi-joining processes to achieve the multi-material integration and functional assembly of dissimilar material components. (3) To develop the laser-based joining methods (fusion, brazing, or braze-welding) for precision control of heat input, bonding quality, and the least damage to the heat-sensitive components. Full article

Organic-type solar cells containing an active layer of block copolymer donor PTB7-Fx (x = 0, 20, and 100), based on benzo [1,2-b:4,5-b’]dithiophene and variably fluorinated thieno [3,4-b]thiophene units, and fullerene acceptor [6,6]phenyl-C₇₁-methylbutyrate, were constructed. The active layer thin film of the solar cells was obtained from a dichlorobenzene solution at an established concentration via spin-coating of the donor–acceptor mixture in the presence of solvent additives such as 3% diiodooctane and 1% triethyl phosphate. Organic photovoltaic elements with normal device architecture were prepared on glass substrates using an indium tin oxide anode, a spin-coated hole transporting layer of poly(ethylene dioxythiophene):polystyrenesulfonate, the aforementioned active layer, followed by an electron transporting layer of zinc oxide nanoparticles, and finally a magnetron sputtered silver (Ag) top-electrode. The optical properties, thin film morphology, and the thickness of the active layers were investigated. Additionally, current density–voltage characteristics and impedance spectra of photovoltaic devices were measured. It was found that PTB7-Fx:PC₇₁BM-based solar cells processed in the presence of two types of solvent additives, diiodooctane and triethyl phosphate, with a sputtered Ag top-electrode display similar absorption and quantum efficiency spectra, as well as comparable current density–voltage characteristics and efficiencies to the same devices fabricated without additives. The diiodooctane solvent additive preferably dissolves the fullerene component and has a positive effect on fill factor enhancement, impedance spectra improvement, and amelioration in charge carrier transport and collection, whereas the triethyl phosphate solvent additive preferentially dissolves the copolymer donor and has a more pronounced impact on the refined morphology of the thin film active layers. Full article